Compiler Error C3772

"name" : invalid friend template declaration

Remarks

It is invalid to declare a friend of a class template specialization. You cannot declare an explicit or partial specialization of a class template and in the same statement declare a friend of that specialization. The name placeholder identifies the invalid declaration.

To correct this error

• Do not declare a friend of a class template specialization.

• If appropriate for your application, declare a friend of the class template, or declare a friend of a particular partial or explicit specialization.

Example

The following code example fails because it declares a friend of a partial specialization of a class template.

// c3772.cpp
// compile with: /c

// A class template.
    template<class T> class A {};

// A partial specialization of the class template.
    template<class T> class A<T*> {};

// An explicit specialization.
    template<> class A<char>;

class X {
// Invalid declaration of a friend of a partial specialization.
    template<class T> friend class A<T*>; // C3772

// Instead, if it is appropriate for your application, declare a
// friend of the class template. Consequently, all specializations
// of the class template are friends:
//    template<class T> friend class A;
// Or declare a friend of a particular partial specialization:
//    friend class A<int*>;
// Or declare a friend of a particular explicit specialization:
//    friend class A<char>;
};

See also

Templates
Template Specialization