Position of functions in `completion-at-point-functions'

[Arash Esbati <arash@gnu.org>]

Hi all,

Emacs 30.0.50 has this in text-mode.el (line 155; line break added for
better legibility):

  (when (eq text-mode-ispell-word-completion 'completion-at-point)
    (add-hook 'completion-at-point-functions
              #'ispell-completion-at-point 10 t))

With the latest AUCTeX, the new LaTeX-mode now derives from text-mode
and the value of `completion-at-point-functions' becomes this in a .tex
file:

  (TeX--completion-at-point t ispell-completion-at-point
                            LaTeX--arguments-completion-at-point)

The problem is that `ispell-completion-at-point' kicks in also when
point is inside a macro argument and one actually expects key=val
completion for instance, so I want
`LaTeX--arguments-completion-at-point' before
`ispell-completion-at-point' in that list.  AUCTeX requires Emacs 27
now, and I can fix this by changing this addition in latex.el from:

  (add-hook 'completion-at-point-functions
            #'LaTeX--arguments-completion-at-point t t)

to something like:

  (add-hook 'completion-at-point-functions
            #'LaTeX--arguments-completion-at-point 5 t)

Before making this change to 5 (which is an arbitrary choice): Is there
any kind of range convention where major/minor modes should put their
completion functions?  Any pointer is appreciated.

Best, Arash