cmd/go: flag validation fails when pkg-config --libs reports a path containing spaces

[CannibalVox]

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

$ go version
go version go1.13.1 windows/amd64

Does this issue reproduce with the latest release?

Yes

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

go env Output

$ go env
set GO111MODULE=
set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\Stephen Baynham\AppData\Local\go-build
set GOENV=C:\Users\Stephen Baynham\AppData\Roaming\go\env
set GOEXE=.exe
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=C:\Users\Stephen Baynham\go
set GOPRIVATE=
set GOPROXY=https://proxy.golang.org,direct
set GOROOT=c:\go
set GOSUMDB=sum.golang.org
set GOTMPDIR=
set GOTOOLDIR=c:\go\pkg\tool\windows_amd64
set GCCGO=gccgo
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=C:\Users\Stephen Baynham\source\repos\go-luajit\go.mod
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\STEPHE~1\AppData\Local\Temp\go-build884938030=/tmp/go-build -gno-record-gcc-switches

What did you do?

Place the -L directory of a C lib into a directory with a space in it, and access it a pkg-config .pc file.

/*
#cgo pkg-config: luajit
#include "go_luajit.h"
*/
import "C"

func main() {}

Attempt to build:

$ pkg-config --cflags luajit
-IC:/Program\ Files/Git/usr/local/include/luajit-2.0

$ pkg-config --libs luajit
-LC:/Program\ Files/Git/usr/local/lib -lluajit-5.1

$ go build ./...
go build github.com/cannibalvox/luajitter: invalid flag in pkg-config --libs: Files/Git/usr/local/lib

What did you expect to see?

Successful build.

What did you see instead?

go build github.com/cannibalvox/luajitter: invalid flag in pkg-config --libs: Files/Git/usr/local/lib

Context

In 2016, this issue was brought up and was successfully solved, but only for CFlags: #16455

Commit: https://go-review.googlesource.com/c/go/+/32735/6/src/cmd/go/build.go

However, on windows where the (git bash) mingw /usr directory is in C:\Program Files, both the include and lib directories have spaces in them. In issue 16455, it was determined to wait on windows until more information was provided. However, the linked commit fixes linux as well as windows. The only problem is that the fix was only applied to CFLAGS and not LDFLAGS. Having LDFLAGS also use splitPkgConfigOutput instead of strings.Fields would solve this problem entirely. Are there any considerations that might prevent me from PRing a straight 1:1 replacement?

[bcmills]

CC @ianlancetaylor @jayconrod

[bcmills]

Are there any considerations that might prevent me from PRing a straight 1:1 replacement?

I'm not aware of any. Send a PR (and, ideally, a regression test) and we can discuss on the code review?

[gopherbot]

Change https://golang.org/cl/209437 mentions this issue: cmd/go: make cgo pkg-config work w/ lib paths that have spaces

[gopherbot]

Change https://go.dev/cl/466875 mentions this issue: cmd/go: handle escapes in pkg-config ldflags output

[gopherbot]

Change https://go.dev/cl/466864 mentions this issue: cmd/go: fuzz test splitPkgConfigOutput and fix minor bugs

[gopherbot]

Change https://go.dev/cl/473616 mentions this issue: cmd/go: trim spaces in pkg-config ldflags output