Go 1.18 - failed to process with func assignment

[matheusoliveira]

Welcome

• Yes, I'm using a binary release within 2 latest major releases. Only such installations are supported.
• Yes, I've searched similar issues on GitHub and didn't find any.
• Yes, I've included all information below (version, config, etc).
• Yes, I've tried with the standalone linter if available. (https://golangci-lint.run/usage/linters/)

Description of the problem

Hi all,

I believe I found an issue with Go 1.18 and generics, and I couldn't find this specific one at #2649, so I'm opening this issue. Sorry if it is the wrong approach.

The problem appears when I try to set a func variable from a generic version (e.g. func MyFunc[T any]() T) into a variable (e.g. var x func() string = MyFunc[string]), and golangci-lint fails.

From what I understand it is failing to even compile the project, so it is not even doing that in an specific lint, but I'm not sure of that.

You can find details with a minimalist sample code bellow.

Version of golangci-lint

$ golangci-lint --version
golangci-lint has version v1.46.2 built from a3336890 on 2022-05-17T11:51:30Z

Configuration file

No config file used.

Go environment

$ go version
go version go1.18.3 linux/amd64

Verbose output of running

$ docker run --rm -v $(pwd):/app -w /app golangci/golangci-lint:v1.46.2 golangci-lint run -v
level=info msg="[config_reader] Config search paths: [./ /app / /root]"
level=info msg="[lintersdb] Active 10 linters: [deadcode errcheck gosimple govet ineffassign staticcheck structcheck typecheck unused varcheck]"
level=info msg="[loader] Go packages loading at mode 575 (types_sizes|compiled_files|files|imports|deps|exports_file|name) took 149.583638ms"
level=info msg="[runner/filename_unadjuster] Pre-built 0 adjustments in 133.082µs"
level=info msg="[linters context/goanalysis] analyzers took 1.268340744s with top 10 stages: buildir: 887.014509ms, inspect: 72.124674ms, fact_purity: 69.883557ms, nilness: 58.739632ms, ctrlflow: 47.670682ms, fact_deprecated: 46.621729ms, printf: 35.930006ms, SA5012: 31.399724ms, typedness: 16.470586ms, S1030: 116.195µs"
level=error msg="[runner] Panic: buildir: package \"main\" (isInitialPkg: true, needAnalyzeSource: true): in lint-test.main: cannot convert lint-test.Foo (func[T any]() T) to func() string: goroutine 1160 [running]:\nruntime/debug.Stack()\n\truntime/debug/stack.go:24 +0x65\ngithub.com/golangci/golangci-lint/pkg/golinters/goanalysis.(*action).analyzeSafe.func1()\n\tgithub.com/golangci/golangci-lint/pkg/golinters/goanalysis/runner_action.go:101 +0x155\npanic({0xea9680, 0xc00eb10f40})\n\truntime/panic.go:838 +0x207\nhonnef.co/go/tools/go/ir.emitConv(0xc001284000, {0x1270190, 0xc001281e00}, {0x12662a8?, 0xc003a38980}, {0x1265650, 0xc003a38480})\n\thonnef.co/go/tools@v0.3.1/go/ir/emit.go:293 +0xd29\nhonnef.co/go/tools/go/ir.emitStore(0xc001284000, {0x126fc48, 0xc001d21800}, {0x1270190, 0xc001281e00}, {0x1265650, 0xc003a38480})\n\thonnef.co/go/tools@v0.3.1/go/ir/emit.go:302 +0x7f\nhonnef.co/go/tools/go/ir.(*address).store(0xc0051826c0, 0x0?, {0x1270190?, 0xc001281e00?}, {0x1265650?, 0xc003a38480?})\n\thonnef.co/go/tools@v0.3.1/go/ir/lvalue.go:37 +0x53\nhonnef.co/go/tools/go/ir.(*storebuf).emit(0x1265650?, 0xc001284000)\n\thonnef.co/go/tools@v0.3.1/go/ir/builder.go:455 +0xeb\nhonnef.co/go/tools/go/ir.(*builder).assignStmt(0xc00d0b84b0?, 0xc001284000, {0xc001c921c0, 0x1, 0x0?}, {0xc001c921d0, 0x1, 0x0?}, 0x0, {0x1265650, ...})\n\thonnef.co/go/tools@v0.3.1/go/ir/builder.go:1113 +0x2de\nhonnef.co/go/tools/go/ir.(*builder).stmt(0x0?, 0xc001284000, {0x1268c20?, 0xc003a38480?})\n\thonnef.co/go/tools@v0.3.1/go/ir/builder.go:2245 +0xa0b\nhonnef.co/go/tools/go/ir.(*builder).stmtList(0x0?, 0x0?, {0xc003a38600?, 0x4, 0x0?})\n\thonnef.co/go/tools@v0.3.1/go/ir/builder.go:848 +0x67\nhonnef.co/go/tools/go/ir.(*builder).stmt(0xc001284000?, 0xc001284000, {0x1268d40?, 0xc0031d44b0?