GNU bug report logs - #77649
[PATCH] Add support for updating *Completions* as you type

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Spencer Baugh <sbaugh <at> janestreet.com>
To: bug-gnu-emacs <at> gnu.org
Subject: [PATCH] Add support for updating *Completions* as you type
Date: Tue, 08 Apr 2025 11:17:17 -0400

[Message part 1 (text/plain, inline)]

Tags: patch


Add support for updating the *Completions* buffer as you type,
controlled by a new completion metadata symbol 'eager-update and
new defcustom completion-eager-update.

You can configure a completion category to update *Completions*
as you type by setting completion-category-overrides
appropriately; or set completion-eager-update to t to always
update *Completions* as you type.

This is similar to the recently added completion-eager-display.

In GNU Emacs 30.1.50 (build 2, x86_64-pc-linux-gnu, X toolkit, cairo
 version 1.15.12, Xaw scroll bars) of 2025-04-03 built on
 igm-qws-u22796a
Repository revision: e0d429965010d82a05225e53ba6fbb97bea23ae9
Repository branch: emacs-30
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description: Rocky Linux 8.10 (Green Obsidian)

Configured using:
 'configure --config-cache --with-x-toolkit=lucid --without-gpm
 --without-gconf --without-selinux --without-imagemagick --with-modules
 --with-gif=no --with-cairo --with-rsvg --without-compress-install
 --with-tree-sitter --with-native-compilation=aot'

[0001-Add-support-for-updating-Completions-as-you-type.patch (text/patch, attachment)]

Message #8 received at 77649 <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> linkov.net>
To: Spencer Baugh <sbaugh <at> janestreet.com>
Cc: Daniel Mendler <mail <at> daniel-mendler.de>, 77649 <at> debbugs.gnu.org
Subject: Re: bug#77649: [PATCH] Add support for updating *Completions* as
 you type
Date: Tue, 08 Apr 2025 21:33:31 +0300

> Add support for updating the *Completions* buffer as you type,
> controlled by a new completion metadata symbol 'eager-update and
> new defcustom completion-eager-update.
>
> You can configure a completion category to update *Completions*
> as you type by setting completion-category-overrides
> appropriately; or set completion-eager-update to t to always
> update *Completions* as you type.
>
> This is similar to the recently added completion-eager-display.

Thanks, now finally we'll have this long-needed feature.

The first question: should it depend on the value of
'minibuffer-visible-completions'?  OTOH, even when it's nil,
*Completions* can be displayed by non-nil completion-eager-display.

So the only problem is that when the *Completions* window is removed
(e.g. when no candidates remains), it never comes back to the display
(e.g. after deleting previous characters).

Or maybe this is not a problem, I have to test it more.

Message #11 received at 77649 <at> debbugs.gnu.org (full text, mbox):

From: Spencer Baugh <sbaugh <at> janestreet.com>
To: Juri Linkov <juri <at> linkov.net>
Cc: Daniel Mendler <mail <at> daniel-mendler.de>, 77649 <at> debbugs.gnu.org
Subject: Re: bug#77649: [PATCH] Add support for updating *Completions* as
 you type
Date: Tue, 08 Apr 2025 15:00:35 -0400

Juri Linkov <juri <at> linkov.net> writes:

>> Add support for updating the *Completions* buffer as you type,
>> controlled by a new completion metadata symbol 'eager-update and
>> new defcustom completion-eager-update.
>>
>> You can configure a completion category to update *Completions*
>> as you type by setting completion-category-overrides
>> appropriately; or set completion-eager-update to t to always
>> update *Completions* as you type.
>>
>> This is similar to the recently added completion-eager-display.
>
> Thanks, now finally we'll have this long-needed feature.

Indeed.  BTW, I should have mentioned in my first email that this
depends, for performance, on the new lazy-inserting-into-*Completions*
functionality I added; that makes performance good even when there are
many completions.

> The first question: should it depend on the value of
> 'minibuffer-visible-completions'?  OTOH, even when it's nil,
> *Completions* can be displayed by non-nil completion-eager-display.

Right, or of course the user could just explicitly hit ? to display
*Completions*.  So I don't currently see a reason why we'd depend on
minibuffer-visible-completions.

> So the only problem is that when the *Completions* window is removed
> (e.g. when no candidates remains), it never comes back to the display
> (e.g. after deleting previous characters).
>
> Or maybe this is not a problem, I have to test it more.

