bug#53058: etc/DEBUG could say more about --enable-check-lisp-object-type

[Eli Zaretskii]

> From: Sean Whitton <spwhitton@spwhitton.name>
> Cc: 53058@debbugs.gnu.org
> Date: Fri, 07 Jan 2022 13:41:52 -0700
> 
> To me, conditionalising break points is a fundamental debugging action,
> something that a beginner is likely to want to do.  And it's Emacs, so
> chances are those conditions will involve Lisp objects.  So having
> instructions aimed at someone just getting started telling you to use a
> flag which makes that basic debugging action much less likely to work
> seems worth improving.  Do you have any other ideas as to how that could
> be done?

The reasons for the problem in your case is not known: NILP should
have worked, as did the comparison with Qnil.  Until we understand why
those didn't work, I don't see how we can say anything in etc/DEBUG
that would both be useful and important/general enough to have there.

My best advice is to try to understand why those conditions didn't
work on your system.  Maybe someone here knowns, or maybe you should
ask on the GDB mailing list (gdb@sourceware.org).