cmd/go, cmd/link: if -no-pie doesn't work, try -nopie

GCC says -no-pie, clang says -nopie.

Fixes #21042

Change-Id: Iadc83ea7a48ea0debc5064c1ee8da4ebff752044
Reviewed-on: https://go-review.googlesource.com/49710
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/go/internal/work/build.go

@@ -2948,8 +2948,8 @@ func (tools gccgoToolchain) link(b *Builder, root *Action, out string, allaction
 		// libffi.
 		ldflags = append(ldflags, "-Wl,-r", "-nostdlib", "-Wl,--whole-archive", "-lgolibbegin", "-Wl,--no-whole-archive")
 
-		if b.gccSupportsNoPie() {
-			ldflags = append(ldflags, "-no-pie")
+		if nopie := b.gccNoPie(); nopie != "" {
+			ldflags = append(ldflags, nopie)
 		}
 
 		// We are creating an object file, so we don't want a build ID.
@@ -3196,11 +3196,18 @@ func (b *Builder) ccompilerCmd(envvar, defcmd, objdir string) []string {
 	return a
 }
 
-// On systems with PIE (position independent executables) enabled by default,
-// -no-pie must be passed when doing a partial link with -Wl,-r. But -no-pie is
-// not supported by all compilers.
-func (b *Builder) gccSupportsNoPie() bool {
-	return b.gccSupportsFlag("-no-pie")
+// gccNoPie returns the flag to use to request non-PIE. On systems
+// with PIE (position independent executables) enabled by default,
+// -no-pie must be passed when doing a partial link with -Wl,-r.
+// But -no-pie is not supported by all compilers, and clang spells it -nopie.
+func (b *Builder) gccNoPie() string {
+	if b.gccSupportsFlag("-no-pie") {
+		return "-no-pie"
+	}
+	if b.gccSupportsFlag("-nopie") {
+		return "-nopie"
+	}
+	return ""
 }
 
 // gccSupportsFlag checks to see if the compiler supports a flag.
@@ -3531,8 +3538,8 @@ func (b *Builder) collect(p *load.Package, obj, ofile string, cgoLDFLAGS, outObj
 
 	ldflags = append(ldflags, "-Wl,-r", "-nostdlib")
 
-	if b.gccSupportsNoPie() {
-		ldflags = append(ldflags, "-no-pie")
+	if flag := b.gccNoPie(); flag != "" {
+		ldflags = append(ldflags, flag)
 	}
 
 	// We are creating an object file, so we don't want a build ID.

src/cmd/link/internal/ld/lib.go

@@ -1255,13 +1255,20 @@ func (l *Link) hostlink() {
 		if err := ioutil.WriteFile(src, []byte{}, 0666); err != nil {
 			Errorf(nil, "WriteFile trivial.c failed: %v", err)
 		}
-		cmd := exec.Command(argv[0], "-c", "-no-pie", "trivial.c")
-		cmd.Dir = *flagTmpdir
-		cmd.Env = append([]string{"LC_ALL=C"}, os.Environ()...)
-		out, err := cmd.CombinedOutput()
-		supported := err == nil && !bytes.Contains(out, []byte("unrecognized"))
-		if supported {
-			argv = append(argv, "-no-pie")
+
+		// GCC uses -no-pie, clang uses -nopie.
+		for _, nopie := range []string{"-no-pie", "-nopie"} {
+			cmd := exec.Command(argv[0], "-c", nopie, "trivial.c")
+			cmd.Dir = *flagTmpdir
+			cmd.Env = append([]string{"LC_ALL=C"}, os.Environ()...)
+			out, _ := cmd.CombinedOutput()
+			// GCC says "unrecognized command line option ‘-no-pie’"
+			// clang says "unknown argument: '-no-pie'"
+			supported := !bytes.Contains(out, []byte("unrecognized")) && !bytes.Contains(out, []byte("unknown"))
+			if supported {
+				argv = append(argv, nopie)
+				break
+			}
 		}
 	}