Re: Emacs design and architecture

[Eli Zaretskii]

> From: Richard Stallman <rms@gnu.org>
> Cc: emacs-devel@gnu.org
> Date: Wed, 20 Sep 2023 14:35:41 -0400
> 
> What would be problematical is calling from within the parts
> of redisplay that alter the display matrices.  An error there
> would be hard to recover.  It could crash.
> 
> It is many years since I looked at that code, but ISTR that the
> calls for font lock are in the outer parts, specifically to
> avoid this danger.

No, they are called from where the glyph matrices are constructed.
But we catch Lisp errors when we call jit-lock (and any other Lisp)
from the display code, so any error just causes a message in
*Messages* (and might leave the text unfontified).  So it is not
dangerous.