如何指定vc11 lambda调用约定 [英] how to specify vc11 lambda calling convention

问题描述

我想通过一个lambda函数指针，它嵌套在一个班，对Windows API的回调函数。我发现没有地方可以指定 __ stdcall 关键字。我用nm命令有人告诉我，编译只支持 __ CDECL ，但经过转储obj的文件，我发现编译将产生三个辅助函数（ __ stdcall ， __ cdecl ， __ fastcall ）。所以我的问题是，我怎么可以指定调用约定？

那些下面的代码是我的测试代码。

 的#includestdafx.h中
 INT _tmain（INT ARGC，_TCHAR *的argv []）
 {
自动FUNC = []（）{ }; 
 return 0; 
} 
  

  0000万吨< helper_func_cdecl> @< lambda_5738939ec88434c53e1a446c47cf2db6> @@ CAXXZ 
 0000万吨< helper_func_fastcall> @< lambda_5738939ec88434c53e1a446c47cf2db6> @@ CIXXZ 
 0000万吨< helper_func_stdcall> @< lambda_5738939ec88434c53e1a446c47cf2db6> @@ CGXXZ 
 0000万吨?? b< lambda_5738939ec88434c53e1a446c47cf2db6> @@ QBEP6AXXZXZ 
 0000万吨?? b< lambda_5738939ec88434c53e1a446c47cf2db6> @@ QBEP6GXXZXZ 
 0000万吨?? b< lambda_5738939ec88434c53e1a446c47cf2db6> @@ QBEP6IXXZXZ 
 0000万吨?? R< lambda_5738939ec88434c53e1a446c47cf2db6> @@ QBEXXZ 
  

解决方案

演员吧：

  WinApiFunc（的static_cast<无效（__ STDCALL *）（）>（FUNC））; 
  

或者先将其存储到本地变量中：

  void（__stdcall * funcp）（）= func; 
 WinApiFunc（funcp）; 
  

I want to pass a lambda function pointer, which nested in a class, to the Windows API callback function. I found there is no place for me to specify the __stdcall keyword. Some people told me the compile only support __cdecl, but after I used nm command to dump the obj file, I found the compile will generate three helper function (__stdcall, __cdecl, __fastcall) concurrently. So my problem is, how can I specify the calling convention?

Those following code are my test code.

#include "stdafx.h"
int _tmain(int argc, _TCHAR* argv[])
{
    auto func = [](){};
    return 0;
}

00000000 t ?<helper_func_cdecl>@<lambda_5738939ec88434c53e1a446c47cf2db6>@@CAXXZ
00000000 t ?<helper_func_fastcall>@<lambda_5738939ec88434c53e1a446c47cf2db6>@@CIXXZ
00000000 t ?<helper_func_stdcall>@<lambda_5738939ec88434c53e1a446c47cf2db6>@@CGXXZ
00000000 t ??B<lambda_5738939ec88434c53e1a446c47cf2db6>@@QBEP6AXXZXZ
00000000 t ??B<lambda_5738939ec88434c53e1a446c47cf2db6>@@QBEP6GXXZXZ
00000000 t ??B<lambda_5738939ec88434c53e1a446c47cf2db6>@@QBEP6IXXZXZ
00000000 t ??R<lambda_5738939ec88434c53e1a446c47cf2db6>@@QBEXXZ

解决方案

Cast it:

WinApiFunc(static_cast<void(__stdcall *)()>(func));

Or store it into a local variable first:

void (__stdcall *funcp)() = func;
WinApiFunc(funcp);

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