func ToAST(name string, options ...Option) (AST, error) {
	if strings.HasPrefix(name, "_Z") {
		a, err := doDemangle(name[2:], options...)
		return a, adjustErr(err, 2)
	}

	if strings.HasPrefix(name, "___Z") {
		// clang extensions
		block := strings.LastIndex(name, "_block_invoke")
		if block == -1 {
			return nil, ErrNotMangledName
		}
		a, err := doDemangle(name[4:block], options...)
		if err != nil {