including (compat-function completion-metadata-get) in all-the-icons-completion breaks corfu + cape

[maxecharel]

Hi @minad and community,
I move that here from minad/marginalia#175, sorry for the possible mismatch. I've cloned and adjusted all-the-icons-completion to make it compatible with the new version of marginalia (see previous link). It works, but I noticed a very specific problem that appears when I use this modified version of all-the-icons-completion (disappears when I go back to the original version): when using ESS-R + corfu + cape, I get the following errors:

Error running timer ‘corfu--auto-complete-deferred’: (wrong-type-argument arrayp nil)
Error in post-command-hook (corfu--post-command): (wrong-type-argument arrayp nil)

Interestingly, I do not have this problem with e.g. Elisp or eglot + pyright. I therefore conclude (maybe erroneously) that the problem is coming from the fact that in ESS-R, I use company backends that I convert into capfs via cape.

Here's a backtrace:

Debugger entered--Lisp error: (wrong-type-argument arrayp nil)
  replace-regexp-in-string("[ \11]*\n[ \11]*" " " nil)
  corfu--format-candidates(((#("lims" 0 2 (face orderless-match-face-0)) #(" * " 0 1 (display (space :width (4)) face (:weight bold :foreground "#ECBE7B")) 1 2 (display (image :type svg :data "<svg width=\"14\" height=\"17.0\" version=\"1.1\" xmlns=..." :scale 1 :ascent center :transform-smoothing t)) 2 3 (display (space :width (3)) face (:weight bold :foreground "#ECBE7B"))) nil) (#("line" 0 2 (face orderless-match-face-0)) #(" * " 0 1 (display (space :width (4)) face (:weight bold :foreground "#ECBE7B")) 1 2 (display (image :type svg :data "<svg width=\"14\" height=\"17.0\" version=\"1.1\" xmlns=..." :scale 1 :ascent center :transform-smoothing t)) 2 3 (display (space :width (3)) face (:weight bold :foreground "#ECBE7B"))) nil) (#("list" 0 2 (face orderless-match-face-0)) #(" * " 0 1 (display (space :width (4)) face (:weight bold :foreground "#ECBE7B")) 1 2 (display (image :type svg :data "<svg width=\"14\" height=\"17.0\" version=\"1.1\" xmlns=..." :scale 1 :ascent center :transform-smoothing t)) 2 3 (display (space :width (3)) face (:weight bold :foreground "#ECBE7B"))) nil) (#("lines" 0 2 (face orderless-match-face-0)) #(" * " 0 1 (display (space :width (4)) face (:weight bold :foreground "#ECBE7B")) 1 2 (display (image :type svg :data "<svg width=\"14\" height=\"17.0\" version=\"1.1\" xmlns=..." :scale 1 :ascent center :transform-smoothing t)) 2 3 (display (space :width (3)) face (:weight bold :foreground "#ECBE7B"))) nil) (#("library" 0 2 (face orderless-match-face-0)) #(" * " 0 1 (display (space :width (4)) face (:weight bold :foreground "#ECBE7B")) 1 2 (display (image :type svg :data "<svg width=\"14\" height=\"17.0\" version=\"1.1\" xmlns=..." :scale 1 :ascent center :transform-smoothing t)) 2 3 (display (space :width (3)) face (:weight bold :foreground "#ECBE7B"))) nil) (#("licence" 0 2 (face orderless-match-face-0)) #(" * " 0 1 (display (space :width (4)) face (:weight bold :foreground "#ECBE7B")) 1 2 (display (image :type svg :data "<svg width=\"14\" height=\"17.0\" version=\"1.1\" xmlns=..." :scale 1 :ascent center :transform-smoothing t)) 2 3 (display (space :width (3)) face (:weight bold :foreground "#ECBE7B"))) nil) (#("license" 0 2 (face orderless-match-face-0)) #(" * " 0 1 (display (space :width (4)) face (:weight bold :foreground "#ECBE7B")) 1 2 (display (image :type svg :data "<svg width=\"14\" height=\"17.0\" version=\"1.1\" xmlns=..." :scale 1 :ascent center :transform-smoothing t)) 2 3 (display (space :width (3)) face (:weight bold :foreground "#ECBE7B"))) nil) (#("list2DF" 0 2 (face orderless-match-face-0)) #(" * " 0 1 (display (space :width (4)) face (:weight bold :foreground "#ECBE7B")) 1 2 (display (image :type svg :data "<svg width=\"14\" height=\"17.0\" version=\"1.1\" xmlns=..." :scale 1 :ascent center :transform-smoothing t)) 2 3 (display (space :width (3)) face (:weight bold :foreground "#ECBE7B"))) nil) (#("list2env" 0 2 (face orderless-match-face-0)) #(" * " 0 1 (display (space :width (4)) face (:weight bold :foreground "#ECBE7B")) 1 2 (display (image :type svg :data "<svg width=\"14\" height=\"17.0\" version=\"1.1\" xmlns=..." :scale 1 :ascent center :transform-smoothing t)) 2 3 (display (space :width (3)) face (:weight bold :foreground "#ECBE7B"))) nil) (#("list.dirs" 0 2 (face orderless-match-face-0)) #(" * " 0 1 (display (space :width (4)) face (:weight bold :foreground "#ECBE7B")) 1 2 (display (image :type svg :data "<svg width=\"14\" height=\"17.0\" version=\"1.1\" xmlns=..." :scale 1 :ascent center :transform-smoothing t)) 2 3 (display (space :width (3)) face (:weight bold :foreground "#ECBE7B"))) nil)))
  corfu--candidates-popup((#<window 3 on test_corfu_after_all-the-icons-completion_fix.R> 1 (28 . 0) 0 nil 1 (4 . 0) nil (0 . 0) (7 . 17)))
  #f(compiled-function (&optional auto) #<bytecode -0x1f6420cef409e495>)(auto)
  apply(#f(compiled-function (&optional auto) #<bytecode -0x1f6420cef409e495>) auto)
  #f(compiled-function (&rest args) #<bytecode -0x11808fa36a2b0be5>)(auto)
  apply(#f(compiled-function (&rest args) #<bytecode -0x11808fa36a2b0be5>) auto)
  corfu--exhibit(auto)
  corfu--auto-complete-deferred((#<window 3 on test_corfu_after_all-the-icons-completion_fix.R> #<buffer test_corfu_after_all-the-icons-completion_fix.R> 15 3))
  apply(corfu--auto-complete-deferred (#<window 3 on test_corfu_after_all-the-icons-completion_fix.R> #<buffer test_corfu_after_all-the-icons-completion_fix.R> 15 3))
  timer-event-handler([t 26254 18401 820228 nil corfu--auto-complete-deferred ((#<window 3 on test_corfu_after_all-the-icons-completion_fix.R> #<buffer test_corfu_after_all-the-icons-completion_fix.R> 15 3)) nil 852000 nil])

Any suggestion regarding the source of the issue and how to solve it?

Many thanks!

[minad]

It seems that the affixation function returns an invalid result, where one of the elements is nil. The affixation function should return a list of the form (("cand" "prefix" "suffix") ...). All the elements must be strings. The empty string should be used if no prefix or suffix is present. However I cannot tell you precisely where the problem lies.

[minad]

The main problem here is that all-the-icons-completion (like Marginalia) should not even activate in Corfu. This has been fixed here: minad/corfu@062e4f0

(However there may still be a small bug in all-the-icons-completion since its affixation function seems to return an invalid result under some circumstances, as I had mentioned in my other comment. Now we just make sure to not trigger it.)

[maxecharel]

Just upgraded corfu, and now it works as expected in ESS-R+corfu+cape. Amazing, thanks @minad !