}

func run(t *testing.T, dir string, lto bool, args ...string) {
	runArgs := append([]string{"run", "."}, args...)
	cmd := exec.Command("go", runArgs...)
	cmd.Dir = dir
	if lto {
		const cflags = "-flto -Wno-lto-type-mismatch -Wno-unknown-warning-option"
		cmd.Env = append(cmd.Environ(),
			"CGO_CFLAGS="+cflags,
			"CGO_CXXFLAGS="+cflags,
			"CGO_LDFLAGS="+cflags)
	}
	out, err := cmd.CombinedOutput()
	if string(out) != "OK\n" {

	}

	newID := id[:strings.LastIndex(id, "/")] + "/" + buildid.HashToString(hash)
	if len(newID) != len(id) {
		log.Fatalf("%s: build ID length mismatch %q vs %q", file, id, newID)
	}

	if len(matches) == 0 {
		return
	}

	f, err = os.OpenFile(file, os.O_RDWR, 0)
	if err != nil {
		log.Fatal(err)
	}

// the zero value is a crash.  To bridge the gap, the
// init bool says whether this is a valid gmp value.
// doinit initializes z.i if it needs it.  This is not inherent
// to FFI, just a mismatch between Go's convention of
// making zero values useful and gmp's decision not to.
func (z *Int) doinit() {
	if z.init {
		return
	}
	z.init = true
	C.mpz_init(&z.i[0])
}