x/build/version: runtime.GOROOT() returns /usr/local/go instead of ~/sdk/go1.9rc2

[stapelberg]

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

go version go1.9rc2 linux/amd64

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

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/michael/go"
GORACE=""
GOROOT="/home/michael/sdk/go1.9rc2"
GOTOOLDIR="/home/michael/sdk/go1.9rc2/pkg/tool/linux_amd64"
GCCGO="/usr/bin/gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build189329817=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"

What did you do?

% go get -u golang.org/x/build/version/go1.9rc2
% go1.9rc2 download
Downloaded 0.0% (15232 / 98420498 bytes) ...
Downloaded 8.6% (8421376 / 98420498 bytes) ...
Downloaded 22.3% (21953564 / 98420498 bytes) ...
Downloaded 100.0% (98420498 / 98420498 bytes)
Unpacking /home/michael/sdk/go1.9rc2/go1.9rc2.linux-amd64.tar.gz ...
Success. You may now run 'go1.9rc2'
% go1.9rc2 run runtime.go  
2017/08/11 09:04:58 $GOROOT = "/home/michael/sdk/go1.9rc2"
2017/08/11 09:04:58 /home/michael/sdk/go1.9rc2
% go1.9rc2 build runtime.go && ./runtime
2017/08/11 09:05:15 $GOROOT = ""
2017/08/11 09:05:15 /usr/local/go
% cat runtime.go
package main

import (
	"log"
	"os"
	"runtime"
)

func main() {
	log.Printf("$GOROOT = %q\n", os.Getenv("GOROOT"))
	log.Println(runtime.GOROOT())
}

What did you expect to see?

runtime.GOROOT() should always return /home/michael/sdk/go1.9rc2

What did you see instead?

runtime.GOROOT() returned /usr/local/go, which is set in ~/sdk/go1.9rc2/src/runtime/internal/sys/zversion.go

Issue #18136 mentions a build flag (having the tool compile Go on my machine seems like it should fix the issue), but I couldn’t find that — AFAICT, the go1.9rc2 command only supports the “download” flag.

cc @bradfitz

[ALTree]

Thanks for the report.

This is a duplicate of #21313 (runtime: bad GOROOT in 1.9rc1), so I'm closing this thread in favour of the older one.