bug#39564: 28.0.50; read-key function do not display the prompt if called from read-from-minibuffer

bug#39564: 28.0.50; read-key function do not display the prompt if called from read-from-minibuffer

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

read-key function not display the prompt if called from
read-from-minibuffer

In the current emacs master this issue breaks a package like ivy.

This has been discused in: https://github.com/abo-abo/swiper/issues/2444

As a test code provided by the ivy developer Oleh Krehel:

```
(let ((map (make-sparse-keymap)))
   (define-key map (kbd "C-f") (lambda ()
                                 (interactive)
                                 (message "%S" (read-key "line1\nline2\nline3\nTest2: "))
                                 (minibuffer-keyboard-quit)))
   (read-from-minibuffer "Test1: " nil map))
```


In GNU Emacs 28.0.50 (build 22, x86_64-pc-linux-gnu, GTK+ Version 3.24.13, cairo version 1.17.3)
  of 2020-02-07 built on Ergus
Repository revision: 30abcda54e1b0e15fc10b3db1c2b9f89ca521bfa
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bug#39564: 28.0.50; read-key function do not display the prompt if called from read-from-minibuffer

[Eli Zaretskii]

> Date: Tue, 11 Feb 2020 15:49:41 +0100
> From: Ergus via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> read-key function not display the prompt if called from
> read-from-minibuffer
> 
> In the current emacs master this issue breaks a package like ivy.
> 
> This has been discused in: https://github.com/abo-abo/swiper/issues/2444
> 
> As a test code provided by the ivy developer Oleh Krehel:
> 
> ```
> (let ((map (make-sparse-keymap)))
>    (define-key map (kbd "C-f") (lambda ()
>                                  (interactive)
>                                  (message "%S" (read-key "line1\nline2\nline3\nTest2: "))
>                                  (minibuffer-keyboard-quit)))
>    (read-from-minibuffer "Test1: " nil map))
> ```

I tried this, but without instructions how to reproduce the problem, I
cannot be sure I did the required gestures.  Just evaluating the above
in *scratch* and then typing C-f does show the prompt, IIUC what is
meant by that.

So please provide more detailed instructions to reproduce the issue.

Thanks.

bug#39564: 28.0.50; read-key function do not display the prompt if called from read-from-minibuffer

[Oleh Krehel]

Hello,

Here's an updated code that works as intended on 26.3 and unexpected on 28.

(defun make-lines (n)
  (mapconcat #'number-to-string
             (number-sequence 0 n) "\n"))

(let ((map (make-sparse-keymap)))
  (define-key map (kbd "C-f") (lambda ()
                                (interactive)
                                (let ((inhibit-field-text-motion t))
                                  (goto-char (point-min)))
                                (message "%S"
                                         (read-key
                                          (concat
                                           (make-lines 10)
                                           "\nTest2")))
                                (minibuffer-keyboard-quit)))
  (read-from-minibuffer (concat (make-lines 10) "\nTest1: ") nil map))

The idea here is that the read-key hint will occupy as much space as
the initial read-from-minibuffer.

regards,
Oleh

bug#39564: 28.0.50; read-key function do not display the prompt if called from read-from-minibuffer

[Eli Zaretskii]

> From: Oleh Krehel <ohwoeowho@gmail.com>
> Date: Tue, 11 Feb 2020 17:17:02 +0100
> 
> Here's an updated code that works as intended on 26.3 and unexpected on 28.
> 
> (defun make-lines (n)
>   (mapconcat #'number-to-string
>              (number-sequence 0 n) "\n"))
> 
> (let ((map (make-sparse-keymap)))
>   (define-key map (kbd "C-f") (lambda ()
>                                 (interactive)
>                                 (let ((inhibit-field-text-motion t))
>                                   (goto-char (point-min)))
>                                 (message "%S"
>                                          (read-key
>                                           (concat
>                                            (make-lines 10)
>                                            "\nTest2")))
>                                 (minibuffer-keyboard-quit)))
>   (read-from-minibuffer (concat (make-lines 10) "\nTest1: ") nil map))
> 
> The idea here is that the read-key hint will occupy as much space as
> the initial read-from-minibuffer.

