Microsoft KB Archive/131000

= FIX: Application Error If /Og & Virtual Operator Call in Loop =

Article ID: 131000

Article Last Modified on 7/5/2005

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APPLIES TO


 * Microsoft Visual C++ 2.0 Professional Edition
 * Microsoft Visual C++ 2.1

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This article was previously published under Q131000



SYMPTOMS
An application error is generated when running a program that meets all these conditions:


 * It was compiled with global optimization (/Og).
 * It defines a virtual operator for a class.
 * It constructs an object of that class inside a loop.
 * The operator is called inside the loop.



CAUSE
The computation of the address of the virtual operator is being lifted out of the loop.



RESOLUTION
Use any one of the following four workarounds:


 * Move the object outside the loop. -or-


 * Use the functional form of the operator. -or-


 * If the operator does not need to be virtual, do not declare it virtual. -or-


 * Do not do global optimizations.



STATUS
Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This problem was fixed in Microsoft Visual C++, 32-bit Edition, version 4.0.



Sample Code to Reproduce Problem
/* Compile options needed: /Og class Test { public: virtual int operator <= ( const Test& T ) const {return 1;} };

void main( void ) {   long i;    for (i=1; i<=3; i++) {       Test T; //Work-around 1: Move this line above the for loop. T <= T; //Work-around 2: Comment out this line, uncomment the next. //T.operator<=(T); // Function form of the operator. } }

Additional query words: 2.00 2.10 9.0 9.1 9.00 9.10

Keywords: kbbug kbfix kbcodegen kbcpponly kbcompiler KB131000

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