FIX: C2668 in Overloaded Function When enum Is Promoted to int

• The Microsoft C/C++ Compiler (CL.EXE) included with: - Microsoft Visual C++ for Windows, versions 1.5, 1.51, 1.52 - Microsoft Visual C++, 32-bit Edition, versions 2.0, 2.1, 2.2, 4.0,

       4.1, 4.2
  

SYMPTOMS

When a function is overloaded to take an int parameter in one instance and an unsigned int in another, the following error results if a call to the function is made with an enumerated type:

   C2668 error: 'func' : ambiguous call to overloaded function (new
   behavior; please see help)

RESOLUTION

• Use a cast when calling the function, such as func((unsigned)y).

  -or-

• Overload the function to take the enumerated type, such as:

  func(enum A); func(enum E);

STATUS

Microsoft has confirmed this to be bug in the Microsoft products listed at the beginning of this article. This bug was corrected in Visual C++ version 5.0.

MORE INFORMATION

Sample Code to Demonstrate Problem

   // Compile option needed: none

   enum A{eA = 0, eB};
   enum E{e = -1};

   void func(int a);
   void func(unsigned int a);

   void main(){
              A y = eA;
              E e1 = e;
              int m = 2;

              func(m);        // calls func(int)
              func(y);        // C2668 error
              func(e1);       // C2668 error
            }

Keywords          : CPPIss vcbuglist400 vcfixlist500 kbprg
Version           : 1.5 1.51 1.52 2.0 2.1 2.2 4.0 4.
Platform          : NT WINDOWS
Issue type        : kbbug
Solution Type     : kbfix