Thanks, but I still don't understand what should one do with this
snippet (after evaluating it) to see the problem.  Please tell more.

bug#39564: 28.0.50; read-key function do not display the prompt if called from read-from-minibuffer

[Oleh Krehel]

> Thanks, but I still don't understand what should one do with this
> snippet (after evaluating it) to see the problem.  Please tell more.

Here's the behavior in 26.3: the minibuffer is 10 lines tall for
read-from-minibuffer. I'd like read-key to keep the same window height
as not to distract the user, and to have the whole contents of
read-key hint to take over the 10 lines of the minibuffer. Right now,
on 28, the hint is only partially visible. While the behavior on 26.3
and earlier is exactly what I want.

bug#39564: 28.0.50; read-key function do not display the prompt if called from read-from-minibuffer

[Eli Zaretskii]

> From: Oleh Krehel <ohwoeowho@gmail.com>
> Date: Wed, 12 Feb 2020 14:21:35 +0100
> Cc: 39564@debbugs.gnu.org
> 
> > Thanks, but I still don't understand what should one do with this
> > snippet (after evaluating it) to see the problem.  Please tell more.
> 
> Here's the behavior in 26.3: the minibuffer is 10 lines tall for
> read-from-minibuffer.

Sorry, I still don't understand: are you saying that you get a 10-line
mini-window after just evaluating the code snippet you posted?  If so,
then I cannot reproduce that: I see a 9-line mini-window, both in
Emacs 26.3 and the current emacs-27 branch (Emacs 27.0.60).

Do I need to do anything after evaluating the code you posted?  (I
think I do, because otherwise I don't understand, for example, why you
bind C-f to some function there.)

Thanks.

bug#39564: 28.0.50; read-key function do not display the prompt

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

> Sorry, I still don't understand: are you saying that you get a 10-line
> mini-window after just evaluating the code snippet you posted?  If so,
> then I cannot reproduce that: I see a 9-line mini-window, both in
> Emacs 26.3 and the current emacs-27 branch (Emacs 27.0.60).
> 
> Do I need to do anything after evaluating the code you posted?  (I
> think I do, because otherwise I don't understand, for example, why you
> bind C-f to some function there.)
> 
> Thanks.

I also evaluated the latest code and I get exactly the same behaviour in
emacs 26.3, 27 and 28 (actual master).

bug#39564:

[Matt Kramer]

[-- Attachment #1: Type: text/plain, Size: 802 bytes --]

In my case I *do* get different behavior in emacs -Q between 26.3 and
27.0.60 (75a9eee8b). I had to replace minibuffer-keyboard-quit with
abort-recursive-edit, since the former doesn't exist in 26.3. The initial
minibuffer hint looks the same in both cases:

0
1
2
3
4
5
6
7
8
9
10
Test1:
       ^
       |--- cursor

After pressing C-f, 26.3 gives the expected result:

0
1
2
3
4
5
6
7
8
9
10
Test2
     ^
     |--- cursor

However, 27.0.60 gives me the following bizarre content in the minibuffer
(where did that square bracket come from?):

0
1
2
3
4
5
6
7
8
9
10
Test1:  [0
1
2
3
4

in which the cursor is on the 0 at the very top. The read-key function
appears to be identical between the two revisions, aside from a trivial
change to support tab-bar, so I have no idea where the culprit may lie.

[-- Attachment #2: Type: text/html, Size: 2861 bytes --]

bug#39564:

[Eli Zaretskii]

> From: Matt Kramer <mccleetus@gmail.com>
> Date: Wed, 26 Feb 2020 12:04:25 -0800
> 
> In my case I *do* get different behavior in emacs -Q between 26.3 and 27.0.60 (75a9eee8b). I had to replace
> minibuffer-keyboard-quit with abort-recursive-edit, since the former doesn't exist in 26.3.

