Microsoft KB Archive/216720

= FIX: Bitwise OR for Bool& Types Causes Error When Optimized =

Article ID: 216720

Article Last Modified on 11/18/2003

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APPLIES TO


 * Microsoft Visual C++ 6.0 Enterprise Edition
 * Microsoft Visual C++ 6.0 Professional Edition
 * Microsoft Visual C++ 6.0 Standard Edition

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This article was previously published under Q216720



SYMPTOMS
When using a bitwise OR operation on a bool reference and compiling with optimizations that include /Og (global optimizations), the resulting executable may generate an access violation.



CAUSE
The current implementation of a bool is an 8-bit value. The OR operation with /Og on a bool reference operates on a 32-bit value.



RESOLUTION
Do not use bitwise operators with bool references. Use bool values instead.



STATUS
Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

This bug was corrected in Visual Studio 6.0 Service Pack 3. For more information about Visual Studio service packs, please see the following articles in the Microsoft Knowledge Base:

194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed



Steps to Reproduce Behavior
Compile with /Og

// Workaround: replace the bool& with bool void func(bool& boolref, float a, float b) { boolref |= (a == b); }

void main {   bool b1 = true;

float f1 = 2.0; float f2 = 2.0;

func(b1,f1,f2);

}

Keywords: kbbug kbfix kbvc600fix kbvs600sp3fix KB216720

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