Merge "Fix return-stack-address warning"

    int getError() { return static_cast<int>(error_); }

    const string& GenerateMessage(int size) {

    const string GenerateMessage(int size) {

        for (const string& message : message_cache_) {

            if (message.size() == size) {

                return message;

        }

        string message = string(size, 'x');

        message_cache_.push_back(message);

        return std::move(message);

        return message;

    }

    optional<BlockMode> getBlockMode(string transform) {