Using a function of a superclass as template param is not allowed

struct A{
  void f(){}
};

struct B:public A{
};


template<typename C,void (C::*f)()>
struct Call{

  void operator()(C* c){
    (c->*f)();
  }
};


int main(){
  B b;
  Call<B,&B::f> a;
  a(&b);

}

====Compiler output===

 error: could not convert template argument ‘&A::f’ to ‘void (B::*)()’

~~~~~~~INSTEAD~~~~~~

 void (B::*f)()=&B::f; works