Vertico not offering function completions for M-: eval-expression?

[DivineDominion]

When I switched from selectrum to vertico, I noticed that when I hit M-: to eval an expression, the tab completion of function names doesn't appear to use vertico at all. Instead a new window with a list of completion candidates pops up.

Am I missing a setting? I looked for hints in the README and found that vertico doesn't seem to hook into this by default.

"Fixes" by other vertico users can be found e.g. here:
https://libredd.it/r/emacs/comments/opf1kk/switched_to_vertigo_consult_and_minibuffer/?sort=top

Is there a reason why this is not part of vertico-mode's setup of hooks?

[minad]

Completion-at-point/completion-in-region is an orthogonal concern to minibuffer completion. Therefore it is not provided here. There are many possible frontends for completion-at-point/completion-in-region, for example Corfu.

From the perspective of vertico the canonical solution if you want to use the minibuffer is consult-completion-in-region. This is not a fix or a hack - consult-completion-in-region is the proper implementation for this feature.

I should add - maybe you also tried Selectrum, which implements completion-in-region support via its selectrum-completion-in-region function. The two functions selectrum-completion-in-region and consult-completion-in-region are mostly equivalent, with the only difference that consult-completion-in-region is completion system agnostic (works with icomplete, vertico, etc). Therefore it fits the spirit of Consult and Vertico can get by without its own implementation.

[DivineDominion]

Thanks for explaining, @minad! I didn't realize that these were two different things because in both cases I am typing in the minibuffer (or so it seems)

The code by @karthink from the above mentioned link works, apparently more-or-less in the same way selectrum installs itself for this case:

  (add-hook 'vertico-mode-hook (lambda ()
                                 (setq completion-in-region-function
                                       (if vertico-mode
                                           #'consult-completion-in-region
                                         #'completion--in-region))))

[minad]

This is also documented in the README: https://github.com/minad/vertico#completion-at-point-and-completion-in-region

[DivineDominion]

@minad I now realize that, too. Problem was I didn't know this is used by eval-expression. I assume that the question some users have is not "how do I enable Vertico for my completion-in-region-function?", but "how do I enable vertico for eval-expression completion?"

[dmitrym0]

I assume that the question some users have is not "how do I enable Vertico for my completion-in-region-function?", but "how do I enable vertico for eval-expression completion?"

That is correct. I read through the eval-expression paragraph (int the README) a couple of times but it did not click for me. If I may humbly suggest to word it more explicitly?

[DivineDominion]

@dmitrym0 So with the changes from https://github.com/minad/vertico/pull/148/files and the more recent README version, what would you like to see there? @minad accepted my changes after this discussion, so if you have a suggestion that would've been helpful for "past you", I'd suggest to open a PR :)

[dmitrym0]

@dmitrym0 So with the changes from https://github.com/minad/vertico/pull/148/files and the more recent README version, what would you like to see there? @minad accepted my changes after this discussion, so if you have a suggestion that would've been helpful for "past you", I'd suggest to open a PR :)

I spent some time thinking about it -- I couldn't come with anything better without overloading the already large README. This should be fine, thanks for the documentation :)