DOCUMENT:Q172887  06-MAY-2001  [visualc]
TITLE   :FIX: Debugger Cannot Safely Change Current Location
PRODUCT :Microsoft C Compiler
PROD/VER:winnt:5.0
OPER/SYS:
KEYWORDS:kbDebug kbide kbVC500bug kbVC600fix

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - The Integrated Debugger, included with:
    - Microsoft Visual C++, 32-bit Professional Edition, version 5.0, used with:
       - the hardware: DEC Alpha 
-------------------------------------------------------------------------------

SYMPTOMS
========

The debugger cannot safely change the current location of a stopped program (for
example, using the Set-Next-Statement function) from inside a catch handler to
the body of the program.

CAUSE
=====

This problem is related to the difference between Intel and Alpha exception
handling. The catch handler on the Alpha architecture is effectively a separate
function that allows clean handling of exceptions that are raised within the
exception handler. Any change of the current location from the handler to the
body of the program would bypass the handler epilogue and result in incorrect
values in the registers, and an incorrect stack frame.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This problem was corrected in Visual C++ version 6.0
for Windows.

Additional query words: IP instruction

======================================================================
Keywords          : kbDebug kbide kbVC500bug kbVC600fix 
Technology        : kbVCsearch kbAudDeveloper kbIntegratedDebugger
Version           : winnt:5.0
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2001.