Boost::asio winsock and winsock 2 compatibility issue

Question

My project uses windows.h in which winsock.h is used, and I need to include boost:assio which uses winsock2. So I get many errors that says Winsock.h already included. I can define WIN32_LEAN_AND_MEAN. so that windows.h wouldn't use winsock. The problem is , that I need windows.h to use it, and I just need Asio for asynchronous timers. I don't need its winsock2.h . I tried searching how to disable its winsock2 use, and I found that I could do that by defining BOOST_ASIO_NO_WIN32_LEAN_AND_MEAN before including boost:asio, but I still get the same error.

#include <windows.h>
#define BOOST_ASIO_NO_WIN32_LEAN_AND_MEAN
#include <boost/asio.hpp>

Error

1>c:\program files\boost\boost_1_47\boost\asio\detail\socket_types.hpp(22): fatal error C1189: #error : WinSock.h has already been included

Answer 1

Try and change the order of includes. Start with boost/asio.hpp and put windows.h after it.

Usually the writers of any code library solve the compatibility issues but they can do it better if their code is the first to meet the compiler and preprocessor.

There's a similar issue with ACE, including ace/OS.h before anything else solves it.

Answer 2

As Danius (the OP) points out a compile with

#include <windows.h>
#include <boost/asio.hpp>

fails with this error:

1>c:\source\<SNIP>\boost\1.51.0\boost\asio\detail\socket_types.hpp(22): fatal error C1189: #error :  WinSock.h has already been included

On the other hand

#include <boost/asio.hpp>
#include <windows.h>

Produces a bunch of noise and sets the windows version # incorrectly

1?  Please define _WIN32_WINNT or _WIN32_WINDOWS appropriately. For example:
1>  - add -D_WIN32_WINNT=0x0501 to the compiler command line; or
1>  - add _WIN32_WINNT=0x0501 to your project's Preprocessor Definitions.
1>  Assuming _WIN32_WINNT=0x0501 (i.e. Windows XP target).

I couldn't find any way around this that didn't leave a bad taste, but this:

#ifdef _WIN32
#  ifdef USE_ASIO
//     Set the proper SDK version before including boost/Asio
#      include <SDKDDKVer.h>
//     Note boost/ASIO includes Windows.h. 
#      include <boost/asio.hpp>
#   else //  USE_ASIO
#      include <Windows.h>
#   endif //  USE_ASIO
#else // _WIN32
#  ifdef USE_ASIO
#     include <boost/asio.hpp>
#  endif // USE_ASIO
#endif //_WIN32

Does produce a clean compile.

<EDITORIAL> It shouldn't be that hard </EDITORIAL>