// Build a regexp that matches any prefix of the exit string at the end of
	// the input. We do it this way to avoid assuming anything about the
	// subcommand output (e.g., it might not be \n-terminated).
	var exitReStr strings.Builder
	for i := 1; i <= len(exitStr); i++ {
		fmt.Fprintf(&exitReStr, "%s$|", exitStr[:i])
	}
	// Finally, match the exit string along with an exit code.

	fmt.Fprintf(w, "\tfile:line\n")
}

func usage() {
	printUsage(os.Stderr)
	os.Exit(2)
}

func main() {
	log.SetFlags(0)
	log.SetPrefix("addr2line: ")

	// pprof expects this behavior when checking for addr2line
	if len(os.Args) > 1 && os.Args[1] == "--help" {
		printUsage(os.Stdout)
		os.Exit(0)
	}

	flag.Usage = usage
	flag.Parse()
	if flag.NArg() != 1 {
		usage()
	}

	case "Call":
		testCall()
	case "Callback":
		testCallback()
	}
	println("OK")
}

func fatal(f string, args ...any) {
	fmt.Fprintln(os.Stderr, fmt.Sprintf(f, args...))
	os.Exit(1)
}

type GoCallback struct{}

func (p *GoCallback) Run() string {
	return "GoCallback.Run"
}

func testCall() {
	c := NewCaller()
	cb := NewCallback()

	c.SetCallback(cb)
	s := c.Call()

	ctxt.Debugpcln = flags.DebugFlags.PCTab
	ctxt.IsAsm = true
	ctxt.Pkgpath = *flags.Importpath
	switch *flags.Spectre {
	default:
		log.Printf("unknown setting -spectre=%s", *flags.Spectre)
		os.Exit(2)
	case "":
		// nothing
	case "index":
		// known to compiler; ignore here so people can use
		// the same list with -gcflags=-spectre=LIST and -asmflags=-spectrre=LIST
	case "all", "ret":
		ctxt.Retpoline = true

		fatal("read unexpected characters")
	}
	if Fclose(f) != 0 {
		fatal("fclose failed")
	}

	println("OK")
}

func fatal(f string, args ...any) {
	fmt.Fprintln(os.Stderr, fmt.Sprintf(f, args...))
	os.Exit(1)