bug#61504: 29.0.60; executing byte-code from previous build causes SIGSEGV crash

[Eli Zaretskii]

> Date: Tue, 14 Feb 2023 09:29:32 +0000
> From: Gregory Heytings <gregory@heytings.org>
> cc: Eli Zaretskii <eliz@gnu.org>, 61504@debbugs.gnu.org
> 
> > There seems to be a byte-code change between versions 
> > 0ec0a610ed226419269f519021cbe8fb2dde2ed5 (old) and 
> > a4aa32bdfff7aaf54efbacbb04b7f2b52fef92a7 (new) which causes the new 
> > version to crash with SIGSEGV when executing certain code from an .elc 
> > built using the old version. Recompiling the file with the new version 
> > causes the new .elc to work correctly.
> >
> 
> The bytecode did not change, but the byte codes generated by the 
> save-restriction form did change.
> 
> Now that I think of it again, it is possible make that change while 
> preserving backward compatibility.
> 
> Eli, what do you think of the attached patch?  It restores the 'unbind 1' 
> at the end of save-restriction, and puts the two data elements into a cons 
> instead of pushing them separately.  (Of course this passes make and make 
> check, with and without native compilation.)

I guess we have no choice.

Mattias, Stefan: any better alternatives, or comments/objections?