Resolution of B-2 not reflected in B-6 (aka covariant returns)

[Jason Merrill]

>>>>> Martin von Loewis <loewis at informatik.hu-berlin.de> writes:

 >> It seems unnecessary to force a new entry if the return types are related
 >> by single inheritance.

 > In the B-2 discussion, the notes say

 > # Agreement was reached to avoid the complication of eliminating some
 > # of the Vtable entries. Thus, the Vtable will have one entry for each
 > # accessible return type of a covariant virtual function.

 > I agree with that resolution; it follows that a new slot is allocated
 > even if there are no return adjustments.

I don't think that's what was meant by the resolution; I think it was
referring to our decision not to use Daveed's scheme for returning multiple
types from a single function.

It is trivial to determine whether or not an adjustment is necessary, and I
think we might as well.  What do other people think?

Jason