DOCUMENT:Q263609  03-MAY-2001  [visualc]
TITLE   :BUG: Bad Code for Unsigned and Signed Comparisons with /Og
PRODUCT :Microsoft C Compiler
PROD/VER::6.0
OPER/SYS:
KEYWORDS:kbCodeGen kbCompiler kbVC600bug

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The information in this article applies to:

 - The C/C++ Compiler (CL.EXE), included with:
    - Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0 
    - Microsoft Visual C++, 32-bit Professional Edition, version 6.0 
    - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
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SYMPTOMS
========

The compiler may generate incorrect code for a signed comparison following an
unsigned same comparison when the /Og optimization is enabled.

Please refer to the sample code in the "More Information" section for details.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.


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

Steps to Reproduce Behavior
---------------------------

The following sample code demonstrates the bug:

   // Test.cpp
   // Compiler option needed: /Og
   #include <stdio.h>
   int a=-1;
   void main() {
   	if ((unsigned int)a > 5U) {
   		if (a > 5) {
   			printf("%d > 5\n", a);
   		} else {
   			printf("%d < 0\n", a);
   		}
   	} else {
   		printf("0 <= %d <= 5\n", a);
   	}
   }

Program Output:
-1 > 5

Additional query words:

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Keywords          : kbCodeGen kbCompiler kbVC600bug 
Technology        : kbVCsearch kbAudDeveloper kbCVCComp
Version           : :6.0
Issue type        : kbbug

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