PR# 19508 C compilation errors due to include in eif_time.h

In the file eif_time.h we can read:

~~~~~~~~~~~
#ifdef EIF_WINDOWS
/* This will include the definition of struct timeval. The implementation of gettimeofday is in class C_DATE. */
#include <windows.h>
#include <winsock2.h>
~~~~~~~~~~~

But this might cause some compilation errors with Windows SDK 10.0.17134 which comes with VisualStudio 2017:

~~~~~~~~~~~
C:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\shared\ws2def.h(235): error C2011: 'sockaddr': 'struct' type redefinition
C:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\um\winsock.h(482): note: see declaration of 'sockaddr'
C:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\shared\ws2def.h(437): error C2059: syntax error: 'constant'
C:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\shared\ws2def.h(633): error C2011: 'sockaddr_in': 'struct' type redefinition
C:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\um\winsock.h(309): note: see declaration of 'sockaddr_in'
C:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\um\winsock2.h(136):error C2011: 'fd_set': 'struct' type redefinition
C:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\um\winsock.h(65): note: see declaration of 'fd_set'
C:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\um\winsock2.h(180): error C2011: 'timeval': 'struct' type redefinition
C:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\um\winsock.h(108): note: see declaration of 'timeval'
C:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\um\winsock2.h(236): error C2011: 'hostent': 'struct' type redefinition
C:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\um\winsock.h(164): note: see declaration of 'hostent'
C:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\um\winsock2.h(249): error C2011: 'netent': 'struct' type redefinition
C:\Program Files (x86)\Windows Kits\10\include\10.0.17134.0\um\winsock.h(177): n ote: see declaration of 'netent'
.... Many more lines deleted .....
~~~~~~~~~~~

On the page: https://docs.microsoft.com/en-us/windows/desktop/api/winsock/ns-winsock-timeval

I can read:

~~~~~~~~~~
Requirements
  	 
Minimum supported client 	Windows 2000 Professional [desktop apps only]
Minimum supported server 	Windows 2000 Server [desktop apps only]
Header 	winsock.h (include Winsock2.h)
~~~~~~~~~~

I tried to replace:

#include <winsock2.h>

by:

#include <winsock.h>

in the file eif_time.h, and then the C code compiled with no error anymore.

--
Eric Bezault

Note that the issue I had was with the EiffelTime, not EiffelStudio. And as a matter of fact I was not using EiffelStudio but another Eiffel compiler to compile this project with EiffelTime. 

I can confirm that adding the C flag -DWIN32_LEAN_AND_MEAN solves the problem.

That being said, it would be nice to explain in the file eif_time.h itself why winsock2.h is used instead of winsock.h as suggested by Microsoft documentation.

--
Eric Bezault

We include `winsock2.h` for compatibility with third party C libraries (zeromq and openssl to name a few). It works with all the versions of C compilers we have. Do you have a case where it does not compile? Note that we now compile with the `-DWIN32_LEAN_AND_MEAN` on Windows to avoid further issues.

It's also in file winsock.h for Windows SDK 8.1 and Windows SDK 10.0.10586 (that's all I have installed on my computer).

--
Eric Bezault

I confirm that this definition:

~~~~~~~~~~~~~~~~~~~~~
/*
 * Structure used in select() call, taken from the BSD file sys/time.h.
 */
struct timeval {
        long    tv_sec;         /* seconds */
        long    tv_usec;        /* and microseconds */
};
~~~~~~~~~~~~~~~~~~~~~

is part of winsock.h in my version of Windows SDK.

--
Eric Bezault