/WX Option Causes Suppression of C4101 & C4102 Warnings

The information in this article applies to:

• The Microsoft C/C++ Compiler (CL.EXE), included with:

      - Microsoft C/C++ for MS-DOS, versions 7.0
      - Microsoft Visual C++ for Windows, versions 1.0, 1.5, and 1.51
  

SUMMARY

The /WX switch causes the following two warnings

   warning C4102: identifier : unreferenced label
   warning C4101: identifier' : unreferenced local variable

MORE INFORMATION

Normally, the compiler continues to generate errors until the end of compilation or until a fatal error occurs. Because the /WX switch causes warnings to be treated as nonfatal errors, one might expect to see all other occurrences of the C4101 and C4102 warnings. This is not the case.

NOTE: This behavior does not occur using Visual C++ 32-bit Edition.

With the following sample code, if the following command line is used

   cl /W4 /WX file.c

   warning C4035: 'main' : no return value
   error C2220: warning treated as error - no object file generated

   warning C4035: 'main' : no return value
   warning C4102: 'Label' : unreferenced label
   warning C4101: 'b' : unreferenced local variable
   warning C4101: 'c' : unreferenced local variable

Sample Code

In the sample code below, note that by removing the /WX switch, the compiler issues all the warnings.

/* Compile options needed: /W4 /WX
*/

#include <stdio.h>

   int a = 1;
   int b ;
   int c ;

   printf (" a =  %d \n");