Q121887: PRB: Debugger Can’t Evaluate Cast of Enum to (long*)

Article: Q121887
Product(s): Microsoft C Compiler
Version(s): 2.0,2.1,4.0,5.0,6.0
Operating System(s): 
Keyword(s): kbDebug kbide kbVC200 kbVC210 kbVC400 kbVC500 kbVC600
Last Modified: 14-FEB-2002

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The information in this article applies to:

- The Visual Workbench Integrated Debugger, used with:
   - Microsoft Visual C++, 32-bit Enterprise Edition, versions 5.0, 6.0 
   - Microsoft Visual C++, 32-bit Professional Edition, versions 5.0, 6.0 
   - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
   - Microsoft Visual C++, Macintosh Cross-Development Addon, version 2.0 
   - Microsoft Visual C++, 32-bit Editions, versions 2.0, 2.1, 4.0, 6.0, used with:
      - the hardware: Intel x86 
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SYMPTOMS
========

The Visual Workbench Debugger expression evaluator cannot evaluate the cast of
an enumerator to a pointer to a long in C++ code. If you attempt to enter an
expression of this type in the debugger's watch window, an error occurs. For
example, if you try to watch the enumerator 'a' as shown in the sample code
below, the debugger gives this error:

  (long*)a = CXX0019: Error: bad type cast

The error occurs even though the cast is legal.

RESOLUTION
==========

If the enumerator is assigned to a pointer to a long at compile time, the
debugger can watch the pointer (see the Sample Code section below).

STATUS
======

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

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

The following sample code demonstrates the problem. Entering (long*)a in the
Watch window causes error CXX0019.

Sample Code
-----------

  /* Compile options needed: /Zi /Od test.cpp
  */ 

  enum {a=1, b=2, c=3};

  void main()
  {
     long *ptr;
     ptr = (long*)a;  // Cast works correctly in code.
  }

Additional query words:

======================================================================
Keywords          : kbDebug kbide kbVC200 kbVC210 kbVC400 kbVC500 kbVC600 
Technology        : kbVCsearch kbAudDeveloper
Version           : :2.0,2.1,4.0,5.0,6.0
Issue type        : kbprb

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