bug#5984: Crash displaying composed characters

[Eli Zaretskii]

> From: Stefan Monnier <monnier@IRO.UMontreal.CA>
> Cc: lekktu@gmail.com, 5984@debbugs.gnu.org
> Date: Fri, 30 Apr 2010 16:47:43 -0400
> 
> >   . Emacs then enters redisplay to display the echo area.  As part of
> [...]
> >   . Further down, autocmp_chars calls the value of
> >     auto-composition-function:
> [...]
> >   . Now the " *Echo Area0*" buffer holds a totally different text,
> >     unbeknownst to autocmp_chars, which still passes the old values 32
> >     and 33 to TEMP_SET_PT_BOTH:
> 
> More generally, this Lisp code could modify any buffer, so preventing
> the load-messages is not a sufficiently reliable solution (tho it might
> be desirable in any case).

I think the patch suggested by Andreas (now installed on the release
branch) does what's necessary.  It's unfortunate minor side-effect is
that the original message from Edebug gets lost; it would be good to
fix that on the trunk.