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

View products that this article applies to.

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.

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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.

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RESOLUTION

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

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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 (http://support.microsoft.com/kb/194022/EN-US/ ) INFO: Visual Studio 6.0 Service Packs, What, Where, Why

194295 (http://support.microsoft.com/kb/194295/EN-US/ ) HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed

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MORE INFORMATION

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);

}

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