bug#60333: [PATCH] whitespace: Update bob, eob markers in base and indirect buffers

[Eli Zaretskii <eliz@gnu.org>]

> Cc: 60333@debbugs.gnu.org
> Date: Thu, 29 Dec 2022 03:11:11 -0500
> From: Richard Hansen <rhansen@rhansen.org>
> 
> On 12/28/22 09:44, Stefan Monnier wrote:
> >>> "Expose" is the wrong term, because we don't have that info ready to
> >>> be exposed.  We'd either have to create&maintain that list, or compute
> >>> it on-demand when requested.
> > [...]
> >> 1. Maintain internal indirect buffer list associated with buffers in C
> > 
> > That's the "create&maintain that list" option.
> > Personally I don't like it: I'd like to reduce the amount of support we
> > provide in C for indirect buffers rather than increase it.
> 
> What alternative would you prefer?
> 
> How about something like this in a shared location (e.g., simple.el next 
> to `clone-indirect-buffer'):
> 
>      (defvar indirect-buffers--cached nil)
> 
>      (defun indirect-buffers--invalidate-cache ()
>        (setq indirect-buffers--cached nil)
>        (remove-hook 'buffer-list-update-hook
>                     #'indirect-buffers--invalidate-cache))
> 
>      (defun indirect-buffers ()
>        (unless indirect-buffers--cached
>          (setq indirect-buffers--cached '(nil nil))
>          (dolist (buf (buffer-list))
>            (let ((base (buffer-base-buffer buf)))
>               (when base
>                (push buf (plist-get indirect-buffers--cached base)))))
>          (add-hook 'buffer-list-update-hook
>                    #'indirect-buffers--invalidate-cache))
>        indirect-buffers--cached)
> 
> Other options I can see:
> 
>    #1: Apply this patch as-is, keep Org as-is, and live with the code 
> duplication.
>    #2: Reject this patch and keep Org as-is.
>    #3: Advise `make-indirect-buffer'.  The advice would record new 
> indirect buffers and add a `kill-buffer-hook' function to clean up the 
> entry.  (Note, however, that `make-indirect-buffer' is a primitive 
> function.)
>    #4: Fix Bug#46982.  (One possible approach that maintains backwards 
> compatibility:  Teach `after-change-functions' to look for a symbol 
> property that means "run me not just for changes made in this buffer, 
> but also if a change is made in this buffer's base/indirect buffer".)

And this.