tg := testgo(t)
	defer tg.cleanup()
	tg.parallel()
	tg.tempFile("main.go", `package main
		import "crypto/sha1"
		func main() {
			sha1.New()
		}`)
	tg.run("build", "-ldflags=-w -extld=false", tg.path("main.go"))
	tg.run("build", "-ldflags=-extld=false", tg.path("main.go"))

		t.Skipf("skipping on %s/%s: no DWARF symbol table in executables", runtime.GOOS, runtime.GOARCH)
	}

	if runtime.GOOS == "aix" {
		extld := os.Getenv("CC")
		if extld == "" {
			extld = "gcc"
		}
		extldArgs, err := quoted.Split(extld)
		if err != nil {
			t.Fatal(err)
		}
		enabled, err := cmddwarf.IsDWARFEnabledOnAIXLd(extldArgs)
		if err != nil {
			t.Fatal(err)
		}
		if !enabled {

	for _, prog := range []string{"testprog", "testprogcgo"} {
		prog := prog
		expectDWARF := expectDWARF
		if runtime.GOOS == "aix" && prog == "testprogcgo" {
			extld := os.Getenv("CC")
			if extld == "" {
				extld = "gcc"
			}
			extldArgs, err := quoted.Split(extld)
			if err != nil {
				t.Fatal(err)
			}
			expectDWARF, err = cmddwarf.IsDWARFEnabledOnAIXLd(extldArgs)
			if err != nil {
				t.Fatal(err)
			}
		}

		system tools now assume the presence of the header.
	-dumpdep
		Dump symbol dependency graph.
	-extar ar
		Set the external archive program (default "ar").
		Used only for -buildmode=c-archive.
	-extld linker
		Set the external linker (default "clang" or "gcc").
	-extldflags flags
		Set space-separated flags to pass to the external linker.
	-f
		Ignore version mismatch in the linked archives.
	-g

	for _, f := range ldflags {
		if f == "-extld" || strings.HasPrefix(f, "-extld=") {
			// don't override -extld if supplied
			return ldflags, nil
		}
	}
	joined, err := quoted.Join(compiler)
	if err != nil {
		return nil, err
	}
	return append(ldflags, "-extld="+joined), nil
}

// pluginPath computes the package path for a plugin main package.
//

// It returns library full path if found, or "none" if not found.
func (ctxt *Link) findLibPathCmd(cmd, libname string) string {
	extld := ctxt.extld()
	name, args := extld[0], extld[1:]
	args = append(args, hostlinkArchArgs(ctxt.Arch)...)
	args = append(args, cmd)
	if ctxt.Debugvlog != 0 {
		ctxt.Logf("%s %v\n", extld, args)
	}
	out, err := exec.Command(name, args...).Output()
	if err != nil {
		if ctxt.Debugvlog != 0 {

// IsDWARFEnabledOnAIXLd returns true if DWARF is possible on the
// current extld.
// AIX ld doesn't support DWARF with -bnoobjreorder with version
// prior to 7.2.2.
func IsDWARFEnabledOnAIXLd(extld []string) (bool, error) {
	name, args := extld[0], extld[1:]
	args = append(args, "-Wl,-V")
	out, err := exec.Command(name, args...).CombinedOutput()
	if err != nil {

	ownTmpDir      bool // set to true if tmp dir created by linker (e.g. no -tmpdir)
)

func init() {
	flag.Var(&rpath, "r", "set the ELF dynamic linker search `path` to dir1:dir2:...")
	flag.Var(&flagExtld, "extld", "use `linker` when linking in external mode")
	flag.Var(&flagExtldflags, "extldflags", "pass `flags` to external linker")
	flag.Var(&flagW, "w", "disable DWARF generation")
}

into fields, or else "gcc". The specific host linker command line can
be overridden using command line flags: cmd/link -extld=clang
-extldflags='-ggdb -O3'. If any package in a build includes a .cc or
other file compiled by the C++ compiler, the go tool will use the
-extld option to set the host linker to the C++ compiler.

These defaults mean that Go-aware build systems can ignore the linking

		}
		link = []string{pathf("%s/link", tooldir)}
		if goos == "android" {
			link = append(link, "-buildmode=pie")
		}
		if goldflags != "" {
			link = append(link, goldflags)
		}
		link = append(link, "-extld="+compilerEnvLookup("CC", defaultcc, goos, goarch))
		link = append(link, "-L="+pathf("%s/pkg/obj/go-bootstrap/%s_%s", goroot, goos, goarch))
		link = append(link, "-o", pathf("%s/%s%s", tooldir, elem, exe))
		targ = len(link) - 1