Re: The poor quality of Emacs's backtraces

[Eli Zaretskii]

> From: Ihor Radchenko <yantar92@posteo.net>
> Cc: Alan Mackenzie <acm@muc.de>, emacs-devel@gnu.org
> Date: Fri, 14 Jul 2023 08:00:17 +0000
> 
> Mattias Engdegård <mattias.engdegard@gmail.com> writes:
> 
> >> test suite truncating every line at ~70 characters.  (Why is this done?)
> >
> > I agree, that's annoying. We have to truncate at some point or we'll be 
> > treated to dumps of impractical size before we know it, but 70 chars is 
> > pretty useless.
> 
> It would be nice if the backtraces used `pp' instead of dumb truncation.

That would be a definite improvement, but please don't forget that the
backtrace must be available in many situations where Emacs is
unstable.  In particular, it is completely unacceptable for a
backtrace to cause Emacs to abort, e.g., because it attempts to
display some invalid Lisp object.  (Yes, we had such problems
recently, due to the fact that the backtrace nowadays uses cl-print.)

So whatever you do to enhance the backtrace, please take care of
catching any exceptions and falling back to the good-old simple
backtrace.