cmd/go: local version stamping doesn't work with v2+

[MrBoombastic]

Go version

go version go1.24.1 windows/amd64

Output of go env in your module/workspace:

set AR=ar
set CC=gcc
set CGO_CFLAGS=-O2 -g
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-O2 -g
set CGO_ENABLED=0
set CGO_FFLAGS=-O2 -g
set CGO_LDFLAGS=-O2 -g
set CXX=g++
set GCCGO=gccgo
set GO111MODULE=on
set GOAMD64=v1
set GOARCH=amd64
set GOAUTH=netrc
set GOBIN=
set GOCACHE=C:\Users\user\AppData\Local\go-build
set GOCACHEPROG=
set GODEBUG=
set GOENV=C:\Users\user\AppData\Roaming\go\env
set GOEXE=.exe
set GOEXPERIMENT=
set GOFIPS140=off
set GOFLAGS=
set GOGCCFLAGS=-m64 -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=C:\Users\user\AppData\Local\Temp\go-build3582125240=/tmp/go-build -gno-record-gcc-switches
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GOMOD=C:\Users\user\Desktop\path\TestDevel\go.mod
set GOMODCACHE=C:\Users\user\go\pkg\mod
set GONOPROXY=github.com
set GONOSUMDB=github.com
set GOOS=windows
set GOPATH=C:\Users\user\go
set GOPRIVATE=github.com
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=C:/Users/user/go/go1.24.1
set GOSUMDB=sum.golang.org
set GOTELEMETRY=local
set GOTELEMETRYDIR=C:\Users\user\AppData\Roaming\go\telemetry
set GOTMPDIR=
set GOTOOLCHAIN=auto
set GOTOOLDIR=C:\Users\user\go\go1.24.1\pkg\tool\windows_amd64
set GOVCS=
set GOVERSION=go1.24.1
set GOWORK=
set PKG_CONFIG=pkg-config

What did you do?

ReadBuildInfo.Main.Version shows "(devel)" after tagging v2 package as v2.

package main

import (
	"fmt"
	"runtime/debug"
)

func main() {
	info, _ := debug.ReadBuildInfo()
	fmt.Println(info.Main)
}

Although my personal case may be different - I'm not 100% sure how I broke this feature in my private repo - the scenario below successfully reproduces the same output, so I think it's still worth reporting.

Thanks to user truck.dad from the Discord Gophers server for his initial support and the Unix PoC!

What did you see happen?

@echo off

git init
go mod edit -module test.module
git add . && git commit -m "test"
git tag v1.2.3
go build .
test.module.exe

del test.module.exe
go mod edit -module test.module/v2
git add . && git commit -m "test"
git tag v2.3.4
go build .
test.module.exe

Initialized empty Git repository in C:/Users/usr/path/TestDevel/.git/
warning: in the working copy of 'go.mod', LF will be replaced by CRLF the next time Git touches it
warning: in the working copy of 'main.go', LF will be replaced by CRLF the next time Git touches it
[master (root-commit) 950c98b] test
 7 files changed, 57 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 TestDevel.iml
 create mode 100644 go.mod
 create mode 100644 main.go
 create mode 100644 test.bat
 create mode 100644 test.module.exe
 create mode 100644 test.sh

{test.module v1.2.3  <nil>}

warning: in the working copy of 'go.mod', LF will be replaced by CRLF the next time Git touches it
[master 64f3139] test
 2 files changed, 1 insertion(+), 1 deletion(-)
 delete mode 100644 test.module.exe

{test.module/v2 (devel)  <nil>}

What did you expect to see?

{test.module v1.2.3  <nil>}

{test.module/v2 v2.3.4  <nil>}

or pseudoversion, or literally anything other than "(devel)"

[gabyhelp]

Related Issues

• runtime/debug: document BuildInfo.Main.Version == "(devel)" #29228
• runtime/debug: BuildInfo does not honour replace directives #37392 (closed)
• runtime/debug: ReadBuildInfo returns no information about main module #51918 (closed)
• runtime/debug: vcs.modified populated in ReadBuildInfo for go install but not go build #51637 (closed)
• `runtime/debug.BuildInfo.Path`: redundant with `runtime/debug.BuildInfo.Main.Path` #68177 (closed)
• cmd/go: stamped (pseudo) version on build does not work for module in subdirectory #71738
• cmd/go: "go bug" in build on different branch reports version different than "go version" #43981 (closed)
• affected/package: #56389 (closed)
• go.mod versions seem to require tags beginning with "v" to properly resolve. #34512 (closed)
• cmd/go: specifying module branch writes incorrect version tag to go.mod #31287 (closed)

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

[dr2chase]

@golang/compiler @matloob

[rfjakob]

gocryptfs author here. Same thing on Linux @samthanawalla :

~/code/gocryptfs$ git describe
v2.5.2

~/code/gocryptfs$ go build

~/code/gocryptfs$ go version -m gocryptfs | head
gocryptfs: go1.24.1
	path	github.com/rfjakob/gocryptfs/v2
	mod	github.com/rfjakob/gocryptfs/v2	(devel)	

[bdunlap-synack]

i'm seeing the old (devel) behavior even on non 2+ using the 1.24 toolchain / mod version (version of code was 1.2.4). I expected to see the new marked +dirty behavior at worst as documented in the release notes instead. (the repo was clean so it should just work.)

[ldemailly]

@bdunlap-synack details ? repro how?

[gopherbot]

Change https://go.dev/cl/661875 mentions this issue: cmd/go: fix version stamping for v2 modules