golang/go

cmd/vet: should check unreachable code after os.Exit() like after panic()

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#74585 opened on Jul 11, 2025

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Description

Go version

go1.24.4

Output of go env in your module/workspace:

AR='ar'
CC='gcc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='g++'
GCCGO='gccgo'
GO111MODULE=''
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/home/apocalypse555/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/home/apocalypse555/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build1252593989=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/dev/null'
GOMODCACHE='/home/apocalypse555/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/apocalypse555/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/lib/go'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/apocalypse555/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/lib/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.24.4'
GOWORK=''
PKG_CONFIG='pkg-config'

What did you do?

I run go vet on this code :

func ok(a int) bool {
	if a < 10 {
		//panic(`with that, it's well detected`)
		os.Exit(1)
		return false
	}
	return true
}

(https://go.dev/play/p/CHtVr0fs-yw)

What did you see happen?

No warning like with panic().

What did you expect to see?

A warning like with panic().

It seems odd that an unreachable code is detected after a panic() but not after an os.Exit().

Related issue

https://github.com/golang/go/issues/53968

Contributor guide

Tech stack
go
Domain
toolingdeveloper experience
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Go programming experienceGo vet tool architectureControl flow analysis basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65
Research direction
Investigate how the vet tool currently detects unreachable code after panic(). Look in the cmd/vet directory for the unreachable code check (likely in a file like unreachable.go or similar). Understand the control flow analysis used. Then extend or create a similar check for os.Exit() calls. The related issue #53968 may provide additional context.