    // errors/warnings   std::ifstream stderr_stream(stderr_file());   error_parse(stderr_stream, result==0, message);    if(result!=0)   {     message.error() << "Preprocessing failed" << messaget::eom;     return true;   }    return false; }  /// ANSI-C preprocessing bool c_preprocess_gcc_clang(   const std::string &file,   std::ostream &outstream,   message_handlert &message_handler