Pointers to virtual member functions. How does it work?

Question

Consider the following C++ code:

class A
{
public:
      virtual void f()=0;
};


int main()
{
     void (A::*f)()=&A::f;
}

If I\'d hav

Answer 1

It works because the Standard says that's how it should happen. I did some tests with GCC, and it turns out for virtual functions, GCC stores the virtual table offset of the function in question, in bytes.

struct A { virtual void f() { } virtual void g() { } }; 
int main() { 
  union insp { 
    void (A::*pf)();
    ptrdiff_t pd[2]; 
  }; 
  insp p[] = { { &A::f }, { &A::g } }; 
  std::cout << p[0].pd[0] << " "
            << p[1].pd[0] << std::endl;
}

That program outputs 1 5 - the byte offsets of the virtual table entries of those two functions. It follows the Itanium C++ ABI, which specifies that.