DOCUMENT:Q166719  04-MAY-2001  [visualc]
TITLE   :FIX: Wrong Exception Rethrown with Global Optimization
PRODUCT :Microsoft C Compiler
PROD/VER:winnt:5.0
OPER/SYS:
KEYWORDS:kbcode kbtool kbVC500bug kbVC600fixkbbuglist

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

 - The C/C++ Compiler (CL.EXE), used with:
    - Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0 
    - Microsoft Visual C++, 32-bit Professional Edition, version 5.0 
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SYMPTOMS
========

The wrong exception is rethrown when global optimization (/Og) is enabled. For
example, in the following sample, the correct output is:

   A 1st throw
   B 2nd throw
   C 1st throw

However, if global optimization (/Og) is enabled, the output is:

   A 1st throw
   B 2nd throw
   C 2nd throw

RESOLUTION
==========

To work around the problem, disable the global optimization on the command line
or use the optimize pragma to disable the optimization for the function where
the problem occurs. For example:

       #pragma optimize("g", off)

STATUS
======

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

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

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

       //test.cpp
       /* Compiler options needed : /GX  */ 
       #include <iostream>
       using namespace std;
       #pragma optimize("g", on)
       void main() {
           try
           {
               char* pStr = NULL;
               try
               {
                   throw "1st throw\n";
               }
               catch( char* str )
               {
                   cout << "A " << str;
                   try
                   {
                       throw "2nd throw\n";
                   }
                   catch( char* str )
                   {
                       cout <<"B "<< str;
                   }
                   throw;
               }
           }
           catch ( char* str )
           {
               cout <<"C "<< str;
           }
       }

Additional query words:

======================================================================
Keywords          : kbcode kbtool kbVC500bug kbVC600fix kbbuglist
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : winnt:5.0
Issue type        : kbbug
Solution Type     : kbfix

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

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Copyright Microsoft Corporation 2001.