x/tools/cmd/guru: GOROOT needs to be set for guru

[yaojingguo]

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

go version go1.9.1 darwin/amd64

Does this issue reproduce with the latest release?

yes

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

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/jing/go"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/qd/wj_djys9219cyj4l9c2qw6g80000gn/T/go-build712584400=/tmp/go-build -gno-record-gcc-switches -fno-common"
CXX="clang++"
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"

Steps to reproduce the problem

I had installed go 1.8.3 in /usr/local/Cellar/go/1.8.3/libexec with brew before. But I had uninstalled it and installed Go 1.9.1.

I checked that GOROOT was unset in the terminal with echo $GOROOT. Then I ran guru definition main.go:#56. But guru said guru: cannot find package "fmt" . Here is the terminal session details:

➜  cockroach git:(master) ✗ echo $GOROOT

➜  cockroach git:(master) ✗ guru definition main.go:#56
guru: cannot find package "fmt" in any of:
	/Users/jing/go/src/github.com/cockroachdb/cockroach/vendor/fmt (vendor tree)
	/usr/local/Cellar/go/1.8.3/libexec/src/fmt (from $GOROOT)
	/Users/jing/go/src/fmt (from $GOPATH)
➜  cockroach git:(master) ✗

Then I ran export GOROOT=/usr/local/go in the same terminal. And then running guru definition main.go:#56 produced:

/usr/local/go/src/fmt/print.go:256:6: defined here as func fmt.Println

main.go is on https://play.golang.org/p/eEZMXonMhA.

And rogpeppe/godef#73 is a similar problem.

[cznic]

I guess your environment variable GOROOT, if set, points to a wrong location. If it is not set, I guess the Go installation was made to a wrong place. It thinks it's in /usr/local/Cellar/go/1.8.3/libexec/, but you say it was installed in /usr/local/Cellar/go/1.8.3/ instead.

And finally, the workaround indicates that Go was perhaps actually installed in /usr/local/go/. The guesses are mutually exclusive, I think your current Go installation is somehow a corrupted mix of more than one installation.

Also trying to set GOPATH to point to GOROOT is probably not going to work well.

[yaojingguo]

@cznic I have made several mistakes in my comment. Sorry for that. GOPATH should be GOROOT. And Go 1.8.3 was in /usr/local/Cellar/go/1.8.3/libexec before I uninstalled it.

I have updated my original comment.

[ianlancetaylor]

CC @alandonovan

I assume that you built guru yourself, and that it captured the setting of GOROOT used by the tools used to build it. Then you moved your installation, so guru was using the old GOROOT and was not finding anything in the new GOROOT.

I have not looked at the code, but perhaps guru should run go env GOROOT to determine the GOROOT value to use, rather than calling runtime.GOROOT. If that sounds right to @alandonovan , would you like to send a patch?

[dominikh]

This sounds strongly related to #22303, and affects all static analysis tools.

[yaojingguo]

@ianlancetaylor yes, sure

[natefinch]

@dominikh - definitely the same problem.

@yaojingguo - if you want to avoid setting GOROOT, you can also rebuild the guru with your current set up, which will detect & embed the new (correct) GOROOT.

[yaojingguo]

@natefinch Thanks. Rebuilding guru works.

[stamblerre]

Closing, as setting GOROOT is no longer needed with more recent versions of Go.

More context can be found in golang/vscode-go#146, and @hyangah has confirmed that it is no longer necessary to recompile tools when the Go version changes. Furthermore, guru is no longer maintained.