The specific scenario of *Completions* disappearing when no candidates
remain has not been a problem for me.

But it is possible that we want to make other changes in this area
(maybe separate from this patch?)  *Completions* can be hidden for many
reasons, but maybe when eager-display behavior is enabled, *Completions*
should not be hidden as readily?  Maybe eager-display should cause the
behavior to be more like completion-auto-help=visible?

Message #14 received at 77649 <at> debbugs.gnu.org (full text, mbox):

From: sbaugh <at> catern.com
To: Spencer Baugh <sbaugh <at> janestreet.com>
Cc: Daniel Mendler <mail <at> daniel-mendler.de>, 77649 <at> debbugs.gnu.org,
 Juri Linkov <juri <at> linkov.net>
Subject: Re: bug#77649: [PATCH] Add support for updating *Completions* as you
 type
Date: Thu, 17 Jul 2025 20:33:28 +0000 (UTC)

Spencer Baugh <sbaugh <at> janestreet.com> writes:

> Juri Linkov <juri <at> linkov.net> writes:
>
>>> Add support for updating the *Completions* buffer as you type,
>>> controlled by a new completion metadata symbol 'eager-update and
>>> new defcustom completion-eager-update.
>>>
>>> You can configure a completion category to update *Completions*
>>> as you type by setting completion-category-overrides
>>> appropriately; or set completion-eager-update to t to always
>>> update *Completions* as you type.
>>>
>>> This is similar to the recently added completion-eager-display.
>>
>> Thanks, now finally we'll have this long-needed feature.

Hi, have you gotten a chance to try this out?

I have been running this for several completion categories at my site
and have had no complaints.

Message #17 received at 77649 <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> linkov.net>
To: sbaugh <at> catern.com
Cc: Spencer Baugh <sbaugh <at> janestreet.com>, 77649 <at> debbugs.gnu.org,
 Daniel Mendler <mail <at> daniel-mendler.de>
Subject: Re: bug#77649: [PATCH] Add support for updating *Completions* as
 you type
Date: Fri, 18 Jul 2025 09:40:36 +0300

>>>> Add support for updating the *Completions* buffer as you type,
>>>> controlled by a new completion metadata symbol 'eager-update and
>>>> new defcustom completion-eager-update.
>>>>
>>>> You can configure a completion category to update *Completions*
>>>> as you type by setting completion-category-overrides
>>>> appropriately; or set completion-eager-update to t to always
>>>> update *Completions* as you type.
>>>>
>>>> This is similar to the recently added completion-eager-display.
>>>
>>> Thanks, now finally we'll have this long-needed feature.
>
> Hi, have you gotten a chance to try this out?

Yes, I tried it out, and everything worked nicely.

> I have been running this for several completion categories at my site
> and have had no complaints.

Could you send a complete patch with a NEWS entry?

Message #20 received at 77649 <at> debbugs.gnu.org (full text, mbox):

From: Spencer Baugh <sbaugh <at> janestreet.com>
To: Juri Linkov <juri <at> linkov.net>
Cc: sbaugh <at> catern.com, 77649 <at> debbugs.gnu.org,
 Daniel Mendler <mail <at> daniel-mendler.de>
Subject: Re: bug#77649: [PATCH] Add support for updating *Completions* as
 you type
Date: Mon, 21 Jul 2025 12:43:56 -0400

[Message part 1 (text/plain, inline)]

Juri Linkov <juri <at> linkov.net> writes:

>>>>> Add support for updating the *Completions* buffer as you type,
>>>>> controlled by a new completion metadata symbol 'eager-update and
>>>>> new defcustom completion-eager-update.
>>>>>
>>>>> You can configure a completion category to update *Completions*
>>>>> as you type by setting completion-category-overrides
>>>>> appropriately; or set completion-eager-update to t to always
>>>>> update *Completions* as you type.
>>>>>
>>>>> This is similar to the recently added completion-eager-display.
>>>>
>>>> Thanks, now finally we'll have this long-needed feature.
>>
>> Hi, have you gotten a chance to try this out?
>
> Yes, I tried it out, and everything worked nicely.
>
>> I have been running this for several completion categories at my site
>> and have had no complaints.
>
> Could you send a complete patch with a NEWS entry?

Yes, attached.

