C++ compilation Error C2371 'WCHAR': redefinition; different basic types

Question

C++ compilation Error C2371 'WCHAR': redefinition; different basic types

Shreekant Jadon 1

Hello All,

We are facing the below error in C++ code compilation which is basically a windows file "odbcss.h" we dont think we should change this file.
could you please check this and let us know how to fix this issue that will be great help?

code spinet

    #ifdef UNICODE
    typedef wchar_t DBCHAR;
    #else
   typedef char            DBCHAR; //line 438
    #endif

error: Error C2371 'WCHAR': redefinition; different basic types
file : c:\program files (x86)\windows kits\10\include\10.0.19041.0\um\odbcss.h line : 438

we have gone through the below link for similar kind of issue but there few suggestion but no solution worked to fix the issue.
https://social.msdn.microsoft.com/Forums/vstudio/en-US/078fdbf0-7e61-4654-8ece-837fb5a74e2e/wchar-redefinition-in-odbcssh?forum=vcgeneral

Thanks,
Shreekant

Guido Franzke 2,191 Reputation points

2021-11-08T11:34:08.58+00:00

It's not an error in the standard include file. You are using include files that define the type again. You show odbcss.h, which is the other header file? What kind of project do you use when including odbcss.h?
Check your include files and preprocessor defines.
RLWA32 49,541 Reputation points

2021-11-08T11:39:30.377+00:00

Error was not reproduced with VS2019 and 19041 SDK.

Minimal code -

Unicode Build results -
Viorel 122.6K Reputation points

2021-11-08T12:33:54.183+00:00

Is it possible to use the "Use Unicode Character Set" value for your Project Configuration, Character Set parameter?
Shreekant Jadon 1 Reputation point

2021-11-29T13:46:15.48+00:00

yes, did change the config settings but did not help, thank you, any more suggestions please?
Shreekant Jadon 1 Reputation point

2021-11-29T13:47:09.107+00:00

I am using VS2017 and error is still there, any more suggestions please?
Shreekant Jadon 1 Reputation point

2021-11-29T13:58:14.45+00:00

thanks for your response GuidoFranzke ·
we are not using any additionally header files in odbcs.h, its a windows file and we didn't modify it. the only header I can see in it is "#include <winapifamily.h>"
We are using this file in a C++ project that has some business logic in it. Any more help would be apreciated.

Thanks,
Shreekant
RLWA32 49,541 Reputation points

2021-11-29T14:32:20.663+00:00

I doubt whether VS2019 versus VS2017 made a difference. The quick test with VS2019 used the 19041 SDK which is the same version of the Windows 10 SDK that your code appears to be using.

Can you share a minimal sample that reproduces the issue?
Viorel 122.6K Reputation points

2021-11-29T14:45:38.007+00:00

Maybe you did not change it for the required Configuration and Platform, such as "Debug", "x86".

Shreekant Jadon 1

the code is already there in question, check below as well and I am using windows 10 SDK

//  Internal server datatypes - used when binding to SQL_C_BINARY
#ifndef MAXNUMERICLEN   // Resolve ODS/DBLib conflicts
// DB-Library datatypes
#define DBMAXCHAR       (8000+1)    // Max length of DBVARBINARY and DBVARCHAR, etc. +1 for zero byte
#define MAXNAME         (SQL_MAX_SQLSERVERNAME+1)   // Max server identifier length including zero byte

#ifdef UNICODE
typedef wchar_t         DBCHAR;
#else
typedef char            DBCHAR;  //Error line
#endif
typedef unsigned char   DBBINARY;
typedef unsigned char   DBTINYINT;
typedef short           DBSMALLINT;
typedef unsigned short  DBUSMALLINT;
typedef double          DBFLT8;
typedef unsigned char   DBBIT;
typedef unsigned char   DBBOOL;
typedef float           DBFLT4;

Guido Franzke 2,191 Reputation points

2021-11-30T06:57:44.183+00:00

You only show the code of the standard include file. This is not helpful. Show us your code where you include the header file. We only need to see your include directives so that we can try to reproduce your problem.
Guido Franzke 2,191 Reputation points

2021-11-30T06:59:59.207+00:00

Of course you do not change the standard odbcs.h file. You must show us all the includes in your code. Showing code of the standard files does not help us because it works. You must include another include file somewhere else in your code.
Shreekant Jadon 1 Reputation point

2021-12-16T13:19:43.467+00:00

Thanks for all the help.

Here is the list of includes in different files separated by dots (...)

include "nrxsqllibPCH.h"

include "ODBCSS.H"

include <nrxapplication/NLog.h>

...

include "odbcinst.h"

include "ODBCConfig.h"

include "Odbcss.h"

include "Sql.h"

include "Sqlext.h"

include "Sqltypes.h"

...

include <afxmt.h>

include <thr/Guard.h>

include <sql.h>

include <sqlext.h>

include <odbcss.h>

...

include <windows.h>

include <Sql.h>

include <Sqlext.h>

include <Sqltypes.h>

include <ODBCSS.h>

I tried below as well but did not help

Make sure windows.h or afxwin.h( if its MFC app) is included before this include. Ideal sequence would be.

include <afxcmn.h> //if MFC

include <sql.h>

include <odbcss.h>

or

include <windows.h>

include <sql.h>

include <odbcss.h>

Your answer

Guido Franzke 2,191 Reputation points

2021-11-08T11:34:08.58+00:00

It's not an error in the standard include file. You are using include files that define the type again. You show odbcss.h, which is the other header file? What kind of project do you use when including odbcss.h?
Check your include files and preprocessor defines.
RLWA32 49,541 Reputation points

2021-11-08T11:39:30.377+00:00

Error was not reproduced with VS2019 and 19041 SDK.

