cmd/go: should not depend on the existence of the default $GOROOT

[ghost]

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

1.8

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

linux/amd64

What did you do?

I downloaded go1.8.linux-amd64.tar.gz and extracted it into the home directory and did export PATH="/home/user/go/bin:$PATH". Then I tried to run go version.

What did you expect to see?

Go version number.

What did you see instead?

go: cannot find GOROOT directory: /usr/local/go

None of the commands build, fmt, generate, get, install, list, run, test, vet etc. do work. They all print the same error.

When I create an empty /usr/local/go, they all by some magic start to work.

[ALTree]

Did you manually set GOROOT?

[ghost]

I didn't. The problem occurs without explicitly set GOROOT environment variable. And if I set it to /home/user/go (the location where I've unpacked the archive), things also work (unsurprisingly).

[ALTree]

Please post the output of go env. Also what does echo $GOROOT print?

[ghost]

Please post the output of go env.

With unexported GOROOT:

$ export -n GOROOT
$ go env
go: cannot find GOROOT directory: /usr/local/go

With GOROOT set to /home/opennota/go:

$ export GOROOT=/home/opennota/go
$ go env
GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH=""
GORACE=""
GOROOT="/home/opennota/go"
GOTOOLDIR="/home/opennota/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build941069124=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"

Also what does echo $GOROOT print?

Nothing, if GOROOT is not set. /home/opennota/go, it if is.

[ALTree]

I'm not sure there's anything do to here.

The GOROOT default value is baked in the executable, so if you download the precompiled binaries you'll always have /usr/local/go baked in. If you put go in another directory, you must set GOROOT (otherwise nothing will work). This is documented:

$GOROOT [..] Its value is built into the tree when it is compiled

and:

It is possible to install the Go tools to a different location. In this case you must set the GOROOT environment variable to point to the directory in which it was installed.

If you don't want /usr/local/go to be baked in the executable, you'll have to compile from source.

[ianlancetaylor]

Closing as dup of #17833.