FIX: C2974 Error When Calling Templated Base Class Functions

The information in this article applies to:

• The Microsoft C/C++ Compiler (CL.EXE) included with: Microsoft Visual C++, 32-bit Edition, versions 2.0 and 2.1

SYMPTOMS

Calling a member function of a templated base class through the 'this' pointer produces the following erroneous error:

   error C2974: '<base templated class name>' : invalid template actual
   argument '#1', type expected.

RESOLUTION

Call the function without using the 'this' pointer.

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.

MORE INFORMATION

The Visual C++ compiler generates the following errors when the following sample program (TEST.CPP), is compiled with the /D"SHOW_TEMPLATE_ERROR" option:

test.cpp(20) : error C2974: 'A' : invalid template actual argument '#1',

               type expected

               points to 'class', use '->'

               error(s); stop ping compilation

Sample Code to Demonstrate Problem

/* Compile options needed: none
*/
// #define SHOW_TEMPLATE_ERROR

    Type a;
    void Afunc(void){};

template <class Type1, class Type2> class B: public A<Type1> { public:

    void Bfunc()
    {

        this->A<Type1>::Afunc();

        A<Type1>::Afunc();

    }

void main()

    B<int, int> b;