Re: lexical-binding is turned on in more use cases

[Noam Postavsky <npostavs@gmail.com>]

On Tue, 10 Mar 2020 at 19:42, Michael Heerdegen
<michael_heerdegen@web.de> wrote:

> (defun my-make-counter ()
>   (let ((counter 0))
>     (lambda () (setq counter (1+ counter)))))
>
> (setq mc (my-make-counter))

> If you eval (my-make-counter) with lexical-binding off, the result is
> not functional.

Actually, it only fails if you evaluate the (defun my-make-counter
...) with lexical-binding off.

> Were does M-: break for you with the change?

Please, let's not go in circles. An example was already given
upthread: https://lists.gnu.org/r/emacs-devel/2020-03/msg00219.html

Essentially some cc-mode variables are only declared dynamic locally
within individual files. Without lexical binding the only difference
this causes is that they are unbound at top level; but with
lexical-binding, outside of the declaring files (e.g., in M-:
expressions), let-binding those variables doesn't bind the value
dynamically.