[0001-Add-support-for-updating-Completions-as-you-type.patch (text/x-patch, inline)]

From 5c8290de611710c1859c65c37daf961507b20e62 Mon Sep 17 00:00:00 2001
From: Spencer Baugh <sbaugh <at> janestreet.com>
Date: Thu, 3 Apr 2025 15:38:22 -0400
Subject: [PATCH] Add support for updating *Completions* as you type

Add support for updating the *Completions* buffer as you type,
controlled by a new completion metadata symbol 'eager-update and
new defcustom completion-eager-update.

You can configure a completion category to update *Completions*
as you type by setting completion-category-overrides
appropriately; or set completion-eager-update to t to always
update *Completions* as you type.

This is similar to the recently added completion-eager-display.

* lisp/minibuffer.el (completion-eager-update): Add new
defcustom defaulting to 'auto. (bug#77649)
(completion--eager-update-p, completions--background-update)
(completions--post-command-update): Add.
(completions--after-change): Call
completions--post-command-update via post-command-hook.
(minibuffer-completion-help): Check completion-eager-update and
install completions--after-change.
(completion-help-at-point): Call completion--eager-update-p if
ONLY-IF-EAGER is non-nil.
* etc/NEWS: Announce completion-eager-update.  Slightly reword the
announcement of completion-eager-display for consistency.
---
 etc/NEWS           | 13 +++++++++-
 lisp/minibuffer.el | 59 +++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 65 insertions(+), 7 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index b469b22aacf..0c0f333319a 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -167,11 +167,22 @@ This option configures whether completion commands should display the
 "*Completions*" buffer immediately.  When the option is set to t, all
 completion commands show "*Completions*" immediately, respectively nil
 disables the eager display for all commands.  The default setting auto
-enables eager completion only if requested by the command.
+enables eager display only if requested by the command.
 For more fine-grained control you can also toggle this feature by
 category using the symbol 'eager-display' in the user option
 'completion-category-overrides'.
 
++++
+*** New user option 'completion-eager-update.
+This option configures whether typing should update the contents of the
+"*Completions*" buffer, if it is shown.  When the option is set to t,
+typing will always update the "*Completions*" buffer.  Note that for
+large or inefficient completion tables, this can slow down typing.  The
+default setting enables eager updating only if requested by the command.
+For more fine-grained control you can also toggle this feature by
+category using the symbol 'eager-update in the user option
+'completion-category-overrides'.
+
 +++
 *** New user option 'completion-pcm-leading-wildcard'.
 This option configures how the partial-completion style does completion.
diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
index 571c4174537..12f66f57747 100644
--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -1072,6 +1072,21 @@ completion-eager-display
                  (const :tag "If requested by the completion command" auto))
   :version "31.1")
 
+(defcustom completion-eager-update 'auto
+  "Whether typing should update the *Completions* buffer eagerly.
+
+If `t', always update as you type.
+
+If `auto', only update if the completion table has requested it or
+`eager-update' is set in in `completion-category-defaults'.
+
+This only affects the *Completions* buffer if it is already
+displayed."
+  :type '(choice (const :tag "Do nothing when you type" nil)
+                 (const :tag "Auto-update based on the category" auto)
+                 (const :tag "Always update as you type" t))
+  :version "31.1")
+
 (defcustom completion-auto-help t
   "Non-nil means automatically provide help for invalid completion input.
 If the value is t, the *Completions* buffer is displayed whenever completion
@@ -2648,12 +2663,43 @@ completions--deselect
     (goto-char (or (next-single-property-change (point) 'completion--string)
                    (point-max)))))
 
+(defun completion--eager-update-p (start)
+  "Return non-nil if *Completions* should be automatically updated.
+
+If `completion-eager-update' is the symbol `auto', checks completion
+metadata for the string from START to point."
+  (if (eq completion-eager-update 'auto)
+      (completion-metadata-get (completion--field-metadata start) 'eager-update)
+    completion-eager-update))
+
+(defun completions--background-update ()
+  "Try to update *Completions* without blocking input.
+
+This function uses `while-no-input' and sets `non-essential' to t
+so that the update is less likely to interfere with user typing."
+  (while-no-input
+    (let ((non-essential t))
+      (redisplay)
+      (cond
+       (completion-in-region-mode (completion-help-at-point t))
+       ((completion--eager-update-p (minibuffer-prompt-end))
+        (minibuffer-completion-help))))))
+
+(defun completions--post-command-update ()
+  "Update displayed *Completions* buffer after command, once."
+  (remove-hook 'post-command-hook #'completions--post-command-update)
+  (when (and completion-eager-update (get-buffer-window "*Completions*" 0))
+    (completions--background-update)))
+
 (defun completions--after-change (_start _end _old-len)
   "Update displayed *Completions* buffer after change in buffer contents."
-  (when completion-auto-deselect
+  (when (or completion-auto-deselect completion-eager-update)
     (when-let* ((window (get-buffer-window "*Completions*" 0)))
-      (with-selected-window window
-        (completions--deselect)))))
+      (when completion-auto-deselect
+        (with-selected-window window
+          (completions--deselect)))
+      (when completion-eager-update
+        (add-hook 'post-command-hook #'completions--post-command-update)))))
 
