namespace SD { public class Sd { static public void F (bool b) { } } } namespace Foo { using SD; partial class Bar { delegate void f_t (bool b); f_t f = new f_t (Sd.F); } } namespace Foo { partial class Bar { public Bar () {} public static void Main () { if (new Bar ().f == null) throw new System.Exception ("Didn't resolve Sd.F?"); } } }