Re: Making Emacs Lisp easier to debug

[Alan Mackenzie <acm@muc.de>]

Hello, Eli.

On Sat, Nov 11, 2023 at 08:52:12 +0200, Eli Zaretskii wrote:
> > Date: Fri, 10 Nov 2023 20:56:54 +0000
> > From: Alan Mackenzie <acm@muc.de>

> > (ii) Edebugging font locking code.  It would be nice to be able to debug
> > font locking code which is being called from redisplay, as well as other
> > hooks which are also called from redisplay.  At the moment this isn't
> > possible.  To make it possible would require redisplay to become
> > reentrant, so that a frame or window in the inner redisplay call 
> > could be where debugging of the outer redisplay call happens.  I don't
> > know how practicable it would be to enhance redisplay for this (it is
> > certainly possible).  Has anybody ever looked into this before?

> Yes, see jit-lock-debug-mode.  (It's described in the ELisp manual.)

:-)  I really meant has anybody looked into making redisplay reentrant.

As for jit-lock-debug-mode, it doesn't work in my setup.  It just
disables font-lock totally.  I suspect its timer isn't triggering for
some reason.  I haven't actually tried it yet in emacs -Q.

-- 
Alan Mackenzie (Nuremberg, Germany).