 (defun minibuffer-completion-help (&optional start end)
   "Display a list of possible completions of the current minibuffer contents."
@@ -2744,7 +2790,7 @@ minibuffer-completion-help
             (body-function
              . ,#'(lambda (window)
                     (with-current-buffer mainbuf
-                      (when completion-auto-deselect
+                      (when (or completion-auto-deselect completion-eager-update)
                         (add-hook 'after-change-functions #'completions--after-change nil t))
                       ;; Remove the base-size tail because `sort' requires a properly
                       ;; nil-terminated list.
@@ -3133,7 +3179,7 @@ completion-at-point
                   (car res)))
        (cdr res)))))
 
-(defun completion-help-at-point ()
+(defun completion-help-at-point (&optional only-if-eager)
   "Display the completions on the text around point.
 The completion method is determined by `completion-at-point-functions'."
   (interactive)
@@ -3160,7 +3206,8 @@ completion-help-at-point
                `(,start ,(copy-marker end t) ,collection
                         ,(plist-get plist :predicate)))
          (completion-in-region-mode 1)
-         (minibuffer-completion-help start end)))
+         (when (or (not only-if-eager) (completion--eager-update-p start))
+           (minibuffer-completion-help start end))))
       (`(,hookfun . ,_)
        ;; The hook function already performed completion :-(
        ;; Not much we can do at this point.
-- 
2.39.3

Message #23 received at 77649 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Spencer Baugh <sbaugh <at> janestreet.com>
Cc: sbaugh <at> catern.com, 77649 <at> debbugs.gnu.org, mail <at> daniel-mendler.de,
 juri <at> linkov.net
Subject: Re: bug#77649: [PATCH] Add support for updating *Completions* as you
 type
Date: Tue, 22 Jul 2025 15:22:34 +0300

> Cc: sbaugh <at> catern.com, 77649 <at> debbugs.gnu.org,
>  Daniel Mendler <mail <at> daniel-mendler.de>
> Date: Mon, 21 Jul 2025 12:43:56 -0400
> From:  Spencer Baugh via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs <at> gnu.org>
> 
> +*** New user option 'completion-eager-update.
                                               ^
Closing quote missing there.

> +This option configures whether typing should update the contents of the
               ^^^^^^^^^^
We normally use "controls".

> +"*Completions*" buffer, if it is shown.  When the option is set to t,
> +typing will always update the "*Completions*" buffer.  Note that for
> +large or inefficient completion tables, this can slow down typing.  The
> +default setting enables eager updating only if requested by the command.
> +For more fine-grained control you can also toggle this feature by
> +category using the symbol 'eager-update in the user option
> +'completion-category-overrides'.

IMO, the last two sentences are too vague/mysterious to be useful
(this is a user option, remember?)

> +If `auto', only update if the completion table has requested it or
> +`eager-update' is set in in `completion-category-defaults'.

This should at least hint how would a completion table request the
update, or mention some function or variable whose doc string explains
that.

The doc string should also describe what happens when the value is nil.

> +  :type '(choice (const :tag "Do nothing when you type" nil)

"Do nothing" is incorrect.  I think you mean "Do not update
completions" or somesuch.

Thanks.

