SOCKET in winsock2.h not accepted in visual studio 2017

Question

Getting error i freetds headers when i include them in my VS 2017 c++ project

in tds.h when i include that in my project

    include\tds.h(1331): error C3646: 's': unknown override specifier
    include\tds.h(1331): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
    include\tds.h(1641): error C2065: 'TDS_SYS_SOCKET': undeclared identifier
    include\tds.h(1641): error C2146: syntax error: missing ')' before identifier 's'

I am trying to use freetds 0.91.100 version in my c++ application which was built using VS 2010. It was fine then.

Now after migrating my C++ project to VS 2017 i am getting strange errors. I have built freetds lib as well in VS 2017.

freetds has this declaration in tds_sysdep_private.h

#if !defined(__WIN32__) && !defined(_WIN32) && !defined(WIN32)
typedef int TDS_SYS_SOCKET;
#define INVALID_SOCKET -1
#define TDS_IS_SOCKET_INVALID(s) ((s) < 0)
#else
typedef SOCKET TDS_SYS_SOCKET;
#define TDS_IS_SOCKET_INVALID(s) ((s) == INVALID_SOCKET)
#endif

and the tds.h has

struct tds_socket
{
TDS_SYS_SOCKET s;       /**< tcp socket, INVALID_SOCKET if not connected */
}

And the error is on this TDS_SYS_SOCKET declaration

My code include this header this way.

tdsloader.h

using namespace std;
#if defined (__cplusplus)
extern "C" {
#endif
#include "tds.h"
#if defined (__cplusplus)
}
#endif

As per the declaration of TDS_SYS_SOCKET in tds_sysdep_private.h , in case of windows build it is defined as SOCKET which is from winsock2.h

I read in other threads that the order of header file includion is important and i made sure that winsock2.h is included before windows.h or any other windows header file.

Now that SOCKET from winsock2.h is typedef UINT_PTR SOCKET;

which in an unsigned , why is VS 2017 not able to recognize the type ?

Build should go through smoothly as it did in VS 2010.

Now with VS 2017 it shows build errors.

can some one tell me the reason for negative rating as well ? — Deepak Selvakumar, Feb 12 '19 at 09:40
Probably because you didn't provide an MCVE. https://stackoverflow.com/help/mcve — Blaze, Feb 12 '19 at 10:30
@DeepakSelvakumar Did you include tds_sysdep_private.h before including tds.h? — Marcin Zawiejski, Feb 12 '19 at 10:30
@MarcinZawiejski tds.h internally includes tds_sysdep_private.h before anything else. All these were getting built properly in VS 2010. I dont understand what is the difference now. — Deepak Selvakumar, Feb 12 '19 at 10:52
@DeepakSelvakumar Unfortunately can't help you without a MCVE because it works fine for me as per the answer below. — Marcin Zawiejski, Feb 12 '19 at 10:55

Marcin Zawiejski · Answer 1 · 2019-02-12T11:28:09.567

0

Here's the include order that works fine with VS 2017:

#include <tds_sysdep_private.h>
#include <tds.h>

alternatively you can:

#define _FREETDS_LIBRARY_SOURCE
#include <tds.h>

edited Feb 12 '19 at 11:28

answered Feb 12 '19 at 10:32

Marcin Zawiejski

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this order should be followed in the cpp where we use tds ? you have not modified anything inside the freetds lib header files ? what version of freetds are you using ? – Deepak Selvakumar Feb 12 '19 at 11:14
It's for freetds version 0.91.100, no changes to the header files. In fact you don't need to include WinSock2.h and Windows.h because tds_sysdep_private.h already includes them. – Marcin Zawiejski Feb 12 '19 at 11:27
i am using the same version 0.91.100. Yes, tds_sysdep_private.h includes winsoc2.h and windows.h. and tds.h includes tds_sysdep_private.h. Hence, it is okay to only include tds.h, Correct ? as you have mentioned in the second option. – Deepak Selvakumar Feb 12 '19 at 13:23
Yes, it seems correct to include only tds.h but you have to #define _FREETDS_LIBRARY_SOURCE as this causes tds.h to include tds_sysdep_private.h. – Marcin Zawiejski Feb 12 '19 at 17:48

SOCKET in winsock2.h not accepted in visual studio 2017

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