bug#64272: 28.1; lisp_file_lexically_bound_p behavior mismatches file local variables

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: LdBeth <andpuke@foxmail.com>,  64272@debbugs.gnu.org
> Date: Sun, 25 Jun 2023 19:00:04 -0400
> 
> > So now let me turn the table and ask: if we are only going to support
> > whitespace before the semicolon, then what exactly are we gaining
> > here?
> 
> I think the main problem is the disconnect between the various ways the
> cookie is recognized, so it may appear to work on one end and fail to
> work on the other, leaving the user rather perplexed.
> 
> So maybe we should export `lisp_file_lexically_bound_p` to ELisp, let
> the byte-compiler (and maybe also `emacs-lisp-mode`) verify that it
> gives the same answer as `hack-local-variables-prop-line`, and emit
> a loud warning if it doesn't.

Patches welcome.