Message #26 received at 77649 <at> debbugs.gnu.org (full text, mbox):

From: Spencer Baugh <sbaugh <at> janestreet.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: sbaugh <at> catern.com, 77649 <at> debbugs.gnu.org, juri <at> linkov.net,
 mail <at> daniel-mendler.de
Subject: Re: bug#77649: [PATCH] Add support for updating *Completions* as
 you type
Date: Tue, 22 Jul 2025 12:32:18 -0400

Eli Zaretskii <eliz <at> gnu.org> writes:

>> Cc: sbaugh <at> catern.com, 77649 <at> debbugs.gnu.org,
>>  Daniel Mendler <mail <at> daniel-mendler.de>
>> Date: Mon, 21 Jul 2025 12:43:56 -0400
>> From:  Spencer Baugh via "Bug reports for GNU Emacs,
>>  the Swiss army knife of text editors" <bug-gnu-emacs <at> gnu.org>
>> 
>> +*** New user option 'completion-eager-update.
>                                                ^
> Closing quote missing there.
>
>> +This option configures whether typing should update the contents of the
>                ^^^^^^^^^^
> We normally use "controls".
>
>> +"*Completions*" buffer, if it is shown.  When the option is set to t,
>> +typing will always update the "*Completions*" buffer.  Note that for
>> +large or inefficient completion tables, this can slow down typing.  The
>> +default setting enables eager updating only if requested by the command.
>> +For more fine-grained control you can also toggle this feature by
>> +category using the symbol 'eager-update in the user option
>> +'completion-category-overrides'.
>
> IMO, the last two sentences are too vague/mysterious to be useful
> (this is a user option, remember?)

These two sentences are just copied (with a minor change) from the
announcement for the very similar option completion-eager-display, just
above.  Should I reword that one as well in this commit?

>> +If `auto', only update if the completion table has requested it or
>> +`eager-update' is set in in `completion-category-defaults'.
>
> This should at least hint how would a completion table request the
> update, or mention some function or variable whose doc string explains
> that.
>
> The doc string should also describe what happens when the value is nil.
>
>> +  :type '(choice (const :tag "Do nothing when you type" nil)
>
> "Do nothing" is incorrect.  I think you mean "Do not update
> completions" or somesuch.
>
> Thanks.

Message #29 received at 77649 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Spencer Baugh <sbaugh <at> janestreet.com>
Cc: sbaugh <at> catern.com, 77649 <at> debbugs.gnu.org, juri <at> linkov.net,
 mail <at> daniel-mendler.de
Subject: Re: bug#77649: [PATCH] Add support for updating *Completions* as
 you type
Date: Tue, 22 Jul 2025 20:05:04 +0300

> From: Spencer Baugh <sbaugh <at> janestreet.com>
> Cc: sbaugh <at> catern.com,  77649 <at> debbugs.gnu.org,  mail <at> daniel-mendler.de,
>    juri <at> linkov.net
> Date: Tue, 22 Jul 2025 12:32:18 -0400
> 
> Eli Zaretskii <eliz <at> gnu.org> writes:
> 
> >> Cc: sbaugh <at> catern.com, 77649 <at> debbugs.gnu.org,
> >>  Daniel Mendler <mail <at> daniel-mendler.de>
> >> Date: Mon, 21 Jul 2025 12:43:56 -0400
> >> From:  Spencer Baugh via "Bug reports for GNU Emacs,
> >>  the Swiss army knife of text editors" <bug-gnu-emacs <at> gnu.org>
> >> 
> >> +*** New user option 'completion-eager-update.
> >                                                ^
> > Closing quote missing there.
> >
> >> +This option configures whether typing should update the contents of the
> >                ^^^^^^^^^^
> > We normally use "controls".
> >
> >> +"*Completions*" buffer, if it is shown.  When the option is set to t,
> >> +typing will always update the "*Completions*" buffer.  Note that for
> >> +large or inefficient completion tables, this can slow down typing.  The
> >> +default setting enables eager updating only if requested by the command.
> >> +For more fine-grained control you can also toggle this feature by
> >> +category using the symbol 'eager-update in the user option
> >> +'completion-category-overrides'.
> >
> > IMO, the last two sentences are too vague/mysterious to be useful
> > (this is a user option, remember?)
> 
> These two sentences are just copied (with a minor change) from the
> announcement for the very similar option completion-eager-display, just
> above.  Should I reword that one as well in this commit?

If you wish, yes.

