Q148255: FIX: C1001 on Cast to Base from Derived Friend Class

Article: Q148255
Product(s): Microsoft C Compiler
Version(s): 4.0,4.1,4.2
Operating System(s): 
Keyword(s): kbProgramming kbtool kbCompiler kbCPPonly kbVC
Last Modified: 03-AUG-2001

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The information in this article applies to:

- Microsoft C/C++ Compiler (CL.EXE), included with:
   - *EDITOR Please do not choose this product*Microsoft Visual C++ 32-bit Edition* use 241, 265, 225, versions 4.0, 4.1, 4.2 
-------------------------------------------------------------------------------

SYMPTOMS
========

When an argument in a function call is passed by value and is cast to a base
class from a derived class that is also a friend of the base class, the compiler
generates this error:

  fatal error C1001: INTERNAL COMPILER ERROR
  (compiler file '\school.tp3\test\c10\src\P2\386\codegen.c', line 359)

This occurs only when C++ exception handling is enabled (/GX) and the base class
defines a destructor.

RESOLUTION
==========

There are several workarounds:

- Pass the class by reference.

-or-

- Remove the cast. It is unnecessary.

-or-

- Do not use the /GX compiler option if exception handling isn't required.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This bug was corrected in Visual C++ version 5.0.

MORE INFORMATION
================

Sample Code to Reproduce Problem
--------------------------------

    /* Compile options needed: /GX
     */ 

     class  Cbase {
        friend class Cfriend;
     public:
        ~Cbase( void ) {}
     };

     class Cfriend : public Cbase {};

     void f(Cbase z){}
     //   Workaround 1,pass by reference instead of by value
     //void f(Cbase& z) {}

     void main() {
        Cfriend P;
        // INTERNAL COMPILER ERROR on the following line
        f((Cbase)P);
     //   Workaround 2, do not use a cast.
     //   f(P);
     };

Additional query words: 10.00 10.10 10.20 utilities

======================================================================
Keywords          : kbProgramming kbtool kbCompiler kbCPPonly kbVC 
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : :4.0,4.1,4.2
Issue type        : kbbug
Solution Type     : kbfix

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