Break C++ encapsulation

break_cpp_encapsulation.cpp

class A {
    template<class T> class B {};
    template<class T> friend class C;
    int priv;
protected:
    int pro;
};

template<typename T, typename U>
class Access : public T {
protected:
    static U& access(T& o) { return static_cast<U&>(o); }
};

class D : public Access<A, D> {
    static int toto() {
        A a;
        D &b = static_cast<D&>(a);
        return b.pro + access(a).pro;
    }
    int tata() {
        A a;
        return access(a).pro;
    }
};

template<class T> class C {
};

namespace {
    struct X__20 {};
}

template<> class A::B<X__20> {
    static int toto() {
        A a;
        return a.priv;
    }
};

template<> class C<X__20> {
    static int toto() {
        A a;
        return a.priv;
    }
};