})\n\thonnef.co/go/tools@v0.3.1/go/ir/builder.go:2331 +0xd31\nhonnef.co/go/tools/go/ir.(*builder).buildFunction(0xc000adfa28, 0xc001284000)\n\thonnef.co/go/tools@v0.3.1/go/ir/builder.go:2443 +0x453\nhonnef.co/go/tools/go/ir.(*builder).buildFuncDecl(0xc00175a380?, 0xc00018da70, 0xc0031d4510)\n\thonnef.co/go/tools@v0.3.1/go/ir/builder.go:2481 +0x195\nhonnef.co/go/tools/go/ir.(*Package).build(0xc00018da70)\n\thonnef.co/go/tools@v0.3.1/go/ir/builder.go:2587 +0xc52\nsync.(*Once).doSlow(0xc00175a000?, 0xc00d0b8960?)\n\tsync/once.go:68 +0xc2\nsync.(*Once).Do(...)\n\tsync/once.go:59\nhonnef.co/go/tools/go/ir.(*Package).Build(...)\n\thonnef.co/go/tools@v0.3.1/go/ir/builder.go:2505\nhonnef.co/go/tools/internal/passes/buildir.run(0xc0000b8000)\n\thonnef.co/go/tools@v0.3.1/internal/passes/buildir/buildir.go:86 +0x368\ngithub.com/golangci/golangci-lint/pkg/golinters/goanalysis.(*action).analyze(0xc000725050)\n\tgithub.com/golangci/golangci-lint/pkg/golinters/goanalysis/runner_action.go:187 +0x9c4\ngithub.com/golangci/golangci-lint/pkg/golinters/goanalysis.(*action).analyzeSafe.func2()\n\tgithub.com/golangci/golangci-lint/pkg/golinters/goanalysis/runner_action.go:105 +0x1d\ngithub.com/golangci/golangci-lint/pkg/timeutils.(*Stopwatch).TrackStage(0xc00035c3c0, {0x101a559, 0x7}, 0xc000620748)\n\tgithub.com/golangci/golangci-lint/pkg/timeutils/stopwatch.go:111 +0x4a\ngithub.com/golangci/golangci-lint/pkg/golinters/goanalysis.(*action).analyzeSafe(0xc001090360?)\n\tgithub.com/golangci/golangci-lint/pkg/golinters/goanalysis/runner_action.go:104 +0x85\ngithub.com/golangci/golangci-lint/pkg/golinters/goanalysis.(*loadingPackage).analyze.func2(0xc000725050)\n\tgithub.com/golangci/golangci-lint/pkg/golinters/goanalysis/runner_loadingpackage.go:80 +0xb4\ncreated by github.com/golangci/golangci-lint/pkg/golinters/goanalysis.(*loadingPackage).analyze\n\tgithub.com/golangci/golangci-lint/pkg/golinters/goanalysis/runner_loadingpackage.go:75 +0x1eb\n"
level=warning msg="[runner] Can't run linter goanalysis_metalinter: goanalysis_metalinter: buildir: package \"main\" (isInitialPkg: true, needAnalyzeSource: true): in lint-test.main: cannot convert lint-test.Foo (func[T any]() T) to func() string"
level=warning msg="[linters context] structcheck is disabled because of go1.18. You can track the evolution of the go1.18 support by following the https://github.com/golangci/golangci-lint/issues/2649."
level=info msg="[runner] processing took 2.388µs with stages: max_same_issues: 385ns, skip_dirs: 332ns, nolint: 280ns, max_from_linter: 181ns, path_prettifier: 162ns, cgo: 120ns, uniq_by_line: 111ns, exclude: 110ns, autogenerated_exclude: 107ns, skip_files: 107ns, filename_unadjuster: 106ns, exclude-rules: 47ns, path_shortener: 45ns, source_code: 44ns, diff: 43ns, path_prefixer: 43ns, max_per_file_from_linter: 42ns, sort_results: 41ns, severity-rules: 41ns, identifier_marker: 41ns"
level=info msg="[runner] linters took 1.076383933s with stages: goanalysis_metalinter: 1.076346034s, structcheck: 5.957µs"
level=error msg="Running error: 1 error occurred:\n\t* can't run linter goanalysis_metalinter: goanalysis_metalinter: buildir: package \"main\" (isInitialPkg: true, needAnalyzeSource: true): in lint-test.main: cannot convert lint-test.Foo (func[T any]() T) to func() string\n\n"
level=info msg="Memory: 14 samples, avg is 154.0MB, max is 258.8MB"
level=info msg="Execution took 1.233650493s"

Code example or link to a public repository

Sample code (just called it main.go into a project named lint-test):

package main

import (
	"fmt"
)

func Foo[T any]() T {
	var ret T
	return ret
}

func main() {
	var strCaller func() string
	strCaller = Foo[string]
	strCaller()
	fmt.Println("OK")
}

[boring-cyborg]

Hey, thank you for opening your first Issue ! 🙂 If you would like to contribute we have a guide for contributors.

[ldez]

duplicate of #2859

[matheusoliveira]

Indeed it is... Thank you @ldez , and sorry for the duplicate, I tried to find a similar one but failed to do so 😞 .