Please show the code you used, and please describe the exact sequence
of keys you type to reproduce the problem in Emacs 27.

Thanks.

bug#39564:

[Matt Kramer]

Code I used:

(defun make-lines (n)
  (mapconcat #'number-to-string
             (number-sequence 0 n) "\n"))

(let ((map (make-sparse-keymap)))
  (define-key map (kbd "C-f") (lambda ()
                                (interactive)
                                (let ((inhibit-field-text-motion t))
                                  (goto-char (point-min)))
                                (message "%S"
                                         (read-key
                                          (concat
                                           (make-lines 10)
                                           "\nTest2")))
                                (abort-recursive-edit)))
  (read-from-minibuffer (concat (make-lines 10) "\nTest1: ") nil map))

With this code in the clipboard, I start emacs -Q (again, 27.0.60
commit 75a9eee8b), and immediately hit the following sequence of keys:

C-y
M-x eval-buffer RET
C-f

The eval-buffer results are initially as expected. However, after
hitting C-f, the minibuffer then becomes:

0
1
2
3
4
5
6
7
8
9
10
Test1:  [0
1
2
3
4

with point at the very beginning of the minibuffer (first 0).

bug#39564:

[Eli Zaretskii]

> From: Matt Kramer <mccleetus@gmail.com>
> Date: Fri, 28 Feb 2020 09:33:57 -0800
> 
> Code I used:
> 
> (defun make-lines (n)
>   (mapconcat #'number-to-string
>              (number-sequence 0 n) "\n"))
> 
> (let ((map (make-sparse-keymap)))
>   (define-key map (kbd "C-f") (lambda ()
>                                 (interactive)
>                                 (let ((inhibit-field-text-motion t))
>                                   (goto-char (point-min)))
>                                 (message "%S"
>                                          (read-key
>                                           (concat
>                                            (make-lines 10)
>                                            "\nTest2")))
>                                 (abort-recursive-edit)))
>   (read-from-minibuffer (concat (make-lines 10) "\nTest1: ") nil map))
> 
> With this code in the clipboard, I start emacs -Q (again, 27.0.60
> commit 75a9eee8b), and immediately hit the following sequence of keys:
> 
> C-y
> M-x eval-buffer RET
> C-f
> 
> The eval-buffer results are initially as expected. However, after
> hitting C-f, the minibuffer then becomes:
> 
> 0
> 1
> 2
> 3
> 4
> 5
> 6
> 7
> 8
> 9
> 10
> Test1:  [0
> 1
> 2
> 3
> 4
> 
> with point at the very beginning of the minibuffer (first 0).

Looks like the intended behavior for this code: the "[0 ..." part is
the text of the message displayed by the command bound to C-f; it is
enclosed in brackets to indicate that it is a message text separate
from the rest of the prompt.  This display of echo-area messages that
attempts not to overwrite the minibuffer prompt in an active
minibuffer is a new feature of Emacs 27.  By default, Emacs will not
let the mini-window grow enough to show the entire combined text of
the prompt and the message, but if you set max-mini-window-height to a
value 22 or greater, you will see this:

  0
  1
  2
  3
  4
  5
  6
  7
  8
  9
  10
  Test1:  [0
  1
  2
  3
  4
  5
  6
  7
  8
  9
  10
  Test2]

which is what I would expect, given the code you presented.

Going back to the original report, what is the bug here?

Thanks.

bug#39564:

[Matt Kramer]

Thanks Eli for the explanation. Sorry for the trouble. It looks like
Ivy (at least, in ivy-dispatching-done) assumes the old behavior, to
wit, that echo-area messages will overwrite the minibuffer prompt,
leading to the regression discussed in
https://github.com/abo-abo/swiper/issues/2444. The conversation will
continue over there, I guess.