Minimal code -

Unicode Build results -
Viorel 122.6K Reputation points

2021-11-08T12:33:54.183+00:00

Is it possible to use the "Use Unicode Character Set" value for your Project Configuration, Character Set parameter?
Shreekant Jadon 1 Reputation point

2021-11-29T13:46:15.48+00:00

yes, did change the config settings but did not help, thank you, any more suggestions please?
Shreekant Jadon 1 Reputation point

2021-11-29T13:47:09.107+00:00

I am using VS2017 and error is still there, any more suggestions please?
Shreekant Jadon 1 Reputation point

2021-11-29T13:58:14.45+00:00

thanks for your response GuidoFranzke ·
we are not using any additionally header files in odbcs.h, its a windows file and we didn't modify it. the only header I can see in it is "#include <winapifamily.h>"
We are using this file in a C++ project that has some business logic in it. Any more help would be apreciated.

Thanks,
Shreekant
RLWA32 49,541 Reputation points

2021-11-29T14:32:20.663+00:00

I doubt whether VS2019 versus VS2017 made a difference. The quick test with VS2019 used the 19041 SDK which is the same version of the Windows 10 SDK that your code appears to be using.

Can you share a minimal sample that reproduces the issue?
Viorel 122.6K Reputation points

2021-11-29T14:45:38.007+00:00

Maybe you did not change it for the required Configuration and Platform, such as "Debug", "x86".
Shreekant Jadon 1 Reputation point

2021-11-29T15:35:02.137+00:00

the code is already there in question, check below as well and I am using windows 10 SDK

// Internal server datatypes - used when binding to SQL_C_BINARY #ifndef MAXNUMERICLEN // Resolve ODS/DBLib conflicts // DB-Library datatypes #define DBMAXCHAR (8000+1) // Max length of DBVARBINARY and DBVARCHAR, etc. +1 for zero byte #define MAXNAME (SQL_MAX_SQLSERVERNAME+1) // Max server identifier length including zero byte #ifdef UNICODE typedef wchar_t DBCHAR; #else typedef char DBCHAR; //Error line #endif typedef unsigned char DBBINARY; typedef unsigned char DBTINYINT; typedef short DBSMALLINT; typedef unsigned short DBUSMALLINT; typedef double DBFLT8; typedef unsigned char DBBIT; typedef unsigned char DBBOOL; typedef float DBFLT4;
Guido Franzke 2,191 Reputation points

2021-11-30T06:57:44.183+00:00

You only show the code of the standard include file. This is not helpful. Show us your code where you include the header file. We only need to see your include directives so that we can try to reproduce your problem.
Guido Franzke 2,191 Reputation points

2021-11-30T06:59:59.207+00:00

Of course you do not change the standard odbcs.h file. You must show us all the includes in your code. Showing code of the standard files does not help us because it works. You must include another include file somewhere else in your code.
Shreekant Jadon 1 Reputation point

2021-12-16T13:19:43.467+00:00

Thanks for all the help.

Here is the list of includes in different files separated by dots (...)

include "nrxsqllibPCH.h"

include "ODBCSS.H"

include <nrxapplication/NLog.h>

...

include "odbcinst.h"

include "ODBCConfig.h"

include "Odbcss.h"

include "Sql.h"

include "Sqlext.h"

include "Sqltypes.h"

...

include <afxmt.h>

include <thr/Guard.h>

include <sql.h>

include <sqlext.h>

include <odbcss.h>

...

include <windows.h>

include <Sql.h>

include <Sqlext.h>

include <Sqltypes.h>

include <ODBCSS.h>

I tried below as well but did not help

Make sure windows.h or afxwin.h( if its MFC app) is included before this include. Ideal sequence would be.

include <afxcmn.h> //if MFC

include <sql.h>

include <odbcss.h>

or

include <windows.h>

include <sql.h>

include <odbcss.h>

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C++ compilation Error C2371 'WCHAR': redefinition; different basic types

code spinet

include "nrxsqllibPCH.h"

include "ODBCSS.H"

include <nrxapplication/NLog.h>

include "odbcinst.h"

include "ODBCConfig.h"

include "Odbcss.h"

include "Sql.h"

include "Sqlext.h"

include "Sqltypes.h"

include <afxmt.h>

include <thr/Guard.h>

include <sql.h>

include <sqlext.h>

include <odbcss.h>

include <windows.h>

include <Sql.h>

include <Sqlext.h>

include <Sqltypes.h>

include <ODBCSS.h>

include <afxcmn.h> //if MFC

include <sql.h>

include <odbcss.h>

include <windows.h>

include <sql.h>

include <odbcss.h>

Your answer