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

This article was previously published under Q216720
This article has been archived. It is offered "as is" and will no longer be updated.
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
MORE INFORMATION

Steps to Reproduce Behavior

Compile with /Og
// Workaround: replace the bool& with boolvoid 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);}				
Properties

Article ID: 216720 - Last Review: 02/21/2014 00:33:39 - Revision: 2.0

  • Microsoft Visual C++ 6.0 Enterprise Edition
  • Microsoft Visual C++ 6.0 Professional Edition
  • Microsoft Visual C++, 32-bit Learning Edition 6.0
  • kbnosurvey kbarchive kbbug kbfix kbvc600fix kbvs600sp3fix KB216720
Feedback