Re: Declaring 'lexical-binding: nil' obsolete

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Sat, 25 Sep 2021 15:47:45 -0700
> Cc: Stefan Monnier <monnier@iro.umontreal.ca>
> 
> Lexical binding has been with us since Emacs 24.1, released on
> 2012-06-10, almost ten years ago.  In Emacs 28.1, we will have no files
> that do not use lexical-binding.[1]
> 
> I think it is time to formally declare the "lexical-binding:nil" dialect
> of Emacs Lisp obsolete.

Not in Emacs 28, please.  We need to collect experience "in the wild"
before we decide on the next steps, and for now the 100% coverage was
limited to those who track the master branch.  That is not enough,
IMO.  It definitely doesn't justify starting to warn users in Emacs
28.1.

Moreover, in general I see no need to rush this stuff.  There's no
urgency whatsoever.  Dynamic binding is not harmful.  We have much
more important issues on our plate to push forward, let's focus our
efforts on them instead.

>     The plan for phasing out 'lexical-binding:nil' is as follows:
> 
>     Emacs 28.1 - The byte-compiler warns if there is no 'lexical-binding'
>                  cookie.
> 
>     Emacs 30.1 - The byte-compiler warns if there is no 'lexical-binding'
>                  cookie, or if the cookie is 'lexical-binding:nil'.
> 
>     Emacs 32.1 - The warnings remain as before, and 'lexical-binding:t' is
>                  the default.

Please shift the major version numbers by 1 (at the very least).