1 // CS1961: The covariant type parameter `V' must be invariantly valid on `Both<U,V>(Covariant<None<Contra<V>>>)'
3 // Compiler options: -langversion:future
5 delegate T Covariant<out T> ();
6 delegate void Contra<in T> (T t);
7 delegate void None<T> (T t);
9 delegate void Both<in U, out V> (Covariant<None<Contra<V>>> b);