cmd/go: debug.BuildInfo doesn't include VCS info when cross-compiling [1.18rc1]

[spyder-jeff]

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

$ go version
go version go1.18rc1 linux/arm64

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="arm64"
GOBIN=""
GOCACHE="/home/vagrant/.cache/go-build"
GOENV="/home/vagrant/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/vagrant/go/pkg/mod"
GONOPROXY="*"
GONOSUMDB="*"
GOOS="linux"
GOPATH="/home/vagrant/go"
GOPRIVATE="*"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go1.18rc1"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go1.18rc1/pkg/tool/linux_arm64"
GOVCS=""
GOVERSION="go1.18rc1"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/vagrant/spyderbat/aws_terraform/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 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3002789791=/tmp/go-build -gno-record-gcc-switches"

What did you do?

building on arm64 for amd64:

	vcsrevision := "unknown"
	vcsdirty := ""
	vcstime := "unknown"

	if info, ok := debug.ReadBuildInfo(); ok {
		for _, v := range info.Settings {
			switch v.Key {
			case "vcs.revision":
				vcsrevision = v.Value
			case "vcs.modified":
				if v.Value == "true" {
					vcsdirty = " (dirty)"
				}
			case "vcs.time":
				vcstime = v.Value
			}
		}
	}

What did you expect to see?

vcs info, when cross-compiling to AMD64

What did you see instead?

"unknown"

(works when building for native arm64)

[dmitshur]

CC @bcmills, @rsc.

[bcmills]

I don't see anything in the -buildvcs implementation that would vary based on whether you are cross-compiling.
What were the exact commands that you ran for the two builds?

[spyder-jeff]

I'm sorry, I'm dumb. It wasn't cross-compiling that was doing it, it was an artifact of the way the Makefile was written. It turns out that if you do go build foo.go instead of just go build, you don't get vcs info. Maybe that's expected? I hope not.

Sample project: https://github.com/jnoxon/vcspoc

[seankhliao]

Duplicate of #51279