type t {
    int x;
}

type t2 <: t {
    int y;
}

type contains_t {
    t x(t2);
}

class c() : t2 impl t2 {
    init int x;
    init int y;

    export t2 : x, y;
}

class cct() : contains_t impl contains_t {
    t2 x(t x) {
        return new c : t2 (x = x.x, y = x.x);
    }
    
    export contains_t : x;
}