if len(out) == 0 {
			goBuildErr = fmt.Errorf("%v: no tool reported", cmd)
			return
		}
		if _, err := exec.LookPath(string(out)); err != nil {
			goBuildErr = err
			return
		}

		if platform.MustLinkExternal(runtime.GOOS, runtime.GOARCH, false) {
			// We can assume that we always have a complete Go toolchain available.
			// However, this platform requires a C linker to build even pure Go

			os.Exit(2)
		}
		os.Exit(0)
	}

	d := t.TempDir()

	// Since we are doing a chroot, we need the binary there,
	// and it must be statically linked.
	testenv.MustHaveGoBuild(t)
	if platform.MustLinkExternal(runtime.GOOS, runtime.GOARCH, false) {
		t.Skipf("skipping: can't build static binary because %s/%s requires external linking", runtime.GOOS, runtime.GOARCH)
	}
	x := filepath.Join(d, "syscall.test")
	t.Cleanup(func() {

		// linker's build id, which will cause our build id to not
		// match the next time the tool is built.
		// Rely on the external build id instead.
		if !platform.MustLinkExternal(cfg.Goos, cfg.Goarch, false) {
			ldflags = append(ldflags, "-X=cmd/internal/objabi.buildID="+root.buildID)
		}
	}

	// Store default GODEBUG in binaries.
	if root.Package.DefaultGODEBUG != "" {