bug#72624: 31.0.50; minor-mode-overriding-map-alist doesn't have higher priority than local map, which differs from docs

[Eli Zaretskii <eliz@gnu.org>]

> Date: Wed, 14 Aug 2024 17:45:03 +0200 (CEST)
> From: mr.meowking--- via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> NOTE: please view
> https://codeberg.org/meow_king/typst-ts-mode/issues/6#issuecomment-2174390
> for rendered markdown view.
> 
> According to docs `(elisp) Active Keymaps` :
> 
> > Emacs contains many keymaps, but at any time only a few keymaps are
> “active”.  When Emacs receives user input, it translates the input event
> (*note Translation Keymaps::), and looks for a key binding in the active
> keymaps.
> >
> >   Usually, the active keymaps are: (i) the keymap specified by the
> ‘keymap’ property, (ii) the keymaps of enabled minor modes, (iii) the
> current buffer's local keymap, and (iv) the global keymap, in that
> order.  Emacs searches for each input key sequence in all these keymaps.
> >
> >   Of these usual keymaps, the highest-precedence one is specified by
> the ‘keymap’ text or overlay property at point, if any.  (For a mouse
> input event, Emacs uses the event position instead of point; *note
> Searching Keymaps::.)
> >
> >   Next in precedence are keymaps specified by enabled minor modes.
> These keymaps, if any, are specified by the variables
> ‘emulation-mode-map-alists’, ‘minor-mode-overriding-map-alist’, and
> ‘minor-mode-map-alist’.  *Note Controlling Active Maps::.
> >
> >   Next in precedence is the buffer's “local keymap”, containing key
> bindings specific to the buffer.  The minibuffer also has a local keymap
> (*note Intro to Minibuffers::).  If there is a ‘local-map’ text or
> overlay property at point, that specifies the local keymap to use, in
> place of the buffer's default local keymap.
> 
> ‘minor-mode-overriding-map-alist` should have higher priority than the buffer local keymap.
> However, the actual behavior is different than what the docs say.
> 
> Here is my test:
> 
> ```elisp
> ;;;###autoload
> (defvar-keymap typst-ts-mode-map
> ;; ..
> "RET" #'typst-ts-mode-return)
> 
> (defvar-keymap mk/test-map
> "RET" #'(lambda () (interactive) (message "mk/test-map")))
> 
> ;;;###autoload
> (define-derived-mode typst-ts-mode text-mode "Typst"
> "Major mode for editing Typst, powered by tree-sitter."
> :group 'typst
> :syntax-table typst-ts-mode-syntax-table
> :after-hook
> (typst-ts-mode-after-hook-function)
> 
> (setq minor-mode-overriding-map-alist '((outline-minor-mode . nil)))
> (setcdr (assq #'outline-minor-mode minor-mode-overriding-map-alist) mk/test-map)
> 
> ;; ...
> )
> ```
> In this situation, `typst-ts-mode-return` will be executed. 
> 
> If we execute this elisp code and then re-enter `typst-ts-mode`
> ```elisp 
> (keymap-set outline-minor-mode-map "<return>" #'(lambda () (interactive) (message "outline-minor-mode-map")))
> ```
> it will still execute `typst-ts-mode-return` function.
> 
> However, in addition of the previous code, if we then remove the following code in `typst-ts-mode` setup process:
> ```elisp
> (setq minor-mode-overriding-map-alist '((outline-minor-mode . nil)))
> (setcdr (assq #'outline-minor-mode minor-mode-overriding-map-alist) mk/test-map)
> ```
> then the lambda function in `outline-minor-mode-map` will be executed. 

Stefan, any comments or suggestions?