// CS0312: The type `E?' cannot be used as type parameter `T' in the generic type or method `C<System.Enum>.Foo<T>(T)'. The nullable type `E?' does not satisfy constraint `System.Enum' // Line: 16 enum E { } class C<U> { static void Foo<T> (T value) where T : U { } static void Test (E? s) { C<System.Enum>.Foo (s); } }