FIX: Cannot Watch Local Variables of a _

SYMPTOMS

When stepping into the __finally block of a try-finally statement, any variables that might exist local to that block may not show correct values in the locals or watch window of the integrated debugger.

RESOLUTION

If you need to watch variables used in a __finally block of a try-finally statement, either declare the variables outside of the scope of the __finally block, or assign the value of the local variable to another variable of the same type that has been declared outside the scope of the __finally block.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This problem was not reproducible in Microsoft Visual C++, 32-bit Edition, version 4.0.

MORE INFORMATION

The try-finally statement is a Microsoft extension to the C language that enables applications to guarantee execution of cleanup code when execution of a block of code is interrupted.

You can use the sample code listed below to demonstrate the problem described in this article. You will see the value of the variable 'i' is incorrect in the locals or watch window when stepping through the code of the __finally block.

Sample Code to Demonstrate Problem

/* Compile options needed: /Zi
*/ 

#include <stdio.h>

void main( void )
{
   __try
   {

      // guarded section code...
   }
   __finally
   {
      int i = 2;

      // termination handler code...
      i = 10;
      i = 15;
      i++;
      printf( "In __finally.  i = %d.\n", i );
   }
}