DOCUMENT:Q148255  03-AUG-2001  [visualc]
TITLE   :FIX: C1001 on Cast to Base from Derived Friend Class
PRODUCT :Microsoft C Compiler
PROD/VER::4.0,4.1,4.2
OPER/SYS:
KEYWORDS:kbProgramming kbtool kbCompiler kbCPPonly kbVC

======================================================================
-------------------------------------------------------------------------------
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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