cmd/go: binary does not contain VCS information when compiled in git worktree dir

[rogpeppe]

What version of Go are you using (go version)?

$ go version
go version go1.20rc3 linux/amd64

Does this issue reproduce with the latest release?

Yes.

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE="auto"
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/rogpeppe/.cache/go-build"
GOENV="/home/rogpeppe/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/rogpeppe/src/go/pkg/mod"
GONOPROXY="github.com/influxdata/idpe"
GONOSUMDB="github.com/influxdata/idpe"
GOOS="linux"
GOPATH="/home/rogpeppe/src/go"
GOPRIVATE="github.com/influxdata/idpe"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/rogpeppe/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/rogpeppe/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.20rc3"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/rogpeppe/src/cuelabs/cue2/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 -fdebug-prefix-map=/tmp/go-build3009011258=/tmp/go-build -gno-record-gcc-switches"

What did you do?

Run testscript on the following file:

# set up git repository and build first binary
cd d1
exec git init
exec git add .
exec git commit -m 'initial commit'
exec go build -o $TMPDIR/prog1 .

# set up worktree and build second binary
exec git worktree add -b main1 ../d2 HEAD
cd ../d2
exec go build -o $TMPDIR/prog2 .

# ensure first binary has VCS info
exec go version -m $TMPDIR/prog1
stdout 'vcs.revision='

# ensure second binary has VCS info
exec go version -m $TMPDIR/prog2
stdout 'vcs.revision='

-- d1/go.mod --
module example

-- d1/main.go --
package main

func main() {}

What did you expect to see?

A successful test.

What did you see instead?

The binary built in a git worktree directory does not contain VCS information.
I suspect the logic doesn't understand that .git can be a file was well as a directory.

# set up git repository and build first binary (0.096s)
# set up worktree and build second binary (0.088s)
# ensure first binary has VCS info (0.002s)
# ensure second binary has VCS info (0.002s)
> exec go version -m $TMPDIR/prog2
[stdout]
$WORK/.tmp/prog2: go1.20rc3
	path	example
	mod	example	(devel)	
	build	-buildmode=exe
	build	-compiler=gc
	build	CGO_ENABLED=1
	build	CGO_CFLAGS=
	build	CGO_CPPFLAGS=
	build	CGO_CXXFLAGS=
	build	CGO_LDFLAGS=
	build	GOARCH=amd64
	build	GOOS=linux
	build	GOAMD64=v1
> stdout 'vcs.revision='
FAIL: /tmp/testscript498691614/x.txtar/script.txtar:19: no match for `vcs.revision=` found in stdout
error running /tmp/x.txtar in /tmp/testscript498691614/x.txtar

[mknyszek]

CC @bcmills @matloob

[mknyszek]

Does this reproduce with earlier releases?

[mvdan]

It does; I have a fix ready. It's a rather simple one, we were just assuming that .git was always a directory in -buildvcs=auto.

[gopherbot]

Change https://go.dev/cl/463849 mentions this issue: cmd/go: support git worktree checkouts in -buildvcs=auto

[tie]

As mentioned in #58978 and #59068, this issue also affects work trees inside bare Git repositories where running git status --porcelain fails since it must be run in a work tree. That is, go build with VCS stamping (including auto mode) fails in such setup.

1. Go looks for .git, which is currently only allowed to be a directory.
2. Finds .git directory from the bare repository (see also git config core.bare).
3. Runs git status there, outside of the work tree.