x/tools/go/analysis/passes/shadow: go vet shadow strict doesn't check global constant shadowing

[gergely-pepper]

Go version

go version go1.24.0 darwin/arm64

Output of go env in your module/workspace:

AR='ar'
CC='clang'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='clang++'
GCCGO='gccgo'
GO111MODULE='auto'
GOARCH='arm64'
GOARM64='v8.0'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/Users/gergely-pepperstone/Library/Caches/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/Users/gergely-pepperstone/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/var/folders/vc/jvx1n9n12bq0_fhbqlb2sv_00000gp/T/go-build1999280843=/tmp/go-build -gno-record-gcc-switches -fno-common'
GOHOSTARCH='arm64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMOD=''
GOMODCACHE='/Users/gergely-pepperstone/og/pkg/mod'
GONOPROXY='github.com/pepperstone'
GONOSUMDB='github.com/pepperstone'
GOOS='darwin'
GOPATH='/Users/gergely-pepperstone/og'
GOPRIVATE='github.com/pepperstone'
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/Users/gergely-pepperstone/Library/Application Support/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/darwin_arm64'
GOVCS=''
GOVERSION='go1.24.0'
GOWORK=''
PKG_CONFIG='pkg-config'

What did you do?

package main

import "fmt"

const testStr = "some"

func main() {
	if testStr != "" {
		fmt.Println("Not empty")
	}
	testStr := "Test string"
	fmt.Println(testStr)
}

go vet -vettool="$(which shadow)" -strict .

What did you see happen?

no output

What did you expect to see?

./vet.go:11:2: declaration of "testStr" shadows declaration at line 5

[gabyhelp]

Related Issues

• x/tools/go/analysis/passes/shadow: "go vet --shadow" doesn't check global variable shadowing #35731 (closed)
• cmd/vet: go vet -vettool=$(which shadow) errors in go1.13 only (flag provided but not defined: -unsafeptr) #34053 (closed)
• cmd/vet: shadow false positive variable/type declaration in package block #18018 (closed)
• x/tools/go/analysis/passes/shadow/cmd/shadow: Failure/success of the linter depends also on filename, not just the content #40758
• cmd/vet: obvious shadowing is not detected #21606 (closed)
• cmd/vet: go 1.18 vet undocumented behavior change with use of -vettool #50195 (closed)
• cmd/go: 'go vet --shadow' not detecting shadowed variable #21638 (closed)
• x/tools/go/analysis/passes/shadow/cmd/shadow: shadow inconsistent failures when var in code shadows a var in a test file #34557 (closed)
• go vet #46946 (closed)

Related Discussions

• Surprising behavior in `go tool vet -shadow`

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[cherrymui]

cc @adonovan

[adonovan]

Since its inception, the shadow analyzer has always had problems that prevent us from enabling it. Until we know how to fix them, we are unlikely to invest more effort into it.