BUG: /Za Compiler Option Causes Errors with "==" Operator

The information in this article applies to:

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

      - Microsoft Visual C++ for Windows, versions 1.0 and 1.5
  

SYMPTOMS

The equal to operator ("==") may cause the compiler to generate different errors when the /Za compiler option (Disable Microsoft Extensions) is used.

C/C++ version 8.0 will generate the following DOSXNT error when built with the /Za and /Bd option:

   fatal error DX1020: unhandled exception: General protection fault

   DX2010: invalid pointer passed to free or realloc.

   test.cpp(27) : fatal error C1001: internal compiler error
                  (compiler file 'msc1.cpp', line 585)

RESOLUTION

The example below illustrates the problem with the following statement:

   if( a == test());

STATUS

Microsoft has confirmed this to be a problem with the C/C++ compiler for MS-DOS, versions 8.0 and 8.0c. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

The problem does not occur with the C/C++ 32-bit compiler, version 8.0.

MORE INFORMATION

The sample code below may be used to reproduce this problem. To invoke the /Za option from within the Visual Workbench, choose Project from the Options menu, then choose Compiler. Select the Custom Options category from the Compiler Options dialog box, then check Disable Microsoft Language Extensions. With the sample code, use an MS-DOS Executable as the project target.

Sample Code

/* Compile options needed: /Za
*/

 public:
   int val(void) const {return 1;}

typedef class BB:public B { } BB;

typedef class A { public:

// int operator==(const BB &b) const {return b.val();}
   int operator==(const B &b) const {return b.val();}

BB test(void) {

   BB b;

   return b;

void main(void)

   A a;

   if( a==test() );