在编译协议缓冲区生成的源文件时,是否有更好的方法来解决警告？

Question

对于一个简单的proto文件:

message Person {
  required int32 id = 1;
  required string name = 2;
  optional string email = 3;
}

它是由protoc.exe编译的,结果用于一个简单的测试项目,除了包括protoc生成的文件之外什么也没做.

我正在使用msvc10来构建测试项目(x64),然后它给了我很多警告:

Warning 1   warning C4244: 'return' : conversion from '__int64' to 'int', possible loss of data D:\Work\protobuf-trunk\src\google\protobuf\descriptor.h 1441    1   testProtobuf
...
Warning 11  warning C4267: 'argument' : conversion from 'size_t' to 'int', possible loss of data    D:\Work\protobuf-trunk\src\google\protobuf\unknown_field_set.h  142 1   testProtobuf
Warning 12  warning C4267: 'return' : conversion from 'size_t' to 'int', possible loss of data  D:\Work\protobuf-trunk\src\google\protobuf\unknown_field_set.h  237 1   testProtobuf
...
Warning 14  warning C4244: '=' : conversion from '__int64' to 'int', possible loss of data  D:\Work\protobuf-trunk\src\google\protobuf\io\coded_stream.h    902 1   testProtobuf
Warning 15  warning C4244: 'return' : conversion from '__int64' to 'int', possible loss of data D:\Work\protobuf-trunk\src\google\protobuf\io\coded_stream.h    1078    1   testProtobuf
Warning 16  warning C4267: 'argument' : conversion from 'size_t' to 'google::protobuf::uint32', possible loss of data   D:\Work\protobuf-trunk\src\google\protobuf\wire_format_lite_inl.h   663 1   testProtobuf
...
Warning 19  warning C4267: 'return' : conversion from 'size_t' to 'int', possible loss of data  D:\Work\protobuf-trunk\src\google\protobuf\wire_format_lite_inl.h   739 1   testProtobuf
Warning 20  warning C4267: 'argument' : conversion from 'size_t' to 'google::protobuf::uint32', possible loss of data   D:\Work\protobuf-trunk\src\google\protobuf\wire_format_lite_inl.h   742 1   testProtobuf
Warning 21  warning C4267: 'return' : conversion from 'size_t' to 'int', possible loss of data  D:\Work\protobuf-trunk\src\google\protobuf\wire_format_lite_inl.h   743 1   testProtobuf
Warning 22  warning C4267: 'argument' : conversion from 'size_t' to 'int', possible loss of data    D:\Work\testProtobuf\testProtobuf\person.pb.cc  211 1   testProtobuf
...
Warning 28  warning C4996: 'std::_Copy_impl': Function call with parameters that may be unsafe - this call relies on the caller to check that the passed values are correct. To disable this warning, use -D_SCL_SECURE_NO_WARNINGS. See documentation on how to use Visual C++ 'Checked Iterators' C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\xutility 2239    1   testProtobuf
Warning 29  warning C4996: 'std::_Copy_impl': Function call with parameters that may be unsafe - this call relies on the caller to check that the passed values are correct. To disable this warning, use -D_SCL_SECURE_NO_WARNINGS. See documentation on how to use Visual C++ 'Checked Iterators' C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\xutility 2239    1   testProtobuf

有没有什么好方法可以解决所有这些警告？任何建议将不胜感激.

PS.libprotobuf项目本身可以由msvc10清理编译,没有任何警告.

[ 编辑2013/02/20 ]

工作方案:

1. 设置protoc生成的.cc文件的
   属性: 配置属性 - > c/c ++ - >高级 - >禁用特定警告

Answer 1

你可以破解protoc编译器的源代码,让它自动将pragma注入到生成的文件中.

在第94行附近的src/google/protobuf/compiler/cpp/cpp_file.cc中GenerateHeader(io::Printer* printer),将第一个printer->Print调用更改为:

  // Generate top of header.
  printer->Print(
    "// Generated by the protocol buffer compiler.  DO NOT EDIT!\n"
    "// source: $filename$\n"
    "\n"
    "#ifndef PROTOBUF_$filename_identifier$__INCLUDED\n"
    "#define PROTOBUF_$filename_identifier$__INCLUDED\n"
    "\n"
    "#ifdef _MSC_VER\n"
    "#  pragma warning(push)\n"
    "#  pragma warning(disable: 4127 4244 4267)\n"
    "#endif\n"
    "\n"
    "#include <string>\n"
    "\n",
    "filename", file_->name(),
    "filename_identifier", filename_identifier);

然后在第294行左右的同一函数的末尾,将最后一次printer->Print调用更改为:

  printer->Print(
    "#ifdef _MSC_VER\n"
    "#  pragma warning(pop)\n"
    "#endif\n"
    "\n"
    "#endif  // PROTOBUF_$filename_identifier$__INCLUDED\n",
    "filename_identifier", filename_identifier);

现在您只需要编译protoc目标并运行新的protoc.exe以在生成的头文件中包含pragma.

Answer 2

一个简单的方法是使用包装头来包含生成的 protobuf 头：

#ifndef MESSAGES_WRAPPER_H
#define MESSAGES_WRAPPER_H

#ifdef _MSC_VER
  #pragma warning(push)
  #pragma warning(disable: 4018 4100 4267)
#endif

#include "messages.pb.h"

#ifdef _MSC_VER
  #pragma warning(pop)
#endif

#endif // MESSAGES_WRAPPER_H