Message #32 received at 77649 <at> debbugs.gnu.org (full text, mbox):

From: Spencer Baugh <sbaugh <at> janestreet.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: sbaugh <at> catern.com, 77649 <at> debbugs.gnu.org, mail <at> daniel-mendler.de,
 juri <at> linkov.net
Subject: Re: bug#77649: [PATCH] Add support for updating *Completions* as
 you type
Date: Tue, 22 Jul 2025 15:27:53 -0400

[Message part 1 (text/plain, inline)]

Eli Zaretskii <eliz <at> gnu.org> writes:
>> From: Spencer Baugh <sbaugh <at> janestreet.com>
>> Cc: sbaugh <at> catern.com,  77649 <at> debbugs.gnu.org,  mail <at> daniel-mendler.de,
>>    juri <at> linkov.net
>> Date: Tue, 22 Jul 2025 12:32:18 -0400
>> 
>> Eli Zaretskii <eliz <at> gnu.org> writes:
>> 
>> >> Cc: sbaugh <at> catern.com, 77649 <at> debbugs.gnu.org,
>> >>  Daniel Mendler <mail <at> daniel-mendler.de>
>> >> Date: Mon, 21 Jul 2025 12:43:56 -0400
>> >> From:  Spencer Baugh via "Bug reports for GNU Emacs,
>> >>  the Swiss army knife of text editors" <bug-gnu-emacs <at> gnu.org>
>> >> 
>> >> +*** New user option 'completion-eager-update.
>> >                                                ^
>> > Closing quote missing there.
>> >
>> >> +This option configures whether typing should update the contents of the
>> >                ^^^^^^^^^^
>> > We normally use "controls".
>> >
>> >> +"*Completions*" buffer, if it is shown.  When the option is set to t,
>> >> +typing will always update the "*Completions*" buffer.  Note that for
>> >> +large or inefficient completion tables, this can slow down typing.  The
>> >> +default setting enables eager updating only if requested by the command.
>> >> +For more fine-grained control you can also toggle this feature by
>> >> +category using the symbol 'eager-update in the user option
>> >> +'completion-category-overrides'.
>> >
>> > IMO, the last two sentences are too vague/mysterious to be useful
>> > (this is a user option, remember?)
>> 
>> These two sentences are just copied (with a minor change) from the
>> announcement for the very similar option completion-eager-display, just
>> above.  Should I reword that one as well in this commit?
>
> If you wish, yes.

Updated and fixed your feedback.

[0001-Add-support-for-updating-Completions-as-you-type.patch (text/x-patch, inline)]

From 6e6d38974ad142882fd9919f452ae311b418a712 Mon Sep 17 00:00:00 2001
From: Spencer Baugh <sbaugh <at> janestreet.com>
Date: Thu, 3 Apr 2025 15:38:22 -0400
Subject: [PATCH] Add support for updating *Completions* as you type

Add support for updating the *Completions* buffer as you type,
controlled by a new completion metadata symbol 'eager-update and
new defcustom completion-eager-update.

You can configure a completion category to update *Completions*
as you type by setting completion-category-overrides
appropriately; or set completion-eager-update to t to always
update *Completions* as you type.

This is similar to the recently added completion-eager-display.

* lisp/minibuffer.el (completion-eager-update): Add new
defcustom defaulting to 'auto. (bug#77649)
(completion--eager-update-p, completions--background-update)
(completions--post-command-update): Add.
(completions--after-change): Call
completions--post-command-update via post-command-hook.
(minibuffer-completion-help): Check completion-eager-update and
install completions--after-change.
(completion-help-at-point): Call completion--eager-update-p if
ONLY-IF-EAGER is non-nil.
* etc/NEWS: Announce completion-eager-update.  Reword the
announcement of completion-eager-display for consistency.
---
 etc/NEWS           | 29 +++++++++++++++-------
 lisp/minibuffer.el | 62 +++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 76 insertions(+), 15 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index 2d904614153..f2a08ee3009 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -173,15 +173,26 @@ this behavior is now off by default.  You can re-enable it by setting
 ** Minibuffer and Completions
 
 +++
-*** New user option 'completion-eager-display'.
-This option configures whether completion commands should display the
-"*Completions*" buffer immediately.  When the option is set to t, all
-completion commands show "*Completions*" immediately, respectively nil
-disables the eager display for all commands.  The default setting auto
-enables eager completion only if requested by the command.
-For more fine-grained control you can also toggle this feature by
-category using the symbol 'eager-display' in the user option
-'completion-category-overrides'.
+*** Support for immediate display of the "*Completions*" buffer
+Whenever a minibuffer with completion is opened, the "*Completions*"
+buffer will now be displayed immediately if the completion property
+'eager-display', set by the completion table, is non-nil.  This property
+can be overridden for different completion categories by customizing
+'completion-category-overrides'.  Alternatively, the new user option
+'completion-eager-display' can be set to t to force eager display of
+"*Completions*" for all minibuffers, or nil to suppress this for all
+minibuffers.
+
++++
+*** Support for updating "*Completions*" as you type
+If the "*Completions*" buffer is displayed, it will now be updated as
+you type if the completion property 'eager-update', set by the
+completion table, is non-nil.  This property can be overridden for
+different completion categories by customizing
+'completion-category-overrides'.  Alternatively, the new user option
+'completion-eager-update can be set to t to make "*Completions*" always
+be updated as you type, or nil to suppress this always.  Note that for
+large or inefficient completion tables this can slow down typing.
 
