bug#66706: [PATCH] Automatic elisp dialect insertion

[Eli Zaretskii]

> From: Michael Heerdegen <michael_heerdegen@web.de>
> Cc: dmitry@gutov.dev,  mattias.engdegard@gmail.com,  66706@debbugs.gnu.org,
>   stefankangas@gmail.com,  monnier@iro.umontreal.ca
> Date: Fri, 27 Oct 2023 05:14:11 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > > Short version of my reply: Emacs users are a different group than Elisp
> > > package developers.  Let's help them by forcing a lexical binding cookie
> > > in the config file instead of simply making their Emacs potentially not
> > > starting up.
> >
> > If this is about init files, we could instead make processing init
> > files assume lexical-binding by default.
> 
> That's exactly what we should avoid because it can make Emacs not start
> up for init files that require the current default of dynamical binding.

How many of init files do indeed require dynamic binding?  And why?

If a new Emacs version refuses to start because something in the init
files goes against some new Emacs feature, we have --debug-init and
other facilities to debug and fix those.  Why should lexical-binding
be considered different from any other backward-incompatible change
that we sometimes do?

In any case, how will injecting the cookie help those users, exactly?
If people who write init files don't understand the implications of
lexical-binding, their Emacs will fail to start, something that you
think is a catastrophe.  And if they do understand it, their init
files are already compatible with lexical-binding.

> We also should not assume dynamical binding: lexical binding is the
> default.  Emacs should not guess: it should ask the user and then add a
> cookie.  That's my point.

Your point seems to be incompatible with our plan, which is to turn on
lexical-binding by default at some point.  We don't want to have a
schism of two separate flavors of Lisp, we want only one.  The current
situation is a transitional period, not the ideal.  You seem to be
suggesting that we should keep this situation forever, and that is not
what we decided, AFAIU.