cmd/go: "go get github.com\alexbrainman\gowingui" should succeed on Mac

[alexbrainman]

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

go version go1.10 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 GOBIN=
set GOCACHE=C:\Users\Alex\AppData\Local\go-build
set GOEXE=.exe
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOOS=windows
set GOPATH=c:\users\alex\dev
set GORACE=
set GOROOT=c:\users\alex\dev\go
set GOTMPDIR=
set GOTOOLDIR=c:\users\alex\dev\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\Alex\AppData\Local\Temp\go-build838310042=/tmp/go-build -gno-record-gcc-switches

What did you do?

I run

go get github.com\alexbrainman\gowingui

command.

What did you expect to see?

I expected command to fail, because I used \ instead of / in package import path.

What did you see instead?

I see no error message, and I also see gowingui.exe in my %GOPATH%\bin directory.

Comments

I discovered this while investigating #24232

And if I run

go install -ldflags "-H windowsgui" github.com\alexbrainman\gowingui

the %GOPATH%\bin\gowingui.exe file does not have IMAGE_SUBSYSTEM_WINDOWS_GUI flag set properly.

So if this issue is rejected as working as intended, than we should fix cmd/go flag processing to avoid cases like #24232

Alex

[ysmolski]

Windows:

C:\Users\thorn>go get -v github.com\alexbrainman\gowingui
github.com/alexbrainman/gowingui (download)

Mac:

thorn@t2 ...go/src/playground % go get -v 'gitfhub.com\alexbrainman\gowingui'
https fetch failed: parse https://gitfhub.com\alexbrainman\gowingui: invalid character "\\" in host name

This happens in ImportPathsNoDotExpansion function
https://github.com/golang/go/blob/master/src/cmd/go/internal/load/search.go#L360-L362

which is called by downloadPaths: https://github.com/golang/go/blob/master/src/cmd/go/internal/get/get.go#L172

On windows go get silently fixes \ into / which is the right thing, but as a side effect, it applies the same fix to URLs. Which again could be a good thing because Chrome browser does exactly the same thing.

There is an inconsistency in behaviour between OSes with fileseparator = \ and other Oses. I don't know if it should be fixed.

[bradfitz]

I'm pretty sure we should fix this, but marking it as needs decision just in case. @ianlancetaylor, @rsc?

[rsc]

I agree.

[bcmills]

The fact that the backslashes work on Windows is intentional and not actually Windows-specific:

go/src/cmd/go/internal/search/search.go

Lines 352 to 357 in 5a7cfbc

	// Arguments are supposed to be import paths, but
	// as a courtesy to Windows developers, rewrite \ to /
	// in command-line arguments. Handles .\... and so on.
	if filepath.Separator == '\\' {
	a = strings.ReplaceAll(a, `\`, `/`)
	}

We should figure out why they don't work on macOS.