bug#74404: [PATCH] Give Completion Preview bindings higher precedence

bug#74404: [PATCH] Give Completion Preview bindings higher precedence

[Eshel Yaron via Bug reports for GNU Emacs, the Swiss army knife of text editors]

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Tags: patch

Whenever Completion Preview mode shows a completion preview, it also
activates keybindings for commands that interact with that preview, most
notably TAB is bound to completion-preview-insert, which inserts the
suggested completion.  This is implemented via a minor mode
completion-preview-active-mode whose keymap provides these bindings, and
which is enabled when the preview is displayed. 

This all works well, except for when another minor mode, foo-mode, is
enabled, whose keybindings conflict with these active preview bindings.
If foo-mode is defined after completion-preview-active-mode, i.e. if
foo.el is loaded after completion-preview.el, then foo-mode comes first
in minor-mode-map-alist and takes precedence over the bindings in
completion-preview-active-mode-map.

This happens, for example, with eshell-cmpl-mode, a minor mode that is
enabled by default in Eshell, which binds TAB to completion-at-point.
So currently Completion Preview mode doesn't work as expected in Eshell:
when you try to accept the suggested completion (with TAB), you get
completion-at-point instead of completion-preview-insert.

To fix this issue, we need to give the active completion preview
bindings higher precedence than keymaps of minor modes that where
defined after loading completion-preview.el.  The patch below does that
by using minor-mode-overriding-map-alist.  Any thoughts?


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From 951df80d3749b2e82072f397dd7c7b5ce256f36d Mon Sep 17 00:00:00 2001
From: Eshel Yaron <me@eshelyaron.com>
Date: Sun, 17 Nov 2024 16:55:30 +0100
Subject: [PATCH] Give Completion Preview bindings higher precedence

* lisp/completion-preview.el
(completion-preview-active-mode): add keymap to
'minor-mode-overriding-map-alist' so it takes precedence
over other minor mode maps that bind TAB, such as
'eshell-cmpl-mode' in Eshell.
---
 lisp/completion-preview.el | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lisp/completion-preview.el b/lisp/completion-preview.el
index 4564812e8a9..e5be3197032 100644
--- a/lisp/completion-preview.el
+++ b/lisp/completion-preview.el
@@ -322,8 +322,13 @@ completion-preview-active-mode
   "Mode for when the completion preview is shown."
   :interactive nil
   (if completion-preview-active-mode
-      (add-hook 'window-selection-change-functions
-                #'completion-preview--window-selection-change nil t)
+      (progn
+        (add-hook 'window-selection-change-functions
+                  #'completion-preview--window-selection-change nil t)
+        ;; Give keymap precedence over other minor mode maps.
+        (setf (alist-get 'completion-preview-active-mode
+                         minor-mode-overriding-map-alist)
+              completion-preview-active-mode-map))
     (remove-hook 'window-selection-change-functions
                  #'completion-preview--window-selection-change t)
     (completion-preview-hide)))
-- 
2.46.2

bug#74404: [PATCH] Give Completion Preview bindings higher precedence

[Eli Zaretskii]

> Date: Sun, 17 Nov 2024 17:30:47 +0100
> From:  Eshel Yaron via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Whenever Completion Preview mode shows a completion preview, it also
> activates keybindings for commands that interact with that preview, most
> notably TAB is bound to completion-preview-insert, which inserts the
> suggested completion.  This is implemented via a minor mode
> completion-preview-active-mode whose keymap provides these bindings, and
> which is enabled when the preview is displayed. 
> 
> This all works well, except for when another minor mode, foo-mode, is
> enabled, whose keybindings conflict with these active preview bindings.
> If foo-mode is defined after completion-preview-active-mode, i.e. if
> foo.el is loaded after completion-preview.el, then foo-mode comes first
> in minor-mode-map-alist and takes precedence over the bindings in
> completion-preview-active-mode-map.
> 
> This happens, for example, with eshell-cmpl-mode, a minor mode that is
> enabled by default in Eshell, which binds TAB to completion-at-point.
> So currently Completion Preview mode doesn't work as expected in Eshell:
> when you try to accept the suggested completion (with TAB), you get
> completion-at-point instead of completion-preview-insert.
> 
> To fix this issue, we need to give the active completion preview
> bindings higher precedence than keymaps of minor modes that where
> defined after loading completion-preview.el.  The patch below does that
> by using minor-mode-overriding-map-alist.  Any thoughts?

