Knowledge Base

BUG: Incorrect Evaluation of Static Member Functions in Debugger

Article ID: 168380

Article Last Modified on 12/8/2003

The Integrated Debugger, when used with:
- Microsoft Visual C++ 4.0 Standard Edition
- Microsoft Visual C++ 4.1 Subscription
- Microsoft Visual C++ 4.2 Enterprise Edition
- Microsoft Visual C++ 4.2 Professional Edition
- Microsoft Visual C++ 5.0 Enterprise Edition
- Microsoft Visual C++ 5.0 Professional Edition
- Microsoft Visual C++ 6.0 Enterprise Edition
- Microsoft Visual C++ 6.0 Professional Edition
- Microsoft Visual C++ 6.0 Standard Edition

This article was previously published under Q168380

SYMPTOMS

Function evaluation of static member functions cannot be done in the Watch or the QuickWatch window of the debugger. You a wrong value, or get the following error message:

Error:cannot display value

CAUSE

The expression evaluator in the debugger does not properly distinguish between static and non-static methods. The first case listed above appears to be an evaluation of a method without a "this" pointer, hence, we get an "Error:cannot display value" message. The second case occurs because the debugger is not properly distinguishing between static and non-static member functions. The "this" pointer is pushed onto the stack to evaluate the static member function, which is incorrect.

RESOLUTION

There is no workaround. Do not attempt to evaluate static member functions from within the debugger, either in the watch or quick watch window.

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

Use the following sample code and build it with debug information:

    class A
    {
      public:
      static int bar (int i) {return i;}
    };

    void main ()
    {
      A  f;
      int j = A::bar(200);
      int i = f.bar(100);
    }

Start the debugger by stepping into (F11 key) function "main." In the Watch or QuickWatch window, type A::bar(200) and you will get the error message described in the SYMPTOMS section. Typing f.bar(100) produces a wrong value.

Keywords: kbbug kbide kbdebug KB168380