BUG: Member Function Referenced Without () Compiles

• Microsoft Visual C++, 32-bit Edition, versions 4.0, 4.1, 4.2, 5.0

SYMPTOMS

Leaving the parentheses off a member function call, or leaving the ampersand “&” off a reference to a pointer to a member function, does not result in a compiler error.

CAUSE

In both cases, the Visual C++ compiler is incorrectly treating the reference as a pointer to the member function. A pointer to a member function cannot be referenced via a specific instance of a class (for example, "obj.MyFunct" in the sample code below). Instead, it must be referenced via the class name, scope operator and '&' operator (for example, &CMyClass::MyFunc in the sample code below).

RESOLUTION

The compiler should report an error on the line in question.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this bug and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

Sample Code

   /* Compile options needed:
   */


   class CMyClass
   {

     public:

     void MyFunc() {int nVar = 100; }
   };


   void main()
   {
     CMyClass obj;

     obj.MyFunc();  //Correct syntax - calls the member function
     obj.MyFunc;    //Typo, no (), should result in error but doesn't
                    //VC 5.0: correct warning C4551
     CMyClass::MyFunc;  // Typo, no &, should result in error but doesn't
     &CMyClass::MyFunc; // Correctly treated as a pointer to member
                        // function.
   }

Also note that this problem could seem to cause incorrect execution paths if the parenthesis are left off accidentally in the following type of construct:

   if (obj.MyFunc) {   // Should be an error, instead always evaluates to
                       // TRUE. This code always executes.
   }
   else {
       // This code will never be reached.
   }

Keywords          : CLIss CodeGen CPPIss vcbuglist400 vcbuglist410 vcbuglist420 vcbuglist500
Version           : 4.0 4.1 4.2 5.0
Platform          : NT WINDOWS
Issue type        : kbbug