Subject: bug#66117: 30.0.50; `find-buffer-visiting' is slow when opening large number of buffers

From: Eli Zaretskii <[email-masked]>
Date: Sun, 17 Dec 2023 13:01:25 +0200

> From: Ihor Radchenko <[email-masked]>
> Cc: [email-masked], [email-masked], [email-masked],
>  [email-masked]
> Date: Sun, 17 Dec 2023 10:52:33 +0000
> 
> Eli Zaretskii <[email-masked]> writes:
> 
> > Maybe I'm confused, but won't this change have at least _some_ effect
> > on Lisp programs?  For example, what about this fragment from the
> > ELisp manual, which describes the effect of
> > make-variable-buffer-local:
> >
> >      A peculiar wrinkle of this feature is that binding the variable
> >      (with ‘let’ or other binding constructs) does not create a
> >      buffer-local binding for it.  Only setting the variable (with ‘set’
> >      or ‘setq’), while the variable does not have a ‘let’-style binding
> >      that was made in the current buffer, does so.
> >
> > Will this case work the same after the change as it did before?
> 
> I read this differently

Differently from what?

> - when you have
> 
>    (let ((var 'val))
>     (make-variable-buffer-local 'var))
> 
> it will not set buffer-local value to 'val.

And before the patch what would have happened?

> And the patch makes `case-fold-search' buffer-local internally. Nothing
> needs to call (make-variable-buffer-local 'case-fold-search).

The patch itself calls make-variable-buffer-local.