using System;

public class Foo[T]
  where T : A
{
  public Test ( t : T) :  void
  {
    Console.WriteLine (t);
    Console.WriteLine (t.GetType ());
    t.Hello ();
  }
}

public class A
{
  public Hello () :  void
  {
    Console.WriteLine ("Hello World");
  }
}

public class B : A
{
}

class X
{
  static Main () :  void
  {
    mutable  foo =  Foo ();
    foo.Test ( B ());
  }
}
/*
BEGIN-OUTPUT
B
B
Hello World
END-OUTPUT
*/