Q166719: FIX: Wrong Exception Rethrown with Global Optimization

Article: Q166719
Product(s): Microsoft C Compiler
Version(s): winnt:5.0
Operating System(s): 
Keyword(s): kbcode kbtool kbVC500bug kbVC600fixkbbuglist
Last Modified: 04-MAY-2001

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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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