Re: Redisplay hook error backtraces

[Eli Zaretskii]

> Date: Thu, 14 Jul 2022 19:47:25 +0000
> Cc: Eli Zaretskii <eliz@gnu.org>, larsi@gnus.org, emacs-devel@gnu.org
> From: Alan Mackenzie <acm@muc.de>
> 
> > Being in redisplay is usually a good reason why we don't want to let
> > errors escape, even we do care about those errors (and hence we need
> > to use a mechanism like the one you're implementing in order to debug
> > those problems), but there can be other such cases that also use
> > `safe_call` and where we would also want to use your new code.
> 
> There are approximately 38 calls to something like safe_call in the C
> sources, about half of which are in xdisp.c.  That's a lot of scope for
> irritation if non-events continually swamp the real errors in redisplay's
> Lisp hooks.
> 
> It feels like we would want some mechanism to filter out "some" safe_call
> calls, and things are getting complicated fast.  The scope of the
> exercise has already expanded considerably, from just
> fontification-functions to all redisplay hooks.

Alan, you are again over-engineering things.  Assuming that safe__call
is the only interesting gateway for Lisp errors during redisplay
should be good enough, if you in addition test redisplaying_p.