contravariant argument types: wanna?

[BCS]

Hello Walter,

> Andrei Alexandrescu wrote:
> 
>> Second, the new rule is simple: if the overriding function can be
>> called with the overriden function's arguments, it is overriding it.
>> True, things get more complicated when the base class also defines a
>> corresponding overload:
>> 
>> class A {
>> void fun(A);
>> void fun(B);
>> }
>> class B : A {
>> override void fun(A);
>> }
>> This must be either an error, or the case that B.fun overrides both
>> overloads of fun in A.
>> 
> I would really want to get away from the notion of selecting which
> function is overridden based on being a "better" match.
> 

a torture test:

class B
{
   void Fn (D,B) {}
   void Fn (B,D) {}
}

class D : B
{
   void Fn(B,B) {} // override D,B or B,D?
}