Re: fsanitize=bounds-strict caught potential error

[Eli Zaretskii]

> From: Andreas Schwab <schwab@linux-m68k.org>
> Cc: Po Lu <luangruo@yahoo.com>,  emacs-devel@gnu.org
> Date: Sun, 05 Dec 2021 16:15:15 +0100
> 
> >> xdisp.c:30394:37: runtime error: index -1 out of bounds for type 
> >> 'iterator_stack_entry [5]'
> >
> > The compiler doesn't know enough to realize that this code can never
> > be executed with it->sp < 1.  This code is there since 2003, and never
> > gave us any trouble.
> 
> It is a runtime error, thus the erroneous access is actually being
> executed.

Then let's put an assertion there and find the culprit.  Maybe it's
the min-width feature, which is new on master.