NotNull pointers

[Daniel Murphy]

One thing that hasn't been mentioned is that asserts do not always terminate 
the program.  Should this program segfault?

(Not a great example, because while it does segfault inside A.fun's 
contract, the contract handler's catch-all ignores it and contines, but 
that's a different issue)

class X
{
  invariant() {}
}

class A
{
  void fun(X x)
  in
  {
    assert(x);
  }
  body
  {
  }
}

class B : A
{
  void fun(X x)
  in
  {
  }
  body
  {
  }
}

void main()
{
  auto b = new B();
  b.fun(null);
}