Support completion-lazy-hilit and completion-lazy-hilit-fn for Emacs 30.

[okamsn]

This feature allows highlighting to occur later instead of being
performed by the completion style immediately.

• Move logic for highlighting a single candidate from
  prescient--highlight-matches to prescient--highlight-candidate.

• Rename prescient--highlight-matches to
  prescient--highlight-candidates, which now applies the new
  function to a list of candidates.

  • Keep this function to support
    prescient-completion-highlight-matches, which is now obsolete.

See:

• Prescient issue Add support for completion-lazy-hilit #152
  (Add support for completion-lazy-hilit #152)

• Emacs bug #47711
  (https://debbugs.gnu.org/cgi/bugreport.cgi?bug=47711)

• Emacs commit dfffb91a70532ac0021648ba692336331cbe0499
  (https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=dfffb91a70532ac0021648ba692336331cbe0499),

• Vertico commit b11040e1e9c1a4e5178800a0d0925aeeb72dd027
  (minad/vertico@b11040e)

• This Prescient PR Support completion-lazy-hilit and completion-lazy-hilit-fn for Emacs 30. #153.

[raxod502]

Can we really label the variable as obsolete if it is still needed in older Emacs versions which we still support?

Perhaps it would be better to use the new variable if available, but otherwise fall back to prescient-completion-highlight-matches, until we stop supporting versions of Emacs that don't have the new variable?

[okamsn]

Can we really label the variable as obsolete if it is still needed in older Emacs versions which we still support?

Perhaps it would be better to use the new variable if available, but otherwise fall back to prescient-completion-highlight-matches, until we stop supporting versions of Emacs that don't have the new variable?

That seems reasonable to me. I tried searching for uses of it on GitHub, but didn't find any.

How does it look now?

[minad]

Perhaps it would be better to use the new variable if available, but otherwise fall back to prescient-completion-highlight-matches, until we stop supporting versions of Emacs that don't have the new variable?

That seems reasonable to me. I tried searching for uses of it on GitHub, but didn't find any.

completion-lazy-hilit can be used even on old versions of Emacs, see the implementation of Vertico. Given that prescient-completion-highlight-matches is not used anywhere one can as well remove the variable. It doesn't really function as a fallback for lazy highlighting.

On the other hand it may make sense to keep the variable as is, such that it always disables highlighting completely (even if completion-lazy-hilit is set). This would preserve the current meaning and could be helpful if users don't want highlighting at all.

How does it look now?

Looks good to me!

[raxod502]

I tried searching for uses of it on GitHub, but didn't find any.

Yea, I would just be worried because it's actually kind of uncommon for people to put their Emacs configs on the public internet, there are a lot, but probably the vast majority are just on people's laptops or private servers.

[raxod502]

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