 +++
 *** New user option 'completion-pcm-leading-wildcard'.
diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
index 571c4174537..ea2546f7d2c 100644
--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -1072,6 +1072,24 @@ completion-eager-display
                  (const :tag "If requested by the completion command" auto))
   :version "31.1")
 
+(defcustom completion-eager-update 'auto
+  "Whether the *Completions* buffer should update as you type.
+
+If `t', always update as you type.
+
+If `auto', only update if the completion property 'eager-update' is
+non-nil, whether set by the completion table or by
+`completion-category-overrides' or by `completion-category-defaults'.
+
+If nil, never update as you type.
+
+This only affects the *Completions* buffer if it is already
+displayed."
+  :type '(choice (const :tag "Don't update as you type" nil)
+                 (const :tag "Auto-update based on the category" auto)
+                 (const :tag "Always update as you type" t))
+  :version "31.1")
+
 (defcustom completion-auto-help t
   "Non-nil means automatically provide help for invalid completion input.
 If the value is t, the *Completions* buffer is displayed whenever completion
@@ -2648,12 +2666,43 @@ completions--deselect
     (goto-char (or (next-single-property-change (point) 'completion--string)
                    (point-max)))))
 
+(defun completion--eager-update-p (start)
+  "Return non-nil if *Completions* should be automatically updated.
+
+If `completion-eager-update' is the symbol `auto', checks completion
+metadata for the string from START to point."
+  (if (eq completion-eager-update 'auto)
+      (completion-metadata-get (completion--field-metadata start) 'eager-update)
+    completion-eager-update))
+
+(defun completions--background-update ()
+  "Try to update *Completions* without blocking input.
+
+This function uses `while-no-input' and sets `non-essential' to t
+so that the update is less likely to interfere with user typing."
+  (while-no-input
+    (let ((non-essential t))
+      (redisplay)
+      (cond
+       (completion-in-region-mode (completion-help-at-point t))
+       ((completion--eager-update-p (minibuffer-prompt-end))
+        (minibuffer-completion-help))))))
+
+(defun completions--post-command-update ()
+  "Update displayed *Completions* buffer after command, once."
+  (remove-hook 'post-command-hook #'completions--post-command-update)
+  (when (and completion-eager-update (get-buffer-window "*Completions*" 0))
+    (completions--background-update)))
+
 (defun completions--after-change (_start _end _old-len)
   "Update displayed *Completions* buffer after change in buffer contents."
-  (when completion-auto-deselect
+  (when (or completion-auto-deselect completion-eager-update)
     (when-let* ((window (get-buffer-window "*Completions*" 0)))
-      (with-selected-window window
-        (completions--deselect)))))
+      (when completion-auto-deselect
+        (with-selected-window window
+          (completions--deselect)))
+      (when completion-eager-update
+        (add-hook 'post-command-hook #'completions--post-command-update)))))
 
 (defun minibuffer-completion-help (&optional start end)
   "Display a list of possible completions of the current minibuffer contents."
@@ -2744,7 +2793,7 @@ minibuffer-completion-help
             (body-function
              . ,#'(lambda (window)
                     (with-current-buffer mainbuf
-                      (when completion-auto-deselect
+                      (when (or completion-auto-deselect completion-eager-update)
                         (add-hook 'after-change-functions #'completions--after-change nil t))
                       ;; Remove the base-size tail because `sort' requires a properly
                       ;; nil-terminated list.
@@ -3133,7 +3182,7 @@ completion-at-point
                   (car res)))
        (cdr res)))))
 
