path/filepath: TestEvalSymlinks tests with "/" prefix fail in Windows

[JoshVarga]

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

go version go1.10.1 windows/amd64

Does this issue reproduce with the latest release?

Yes

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

set GOARCH=amd64
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOOS=windows

What did you do?

Built go using "all.bat"

What did you expect to see?

while running tests
ok path/filepath x.xxxs

What did you see instead?

--- FAIL: TestEvalSymlinks (0.04s)
path_test.go:798: EvalSymlinks("C:\Users\varga\AppData\Local\Temp\evalsymlink400713581\test/linkabs") returns "C:\", want "/"
FAIL
FAIL path/filepath 1.552s

I have a code fix for this if this. Essentially just prepending the expected result with the volume name if we are on Windows and the path has a prefix of "/".

Does that sound reasonable?

[agnivade]

/cc @alexbrainman

[gopherbot]

Change https://golang.org/cl/106975 mentions this issue: path/filepath: TestEvalSymlinks tests with "/" prefix fail in Windows

[alexbrainman]

@JoshVarga I cannot reproduce this. How do I reproduce this?

You say you are using go1.10.1. But you error message

--- FAIL: TestEvalSymlinks (0.04s)
path_test.go:798: EvalSymlinks("C:\Users\varga\AppData\Local\Temp\evalsymlink400713581\test/linkabs") returns "C:", want "/"
FAIL
FAIL path/filepath 1.552s

does not match the code https://github.com/golang/go/blob/go1.10.1/src/path/filepath/path_test.go#L798 Why?

Please provide more details about your environment so I can try and reproduce it here: go env output, Windows version, value of %TMP% and everything else you think might be useful.

Thank you.

Alex

[JoshVarga]

I don't think there is a bug in Go just in the test. I believe it is because filepath.Clean reduces the root for a Windows path to C:\ for example but it will not add a volume name onto a path like "/" (that was used in the test).

1.10.1 is my bootstrap compiler to build tip source. I boiled down the code from path_test.go so that it reproduces the issue compiling in 1.10.1 as simple as possible.

package main

import (
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
)

func simpleJoin(dir, path string) string {
	return dir + string(filepath.Separator) + path
}

func testEvalSymlinks(path, want string) {
	have, err := filepath.EvalSymlinks(path)
	if err != nil {
		panic(fmt.Sprintf("EvalSymlinks(%q) error: %v", path, err))
		return
	}
	if filepath.Clean(have) != filepath.Clean(want) {
		panic(fmt.Sprintf("EvalSymlinks(%q) returns %q, want %q", path, have, want))
	}
}

func main() {
	tmpDir, err := ioutil.TempDir("", "evalsymlink")
	if err != nil {
		panic(fmt.Sprintf("creating temp dir:", err))
	}
	defer os.RemoveAll(tmpDir)
	tmpDir, err = filepath.EvalSymlinks(tmpDir)
	if err != nil {
		panic(fmt.Sprintf("eval symlink for tmp dir:", err))
	}
	path := simpleJoin(tmpDir, "test")
	err = os.Mkdir(path, 0755)
	if err != nil {
		panic(err)
	}
	path = simpleJoin(tmpDir, "test/linkabs")
	err = os.Symlink("/", path)
	if err != nil {
		panic(err)
	}
	testEvalSymlinks(path, "/")
}

This is my full go env

set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\varga\AppData\Local\go-build
set GOEXE=.exe
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOOS=windows
set GOPATH=E:\GoCode\
set GORACE=
set GOROOT=E:\go
set GOTMPDIR=
set GOTOOLDIR=E:\go\pkg\tool\windows_amd64
set GCCGO=gccgo
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0 -fdebug-prefix-map=C:\Users\varga\AppData\Local\Temp\go-build005706398=/tmp/go-build -gno-record-gcc-switches

When run the above code on my Windows 10 Pro machine I get:

panic: EvalSymlinks("C:\\Users\\varga\\AppData\\Local\\Temp\\evalsymlink097815331\\test/linkabs") returns "C:\\", want "/"

goroutine 1 [running]:
main.testEvalSymlinks(0xc04209c0f0, 0x43, 0x4d7e78, 0x1)
        E:/GoCode/src/github.com/JoshVarga/evalsym/main.go:21 +0x2ce
main.main()
        E:/GoCode/src/github.com/JoshVarga/evalsym/main.go:45 +0x23a

As requested here is my %TMP%

E:\gocode\src\github.com\JoshVarga\evalsym>ECHO %TMP%
C:\Users\varga\AppData\Local\Temp

[alexbrainman]

@JoshVarga thank you for providing your environment details. I can reproduce your problem now. The important difference between your setup and mine is that your GOROOT directory lives on the different drive from your TMP directory.

I think we need to adjust the test to accommodate for that scenario. I have not decided what to do yet. I will think about this when I have free time.

Alex