Sometimes, C++'s notion of privacy just baffles me :-)

class Foo
{
    struct Bar;
    Bar* p;

public:

    Bar* operator->() const
    {
        return p;
    }
};

struct Foo::Bar
{
    void baz()
    {
        std::cout << "inside baz\n";
    }
};

int main()
{
    Foo::Bar b;   // error: 'struct Foo::Bar' is private within this context

    Foo f;
    f->baz();     // fine
}

Since Foo::Bar is private, I cannot declare b in main. Yet I can call methods from Foo::Bar just fine. Why the hell is this allowed? Was that an accident or by design?