Question

I am having trouble getting a class to be friend with a template and all its partial specializations. Is there any specific trick to achieve this or some limitation I am not aware of?

Answer 1

class Y{
  template<class T>
  friend class X; // friends all instantiation forms of X

  void a_private_func() const{}
};

template<class T>
class X{
public:
  void f(Y const& y){ y.a_private_func(); }
};

template<class T>
class X<T*>{
public:
  void g(Y const& y){ y.a_private_func(); }
};

Live example on Ideone.