Thomas Fitzsimmons <fitzsim@fitzsim.org> writes:

> [...]
> If I remove this line from message.el:
>
> (add-hook 'completion-at-point-functions #'eudc-capf-complete -1 t)
>
> and rebuild Emacs, then my recipe works, via:
>
> message-tab -...-> message-expand-name -> eudc-expand-inline
>
> The EUDC multi-selector UI is invoked allowing me to choose between
> emacs-ert-test-3 and emacs-ert-test-4, and the full name and email
> address is inserted correctly.  This is with completion-styles left at
> its default value.
>
> So that's one code path validated, phew.
> [...]

There are two ends to this, I think.

For one, you are no longer adding `eudc-capf-complete` to
`completion-at-point-functions` in message mode. This seems fine given
that we are not there yet to make `eudc-capf-complete` the default thing
to happen in 29.

OTOH, `eudc-capf-complete` is now just sitting there for people to use
it. The docstring, and the NEWS entry advertise it for adding to
`completion-at-point-functions`. If & when someone does that, it won't
work as expected, as you & I just figured, because `completion-styles`
has a default value aimed at single-word replacements (such as for
programming language keywords, or prose words from a dictionary), but
not for more complex, multi-word replacements (such as email addresses).
The `substring` entry is needed for this use-case.

To make this work, I am hence attaching a patch (relative to the tip of
master as of this writing), which sets `completion-style` from
`eudc-capf-complete`. The modification is done when the user has not
modified its value (assuming that a sensible value will have been set by
the user). If you need a patch on top of the 29 branch, please don't
hesitate to drop me a note.


Hoping to have helped, and looking forward to your thoughts,

  --alexander