Hello!

One problem with friendship is that it is all or nothing.

I think there should exist a kind of limited friendship as follows:

class A;

class B {
private:
        [[limited]] friend class A;
        void x();
private:
        void y();
};

where the [[limited]] attribute on the friend declaration means that A is
granted access to the parts of B within the same "access specifier section"
as the friend declaration.

Now, "access specifier section" is a new term and refer to all declarations
between two access specifiers of an aggregate.

That limited is an attribute is because a simple implementation could ignore
it and the code would still work as intended, it would just grant too much
friendship to A.

/MF