bug#58028: 29.0.50; Ensures no leakage of glyph_matrix

[Eli Zaretskii]

> From: Manuel Giraud <manuel@ledu-giraud.fr>
> Cc: 58028-done@debbugs.gnu.org
> Date: Sun, 25 Sep 2022 18:51:38 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Thanks, installed.
> 
> Thanks.  But I wonder what is the point of this eassert if it have to be
> activated at compile time?

We believe that the assertion will never trigger, so having it in a
production build is a net loss: users could lose their edits.

OTOH, some of the developers (myself included) routinely compile Emacs
with --enable-checking, which activates the assertions.  So if this
assertion is ever contradicted, chances are that one of the developers
will bump into that situation, and will report it (or fix it).

> > Please in the future mention the bug number in the commit log message
> > (I added it for you this time).
> 
> Ok, I'll try to remember this next time.  BTW, how could you do it
> *before* submitting a bug report?

You don't.  But once the bug report has more than a single message,
the number is known, so patches submitted after that should mention
the bug number.