Currently there is no standard way of doing this in C++ although the information must be available somewhere. Otherwise, how could the program call the function? However, GCC provides an extension that allows us to retrieve the address of a virtual function:
void (A::*mfp)() = &A::func;
printf("address: %p", (void*)(b->*mfp));
…assuming the member function has the prototype void func().
This can be pretty useful when you want to cache the address of a virtual function or use it in generated code. GCC will warn you about this construct unless you specify -Wno-pmf-conversions. It’s unlikely that it works with any other compiler.