Instance of private class before auto

Question

I'm trying to find how to instantiate an element of a private subclass "before auto", so how to make the second line of the main working fine:

class A{
private:
    class B{
    public:
        void f(){};
    };

public:
    static B getB(){ return {};};
};
int main(){
    auto x1 = A::getB();
    A::B x2 = A::getB(); // B is a private member of A , so i can't write A::B
}

Answer 1

It would be quite rare for this to be useful. I would recommend first figuring out why do this rather than how to do it.

There is no way to get A::B to work outside the scope of A given private B. But you can for example provide a public alias in a friend class, and use a similar declaration:

class A{
    // ...
    friend struct C;
};

struct C {
    typedef A::B B;
};

C::B x2 = A::getB();