Re: Why is lexical-binding's global value ignored?

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 29 Jan 2023 20:53:30 -0700
> From: abq@bitrot.link
> Cc: emacs-devel@gnu.org
> 
> On 2023-01-28 23:54, Eli Zaretskii wrote:
> > Wasn't that already explained?  What happens if you say
> > 
> >   (setq-default lexical-binding t)
> > 
> > and then load a Lisp file that expects dynamic-binding by default?
> 
> Then it breaks!

We want to avoid such a breakage.  It is year 2023 out there, but
there's still gobs of code that assumes dynamic binding.

> As I wrote in my response to tomas: “In order to break 
> anything, you would have to do so explicitly, via (setq-default 
> lexical-binding t).”

We decided that was not explicit enough, because many people will not
understand the disastrous consequences.  E.g., even the user's init
file can fail to load.

> Of course, nobody actually does that. Therefore, it would be safe to 
> honor the global value in Emacs 29.

Sorry, we won't, not in Emacs 29.  And that's final.  Please accept
that, even if you disagree.