bug#65491: [PATCH] Improve performance allocating vectors

[Eli Zaretskii]

> From: Mattias Engdegård <mattias.engdegard@gmail.com>
> Date: Mon, 18 Sep 2023 18:10:47 +0200
> Cc: Paul Eggert <eggert@cs.ucla.edu>,
>  65491@debbugs.gnu.org,
>  monnier@iro.umontreal.ca
> 
> 17 sep. 2023 kl. 18.44 skrev Eli Zaretskii <eliz@gnu.org>:
> 
> > Feel free to add any comments you find useful, that is always welcome.
> > But comments about complicated code have one downside: they need to be
> > updated when the code changes, and people forget to do that...
> 
> Eli and Paul, thank you very much. I'm reapplying the patches (that we now 
> know shouldn't cause warnings), with added comments with respect to the 
> vanishing subtrahend in -with-wide-int builds.

Fine with me, but I still hope Paul will do good on his proposal to
add comments...

> The conversion at the other end, TAG_PTR, suffers from the same potential 
> problem but in reverse, which is perhaps less obvious to the casual C 
> programmer but nevertheless a danger of the same kind, so we'd better do 
> something about it as well. I'll be back with a proposed patch.

Thanks.