Re: completion no more working with latest HEADs (emacs and bbdb)

[Arash Esbati <arash@gnu.org>]

Julien Cubizolles <j.cubizolles@free.fr> writes:

> It's not working in GNU Emacs 30.0.50 in emacs -Q with this setup and
> your recipe:
>
> (setq eudc-server-hotlist '(("localhost" . bbdb)))
>
> (add-hook 'message-mode-hook
>           (lambda ()
>             (setq-local completion-at-point-functions
>                         (delq 'message-completion-function
>                               completion-at-point-functions))))
>
> Pressing TAB after typing the beginning of a name in the To: field only
> inserts a tabulation, whereas (bbdb-complete-mail) finds several
> matches.

Thanks for reminding me; I can confirm this behavior and didn't look at
it again back then.  FTR, I have an entry for `eudc-capf-complete' in my
`completion-at-point-functions' in message-mode.  `eudc-capf-complete'
calls `eudc-capf-message-expand-name' which is defined like this:

--8<---------------cut here---------------start------------->8---
(defun eudc-capf-message-expand-name ()
  "Email address completion function for `message-completion-alist'.

[...]"
  (if (or eudc-server eudc-server-hotlist)
      (progn
        (let* ((beg (save-excursion
                      (re-search-backward "\\([:,]\\|^\\)[ \t]*")
                      (match-end 0)))
                    ;; ^^^^^^^^
               (end (point))
               (prefix (save-excursion (buffer-substring-no-properties beg end))))
          (let ((result
                 (eudc-query-with-words (split-string prefix "[ \t]+") t)))
            (when result
              (list beg end
                    (completion-table-with-cache
                     (lambda (_) result) t))))))))
--8<---------------cut here---------------end--------------->8---

While searching back, it picks up the `match-end' which will not work
for the case where you the beginning of the name in your BBDB database.
A change like this should fix it:

--8<---------------cut here---------------start------------->8---
(defun eudc-capf-message-expand-name ()
  "Email address completion function for `message-completion-alist'.

[...]"
  (if (or eudc-server eudc-server-hotlist)
      (progn
        (let* ((beg (save-excursion
                      ;; change follows:
                      (if (member (char-before) '(?, ?: ?\s))
                          (progn
                            (re-search-backward "\\([:,]\\|\\^\\)[ \t]*")
                            (match-end 0))
                        (skip-chars-backward "[:alnum:]"
                                             (line-beginning-position))
                        (point))))
               (end (point))
               (prefix (buffer-substring-no-properties beg end)))
          (let ((result
                 (eudc-query-with-words (split-string prefix "[ \t]+") t)))
            (when result
              (list beg end
                    (completion-table-with-cache
                     (lambda (_) result) t))))))))
--8<---------------cut here---------------end--------------->8---

@Thomas: Can you please have a look at this issue?  I think this is
still related to bug#59314.  TIA.

Best, Arash