go build does not reject unreachable code after return keyword #72837
Description
Go version
1.23.2
Output of go env in your module/workspace:
GO111MODULE='on'
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/chrb/.cache/go-build'
GOENV='/home/chrb/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/chrb/go/pkg/mod'
GONOPROXY='github.com/SpeechGraphics/*'
GONOSUMDB='github.com/SpeechGraphics/*'
GOOS='linux'
GOPATH='/home/chrb/go'
GOPRIVATE='github.com/SpeechGraphics/*'
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.23.2'
GODEBUG=''
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/chrb/.config/go/telemetry'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/home/chrb/go/src/test/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build175631584=/tmp/go-build -gno-record-gcc-switches'What did you do?
go build accepts the following code without any warning or error:
package main
import (
"log"
)
func f() int {
return 1
return 0
x := 1
log.Printf("%d", x)
return 10
}
func main() {
log.Printf("%d", f())
}
go vet does catch the unreachable code, but imho go build should also reject it.
Even go vet does not catch this unreachable code:
func main() {
if false {
log.Printf("hi")
}
}
What did you see happen?
First example: go build compiled the unreachable code without any warnings or error
Second example: neither go build or go vet complained about the unreachable code
What did you expect to see?
Errors or warnings due to unreachable code.