bug#43725: 28.0.50; Include feature/native-comp into master

[Eli Zaretskii]

> From: Andrea Corallo <akrl@sdf.org>
> Cc: larsi@gnus.org, monnier@iro.umontreal.ca, 43725@debbugs.gnu.org
> Date: Tue, 16 Feb 2021 21:13:07 +0000
> 
> Addressing some easy part of the review to close the day.

Thanks.

> > Likewise, this is unsafe because a fixnum can be larger than INT_MAX:
> >
> >   +  if (!FIXNUMP (idx))
> >   +    xsignal1 (Qnative_ice,
> >   +             build_string ("inconsistent data relocation container"));
> >   +  reloc.idx = gcc_jit_context_new_rvalue_from_int (comp.ctxt,
> >   +                                                  comp.ptrdiff_type,
> >   +                                                  XFIXNUM (idx)); 
> > <<<<<<<<
> >
> > (There are several more calls with the same problem.)
> 
> Should we never trust in C a value coming from a Lisp_Object even if is
> supposed to be constructed on purpose?

We can trust that if we indeed make the value explicitly, but if
there's at least a tiny chance to get a value that's too large, at
least an assertion would be a good idea.