[RFC] Two versions of struct _Rb_tree_impl... or not?!

[Paolo Carlini]

Paolo Carlini wrote:

> So, even with Dhruv patch, we would still regress *a lot* wrt
> what we had in 3.3.3.
>
> What we have gained in the meanwhile so important to justify
> this horrible (yes, seems horrible to me, frankly) size
> regression??? Can we fix it???

Ok, sorry, now I see what's really at stake: here we are obviously measuring
only the size of the root, *not* the size of the nodes, which is given 
by the
size of _Rb_tree_node, which has not changed for ages, I think.

Therefore, if I'm right, we are talking about a lot of additional complexity
to spare a few bytes on the memory used by an *entire* map or set object.
Do we really want those two specializations of Rb_tree_impl??

Paolo.