cmd/dist: tools built with `GOROOT_FINAL` cannot locate it when copied to another location

[g4s8]

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

$ go version
go version go1.21.0 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

$ /usr/lib/go/bin/go env
GO111MODULE=''

GOARCH='amd64'

GOBIN=''

GOCACHE='/home/g4s8/.cache/go-build'

GOENV='/home/g4s8/.config/go/env'

GOEXE=''

GOEXPERIMENT=''

GOFLAGS=''

GOHOSTARCH='amd64'

GOHOSTOS='linux'

GOINSECURE=''

GOMODCACHE='/home/g4s8/go/pkg/mod'

GOOS='linux'

GOPATH='/home/g4s8/go'

GOPROXY='https://proxy.golang.org,direct'

GOROOT='/usr/lib/go'

GOSUMDB='sum.golang.org'

GOTMPDIR=''

GOTOOLCHAIN='auto'

GOTOOLDIR='/usr/lib/go/pkg/tool/linux_amd64'

GOVCS=''

GOVERSION='go1.21.0'

GCCGO='gccgo'

GOAMD64='v1'

AR='ar'

CC='gcc'

CXX='g++'

CGO_ENABLED='1'

GOMOD='/dev/null'

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 -fmessage-length=0 -ffile-prefix-map=/tmp/go-build4273986275=/tmp/go-build -gno-record-gcc-switches'

What did you do?

I'm trying to build go 1.21.0 from sources for Void Linux go package: https://github.com/void-linux/void-packages

The steps to build it (inside go repo directory):

unset GCC CC CXX LD CFLAGS
unset CGO_CXXFLAGS CGO_ENABLED

export GOROOT_FINAL=/usr/lib/go
export GOROOT=$PWD
export GOARCH=amd64

cd src
bash make.bash -v

sudo rm -f /usr/bin/go
sudo rm -fr /usr/lib/go/
sudo cp  ../bin/* -t /usr/bin
sudo cp -r .. /usr/lib/go

What did you expect to see?

When running /usr/bin/go version (or any other go command, like go build, etc) to see

go version go1.21.0 linux/amd64

What did you see instead?

When running go command or /usr/bin/go:

$ go version
go: cannot find GOROOT directory: 'go' binary is trimmed and GOROOT is not set

$ go build
go: cannot find GOROOT directory: 'go' binary is trimmed and GOROOT is not set

If I run /usr/lib/go/bin/go, then all commands works fine:

$ /usr/lib/go/bin/go version
go version go1.21.0 linux/amd64

If I run exactly the same build commands for go version 1.20.7, it's working fine:

$ go version
go version go1.20.7 linux/amd64

or

$ /usr/bin/go version
go version go1.20.7 linux/amd64

[mknyszek]

CC @bcmills @matloob via https://dev.golang.org/owners

[bcmills]

This is almost certainly a consequence of https://go.dev/cl/463740 (for #24904).

When built with -trimpath, the go command uses os.Executable to find its GOROOT, expecting that it is installed at $GOROOT/bin/go, and lots of Go programs (especially tests) expect to be able to find the go command at that location (from a configuration that gives only a GOROOT path).

@g4s8, is there a reason your script is using cp to make copies of the binaries in GOROOT/bin, instead of using ln to make /usr/bin/go a symbolic link? It seems like that would be a simpler solution, and would allow the Go toolchain installed on Void Linux to use the same reproducible binaries that are distributed through the Go project.

[bcmills]

I wonder if we should change cmd/dist to omit the -trimpath flag when GOROOT_FINAL is set.

(But I would still recommend not setting it, and using symlinks instead. 🤷‍♂️)