class G<T> {
    x: G<G<T>>; // infinitely expanding type reference
}

class Foo<T extends G<T>> { // error, constraint referencing itself
    bar: T;
}

class D<T> {
    x: G<G<T>>; 
}

var c1 = new Foo<D<string>>(); // ok, circularity in assignment compat check causes success