Can't you instead use the 'keymap' text or overlay property?  That
would avoid the "arms race" of precedences.

Adding Stefan, in case he has comments or suggestions.

bug#74404: [PATCH] Give Completion Preview bindings higher precedence

[Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors]

>> To fix this issue, we need to give the active completion preview
>> bindings higher precedence than keymaps of minor modes that where
>> defined after loading completion-preview.el.  The patch below does that
>> by using minor-mode-overriding-map-alist.  Any thoughts?
>
> Can't you instead use the 'keymap' text or overlay property?  That
> would avoid the "arms race" of precedences.
>
> Adding Stefan, in case he has comments or suggestions.

Assuming the minor mode is disabled as soon as point moves away from the
completion, I wouldn't have a clear preference between `keymap` and
`minor-mode-overriding-map-alist`.

BTW, maybe we should add some notion of minor mode precedence since such
problems are actually fairly common.  We could do something similar to
what we do with `add-hook`, so `add-minor-mode` takes care of obeying
the ordering constraints.


        Stefan

bug#74404: [PATCH] Give Completion Preview bindings higher precedence

[Eshel Yaron via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Hi,

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>>> To fix this issue, we need to give the active completion preview
>>> bindings higher precedence than keymaps of minor modes that where
>>> defined after loading completion-preview.el.  The patch below does that
>>> by using minor-mode-overriding-map-alist.  Any thoughts?
>>
>> Can't you instead use the 'keymap' text or overlay property?  That
>> would avoid the "arms race" of precedences.

I thought about that, but no, we can't easily use that, since the
overlay is not necessarily at point: it is generally at the end of the
symbol, and point may be at the middle of the symbol.

>> Adding Stefan, in case he has comments or suggestions.
>
> Assuming the minor mode is disabled as soon as point moves away from the
> completion, I wouldn't have a clear preference between `keymap` and
> `minor-mode-overriding-map-alist`.

Indeed, the minor mode is disabled as soon as the completion preview is
dismissed for whatever reason, including moving point elsewhere.

> BTW, maybe we should add some notion of minor mode precedence since such
> problems are actually fairly common.  We could do something similar to
> what we do with `add-hook`, so `add-minor-mode` takes care of obeying
> the ordering constraints.

That'd be nice, I think.


Thanks,

Eshel

bug#74404: [PATCH] Give Completion Preview bindings higher precedence

[Sean Whitton]

Hello,

On Sun 17 Nov 2024 at 12:16pm -05, Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of text editors" wrote:

> BTW, maybe we should add some notion of minor mode precedence since such
> problems are actually fairly common.  We could do something similar to
> what we do with `add-hook`, so `add-minor-mode` takes care of obeying
> the ordering constraints.

We could also have a customisation option that allows the user to
override the default priorities.  As minor modes are always interned
symbols, this would be possible in a way that it isn't for hook
priorities.

-- 
Sean Whitton

bug#74404: [PATCH] Give Completion Preview bindings higher precedence

[Eshel Yaron via Bug reports for GNU Emacs, the Swiss army knife of text editors]

close 74492 31.1
quit

Hi,

Sean Whitton <spwhitton@spwhitton.name> writes:

> Hello,
>
> On Sun 17 Nov 2024 at 12:16pm -05, Stefan Monnier via "Bug reports for
> GNU Emacs, the Swiss army knife of text editors" wrote:
>
>> BTW, maybe we should add some notion of minor mode precedence since such
>> problems are actually fairly common.  We could do something similar to
>> what we do with `add-hook`, so `add-minor-mode` takes care of obeying
>> the ordering constraints.
>
> We could also have a customisation option that allows the user to
> override the default priorities.  As minor modes are always interned
> symbols, this would be possible in a way that it isn't for hook
> priorities.

I've opened bug#74492 to discuss this broader topic of explicit minor
mode precedence.  For now, I've pushed my patch solving this particular
issue with Completion Preview mode to master (commit 30bcba27c8c).

With that, I'm closing this bug.


Thanks,

Eshel