FIX: Ambiguous C2966 Error with Nested Template Classes

• The compiler included with Microsoft Visual C++, 32-bit Edition, versions 2.0, 2.1, 2.2, 4.0, 4.1, 4.2

SYMPTOMS

An ambiguous C2966 error is generated if any members of a nested template class are defined externally. The sample code shown in the "More Information" section of this article reproduces this problem and gives the following error message:

   error C2966: '<Unknown>' : adding member function of same name as
                existing static data member for template class 'Outer'

RESOLUTION

Define members of a nested template class inline only.

NOTE: external definitions with the inline keyword will still generate the ambiguous C2966 error.

STATUS

Microsoft has confirmed this to be a 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 Reproduce Problem

   // Compile option needed: none

   template<class T> class Outer {
     public:
         class Inner {
         public:
             static T sobj;
             static T smfunc(T arg);
    };

     };

     //Initialize nested class static object

     template <class T> T Outer<T>::Inner::sobj = T();

     // Out-of-line definition of nested class static member function
     // Moving this definition inside class resolves the error
    template <class T> T Outer<T>::Inner::smfunc(T arg)
    {
       return arg + sobj;
    }