Weird UFC and opCall issues

[Darrell via Digitalmars-d-learn]

Fails with:
     t.d(34): Error: need 'this' for 'opCall' of type 'int()'

Also opCall seems to be required to create a range.

class Test
{
   int opCall()
   {
     return 1;
   }

   @property int front()
   {
     return 2;
   }

   void popFront()
   {
   }

   @property bool empty()
   {
     return false;
   }

};

void main(){
   ubyte [] p1;
   Test();
}