cmd/cgo: don't pass CGO_CFLAGS -g options to debug info generation

Fixes #26144

Change-Id: Ie69dab1bd819eaf158be11769903b2636bbcf516
Reviewed-on: https://go-review.googlesource.com/c/152165
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Nikhil Benesch <nikhil.benesch@gmail.com>

src/cmd/cgo/gcc.go

@@ -91,7 +91,13 @@ func (p *Package) addToFlag(flag string, args []string) {
 	p.CgoFlags[flag] = append(p.CgoFlags[flag], args...)
 	if flag == "CFLAGS" {
 		// We'll also need these when preprocessing for dwarf information.
-		p.GccOptions = append(p.GccOptions, args...)
+		// However, discard any -g options: we need to be able
+		// to parse the debug info, so stick to what we expect.
+		for _, arg := range args {
+			if !strings.HasPrefix(arg, "-g") {
+				p.GccOptions = append(p.GccOptions, arg)
+			}
+		}
 	}
 }
 

src/cmd/dist/test.go

@@ -1038,7 +1038,10 @@ func (t *tester) cgoTest(dt *distTest) error {
 		"linux-386", "linux-amd64", "linux-arm", "linux-ppc64le", "linux-s390x",
 		"netbsd-386", "netbsd-amd64":
 
-		t.addCmd(dt, "misc/cgo/test", t.goTest(), "-ldflags", "-linkmode=external")
+		cmd := t.addCmd(dt, "misc/cgo/test", t.goTest(), "-ldflags", "-linkmode=external")
+		// A -g argument in CGO_CFLAGS should not affect how the test runs.
+		cmd.Env = append(os.Environ(), "CGO_CFLAGS=-g0")
+
 		t.addCmd(dt, "misc/cgo/testtls", t.goTest(), "-ldflags", "-linkmode=auto")
 		t.addCmd(dt, "misc/cgo/testtls", t.goTest(), "-ldflags", "-linkmode=external")