bug#59314: 29.0.50; EUDC and message-mode header completion

[Eric Abrahamsen]

Thomas Fitzsimmons <fitzsim@fitzsim.org> writes:

> Hi Eric,
>
> Eric Abrahamsen <eric@ericabrahamsen.net> writes:
>
>> On 11/16/22 14:18 PM, Thomas Fitzsimmons wrote:
>>> Hi Eric,
>>>
>>> Thanks for filing this.
>>>
>>> Eric Abrahamsen <eric@ericabrahamsen.net> writes:
>>>
>>>> Address completion in message-mode has stopped working in master,
>>>> possibly as a result of 0e25a39e69acca0324c326ea8e46b1725594bff5. This
>>>> has been reported for several contact-management backends that expect to
>>>> have their completions available with <TAB>.
>>>>
>>>> `completion-at-point-functions' contains '(eudc-capf-complete
>>>> message-completion-function t) at this point -- `eudc-capf-complete'
>>>> returns no matches, and no other functions in the list are consulted.
>>>
>>> I just checked and I didn't think the recent patch I pushed,
>>> 0e25a39e6..., should have affected completion-at-point-functions.  It
>>> did change the default of eudc-server-hotlist from `nil' to
>>> `(("localhost" . ecomplete) ("localhost" . mailabbrev))".  I thought
>>> that should only affect EUDC users who have not customized
>>> eudc-server-hotlist.
>>>
>>> `eudc-capf-complete' was added to `message-mode' in commit
>>> 620ac6735...  I'm pretty sure that commenting out this line in
>>> message.el will restore prior behaviour, but I don't yet know what prior
>>> behaviour should be (see below).
>>>
>>> (add-hook 'completion-at-point-functions #'message-completion-function nil 
>>> t)
>>>
>>>> On gnus.general, someone using BBDB and corfu reported that this recipe
>>>> fixed the problem:
>>>>
>>>>   (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))))
>>>>
>>>> Someone else *not* using corfu reported that that didn't work for them.
>>>> Dunno.
>>>
>>> I'm not sure what the out-of-the-box behaviour here is meant to be.  Can
>>> you make a recipe starting from "emacs -Q" (including adding dummy email
>>> addresses somewhere) that makes completion work how you want it to?  For
>>> me:
>>>
>>> emacs -Q
>>> C-x m TAB
>>>
>>> inserts four spaces and prints in *Messages*:
>>>
>>> Loading eudcb-ecomplete...done
>>> Loading eudcb-mailabbrev...done
>>>
>>> (Those are new, due to 0e25a39e6... but I thought should be harmless.)
>>
>> Yuck, it's been a long time since I looked at this...
>>
>> In emacs -Q, message-mode `completion-at-point-functions' is:
>>
>> (eudc-capf-complete message-completion-function t)
>>
>> Actually that's what it is in my regular Emacs, as well. All I'd need
>> for EBDB (and BBDB and everything else) is for
>> `message-completion-function' to get called, which it isn't. I believe
>> you could allow this by having `eudc-capf-complete' return nil, or have
>> `eudc-capf-message-expand-name' return a `(list beg end <table>)'
>> structure that includes the prop `:exclusive 'no' at the end of it. That
>> would allow a fallthrough to the next function.
>
> Ah, OK, that's what happened then.  The most recent patch I pushed made
> `eudc-server-hotlist' non-nil by default, which makes
> `eudc-capf-message-expand-name' do something other than return nil.
>
> Can you try just (setq eudc-server-hotlist nil) and confirm that avoids
> the breakage?
>
> If it does, I'll revert that part of the patch for now.

It does! Thanks.