Golang cmd/go: misleading fatal: log message when working in a git repo with no commits

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

$ go version
go version go1.18 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=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/mdevan/.cache/go-build"
GOENV="/home/mdevan/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/mdevan/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/mdevan/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.18"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/tmp/x/go.mod"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build1281482272=/tmp/go-build -gno-record-gcc-switches"

What did you do?

$ cd /tmp                                                                                                                                                                     [19/19]
$ git init x
Initialized empty Git repository in /tmp/x/.git/
$ cd x
$ go mod init x
go: creating new go.mod: module x
$ cat > main.go
// You can edit this code!
// Click here and start typing.
package main

import "fmt"

func main() {
        fmt.Println("Hello, 世界")
}
$ go build -v
# cd /tmp/x; git -c log.showsignature=false show -s --format=%H:%ct
fatal: your current branch 'master' does not have any commits yet
$

What did you expect to see?

A successful build.

What did you see instead?

~~Build itself failed.~~

Edit: The build does succeed even though the "fatal" message is printed.

Comment From: seankhliao

you can't do much with an empty git repo, though I've never noticed as I always have git commit --allow-empty -m "root-commit" set as the first commit (so you can push the empty repo upstream).

cc @bcmills @matloob

Comment From: notfilippo

The fatal log message is printed by the git CLI when executing git -c log.showsignature=false show -s --format=%H:%ct on an empty repository. The command can be replaced with git rev-list -n 1 --all --format=%H:%ct, tweaking a bit the parsing to account for the extra header that is printed.

Will open a changelist soon.

Comment From: gopherbot

Change https://go.dev/cl/399828 mentions this issue: cmd/go: prevent fatal when working in a git repo with no commit

Comment From: kevinburkesegment

I just ran into this... can we try again to merge it?