Re: Can't set conditional break point using AREF/NILP

[Eli Zaretskii <eliz@gnu.org>]

> From: Sean Whitton <spwhitton@spwhitton.name>
> Date: Sat, 01 Jan 2022 14:49:05 -0700
> 
> >>     condition NN NILP (AREF (entity, FONT_WEIGHT_INDEX))
> >>
> >> but this didn't work -- is it possible to do something like that?
> >
> > It should be possible if your Emacs was compiled with -g3.
> 
> Can confirm mine is.
> 
> > Perhaps try
> >
> >   condition NN AREF (entity, FONT_WEIGHT_INDEX) == Qnil
> >
> > instead.
> 
> This fails in the same way.  This is what I see:
> 
> Breakpoint 2 at 0x335d30: file ftfont.c, line 231.
> (gdb) condition 2 AREF (entity, FONT_WEIGHT_INDEX) == Qnil
> (gdb) r
> `/home/spwhitton/src/emacs/src/emacs' has changed; re-reading symbols.
> Starting program: /home/spwhitton/src/emacs/src/emacs
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
> [New Thread 0x7ffff15c4700 (LWP 2073615)]
> [New Thread 0x7ffff0bca700 (LWP 2073616)]
> [New Thread 0x7fffebfff700 (LWP 2073617)]
> [New Thread 0x7fffeb254700 (LWP 2073618)]
> [New Thread 0x7fffea8c3700 (LWP 2073619)]
> [New Thread 0x7fffe9f32700 (LWP 2073620)]
> Error in testing breakpoint condition:
> Couldn't get registers: No such process.

This error message already says it won't work, although I don't
understand why.  The "No such process" part is especially worrisome.
It works here, FWIW.

What version of GDB is that, and was it built with Python support?
I have GDB 11.1 here.

Also, did you perhaps use the --enable-check-lisp-object-type
configure-time switch?  If so, please rebuild without it.