BUG: Compiler Omits C4758 and/or C4762 Warnings

The information in this article applies to:

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

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

SYMPTOMS

When you pass the address of a local variable as an argument in a function call and use the /Aw compiler switch, the C/C++ compiler generates different warnings, depending on whether the optimizing compiler is used. There should be warnings generated, but they should be the same each time.

Under C/C++, version 7.0, if the optimizing compiler is used (compile with /f-), the following warning is generated for a .C file:

  test.c(8) : warning C4762: near/far mismatch in argument :
              conversion supplied

  test.c(8) : warning C4758: address of automatic (local) variable
              taken, DS != SS

RESOLUTION

Microsoft has confirmed this to be a bug in the products listed above. We are researching this problem and will post new information in the Microsoft Knowledge Base as soon as it becomes available.

MORE INFORMATION

The following sample can be used to demonstrate the problem. If the file is named TEST.C, warning C4762 is produced. If the file is named TEST.CPP, no warnings are produced.

Sample Code

/* Compile options needed: /ASw /c /f-
*/

void func( char * );

void test( void )

    char sz[32];

    func( sz );