May pointer to members circumvent the access level of a member?

Question

Our infamous litb has an interesting article on how to circumvent the access check.

It is fully demonstrated by this simple code:

#include 

        

Answer 1

The code is clearly illegal (and requires a compile time diagnostic). In the line:

template struct Rob;

the expression A::a accesses a private member of A.

The standard is very clear about this: “Access control is applied uniformly to all names, whether the names are referred to from declarations or expressions.“ (§11/4, emphasis added). Since a is a private name in A, any reference to it outside of A is illegal.