class A
{
public:
  virtual A* f() { return this;};
  A* get_this() { return this;};
};

template<typename B>
class C : public A
{
public:
  virtual B f() { return (B)A::get_this();};
};

class D : public A {
  int x;
public:
};

template<>
class C<D*> : public A
{
public:
  virtual D* C<D*>::f() { return (D*)0;};
};

int main( ) {
  C<A*> CA;
  C<D*> DA;

  return 0;
}