Re: warnings compiling emacs28 with gcc 12.1

[Eli Zaretskii <eliz@gnu.org>]

> From: Óscar Fuentes <ofv@wanadoo.es>
> Date: Thu, 28 Jul 2022 19:12:00 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> and there's another one about free that looks a bit scary:
> >> 
> >>    alloc.c: In function ‘lisp_free’:
> >>    alloc.c:1052:3: warning: pointer ‘block’ used after ‘free’ [-Wuse-after-free]
> >>     1052 |   mem_delete (mem_find (block));
> >>          |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >>    alloc.c:1050:3: note: call to ‘free’ here
> >>     1050 |   free (block);
> >>          |   ^~~~~~~~~~~~
> >
> > Another nonsense.  Look in mem_find, and you will see that it uses its
> > argument as just a number, it never dereferences it.
> 
> The warning is not about dereferencing the pointer.

What other problems could be caused by using it after freeing it?