-(defun completion-help-at-point ()
+(defun completion-help-at-point (&optional only-if-eager)
   "Display the completions on the text around point.
 The completion method is determined by `completion-at-point-functions'."
   (interactive)
@@ -3160,7 +3209,8 @@ completion-help-at-point
                `(,start ,(copy-marker end t) ,collection
                         ,(plist-get plist :predicate)))
          (completion-in-region-mode 1)
-         (minibuffer-completion-help start end)))
+         (when (or (not only-if-eager) (completion--eager-update-p start))
+           (minibuffer-completion-help start end))))
       (`(,hookfun . ,_)
        ;; The hook function already performed completion :-(
        ;; Not much we can do at this point.
-- 
2.39.3

Message #35 received at 77649 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Spencer Baugh <sbaugh <at> janestreet.com>
Cc: sbaugh <at> catern.com, 77649 <at> debbugs.gnu.org, mail <at> daniel-mendler.de,
 juri <at> linkov.net
Subject: Re: bug#77649: [PATCH] Add support for updating *Completions* as
 you type
Date: Sat, 26 Jul 2025 12:42:02 +0300

> From: Spencer Baugh <sbaugh <at> janestreet.com>
> Cc: sbaugh <at> catern.com,  77649 <at> debbugs.gnu.org,  juri <at> linkov.net,
>    mail <at> daniel-mendler.de
> Date: Tue, 22 Jul 2025 15:27:53 -0400
> 
> Eli Zaretskii <eliz <at> gnu.org> writes:
> >> From: Spencer Baugh <sbaugh <at> janestreet.com>
> >> Cc: sbaugh <at> catern.com,  77649 <at> debbugs.gnu.org,  mail <at> daniel-mendler.de,
> >>    juri <at> linkov.net
> >> Date: Tue, 22 Jul 2025 12:32:18 -0400
> >> 
> >> Eli Zaretskii <eliz <at> gnu.org> writes:
> >> 
> >> >> Cc: sbaugh <at> catern.com, 77649 <at> debbugs.gnu.org,
> >> >>  Daniel Mendler <mail <at> daniel-mendler.de>
> >> >> Date: Mon, 21 Jul 2025 12:43:56 -0400
> >> >> From:  Spencer Baugh via "Bug reports for GNU Emacs,
> >> >>  the Swiss army knife of text editors" <bug-gnu-emacs <at> gnu.org>
> >> >> 
> >> >> +*** New user option 'completion-eager-update.
> >> >                                                ^
> >> > Closing quote missing there.
> >> >
> >> >> +This option configures whether typing should update the contents of the
> >> >                ^^^^^^^^^^
> >> > We normally use "controls".
> >> >
> >> >> +"*Completions*" buffer, if it is shown.  When the option is set to t,
> >> >> +typing will always update the "*Completions*" buffer.  Note that for
> >> >> +large or inefficient completion tables, this can slow down typing.  The
> >> >> +default setting enables eager updating only if requested by the command.
> >> >> +For more fine-grained control you can also toggle this feature by
> >> >> +category using the symbol 'eager-update in the user option
> >> >> +'completion-category-overrides'.
> >> >
> >> > IMO, the last two sentences are too vague/mysterious to be useful
> >> > (this is a user option, remember?)
> >> 
> >> These two sentences are just copied (with a minor change) from the
> >> announcement for the very similar option completion-eager-display, just
> >> above.  Should I reword that one as well in this commit?
> >
> > If you wish, yes.
> 
> Updated and fixed your feedback.

Thanks.

> +*** Support for immediate display of the "*Completions*" buffer
> +Whenever a minibuffer with completion is opened, the "*Completions*"
> +buffer will now be displayed immediately if the completion property
> +'eager-display', set by the completion table, is non-nil.  This property
> +can be overridden for different completion categories by customizing
> +'completion-category-overrides'.  Alternatively, the new user option
> +'completion-eager-display' can be set to t to force eager display of
> +"*Completions*" for all minibuffers, or nil to suppress this for all
> +minibuffers.
> +
> ++++
> +*** Support for updating "*Completions*" as you type
> +If the "*Completions*" buffer is displayed, it will now be updated as
> +you type if the completion property 'eager-update', set by the
> +completion table, is non-nil.  This property can be overridden for
> +different completion categories by customizing
> +'completion-category-overrides'.  Alternatively, the new user option
> +'completion-eager-update can be set to t to make "*Completions*" always
> +be updated as you type, or nil to suppress this always.  Note that for
> +large or inefficient completion tables this can slow down typing.

The two heading lines still don't end in a period.

No further comments, once those nits are fixed.

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