On Sat, Feb 29, 2020 at 12:17 AM Eli Zaretskii <eliz@gnu.org> wrote:
>
> > From: Matt Kramer <mccleetus@gmail.com>
> > Date: Fri, 28 Feb 2020 09:33:57 -0800
> >
> > Code I used:
> >
> > (defun make-lines (n)
> >   (mapconcat #'number-to-string
> >              (number-sequence 0 n) "\n"))
> >
> > (let ((map (make-sparse-keymap)))
> >   (define-key map (kbd "C-f") (lambda ()
> >                                 (interactive)
> >                                 (let ((inhibit-field-text-motion t))
> >                                   (goto-char (point-min)))
> >                                 (message "%S"
> >                                          (read-key
> >                                           (concat
> >                                            (make-lines 10)
> >                                            "\nTest2")))
> >                                 (abort-recursive-edit)))
> >   (read-from-minibuffer (concat (make-lines 10) "\nTest1: ") nil map))
> >
> > With this code in the clipboard, I start emacs -Q (again, 27.0.60
> > commit 75a9eee8b), and immediately hit the following sequence of keys:
> >
> > C-y
> > M-x eval-buffer RET
> > C-f
> >
> > The eval-buffer results are initially as expected. However, after
> > hitting C-f, the minibuffer then becomes:
> >
> > 0
> > 1
> > 2
> > 3
> > 4
> > 5
> > 6
> > 7
> > 8
> > 9
> > 10
> > Test1:  [0
> > 1
> > 2
> > 3
> > 4
> >
> > with point at the very beginning of the minibuffer (first 0).
>
> Looks like the intended behavior for this code: the "[0 ..." part is
> the text of the message displayed by the command bound to C-f; it is
> enclosed in brackets to indicate that it is a message text separate
> from the rest of the prompt.  This display of echo-area messages that
> attempts not to overwrite the minibuffer prompt in an active
> minibuffer is a new feature of Emacs 27.  By default, Emacs will not
> let the mini-window grow enough to show the entire combined text of
> the prompt and the message, but if you set max-mini-window-height to a
> value 22 or greater, you will see this:
>
>   0
>   1
>   2
>   3
>   4
>   5
>   6
>   7
>   8
>   9
>   10
>   Test1:  [0
>   1
>   2
>   3
>   4
>   5
>   6
>   7
>   8
>   9
>   10
>   Test2]
>
> which is what I would expect, given the code you presented.
>
> Going back to the original report, what is the bug here?
>
> Thanks.

bug#39564:

[Matt Kramer]

Followup: The regression in Ivy appears to be fixed when
set-message-function is bound to nil at the top of the misbehaving
function. In general, it seems like, given the new defaults defined in
http://git.savannah.gnu.org/cgit/emacs.git/commit/?id=485b423e8f0df2711a850be7f254665f64ab0bdb,
it will be necessary to make a similar change to any existing function
that, say, calls read-key under the assumption that the prompt will
take over the mini-window. (At least when the prompt contains multiple
lines). I guess that's the fundamental issue here. The new behavior
may be a nice improvement, but it's unclear how much code there is out
there that relies on the old behavior.

(For the record, it looks like the Ivy discussion has moved to
https://github.com/abo-abo/swiper/issues/2397)

On Sun, Mar 1, 2020 at 2:26 PM Matt Kramer <mccleetus@gmail.com> wrote:
>
> Thanks Eli for the explanation. Sorry for the trouble. It looks like
> Ivy (at least, in ivy-dispatching-done) assumes the old behavior, to
> wit, that echo-area messages will overwrite the minibuffer prompt,
> leading to the regression discussed in
> https://github.com/abo-abo/swiper/issues/2444. The conversation will
> continue over there, I guess.
>
> On Sat, Feb 29, 2020 at 12:17 AM Eli Zaretskii <eliz@gnu.org> wrote:
> >
> > > From: Matt Kramer <mccleetus@gmail.com>
> > > Date: Fri, 28 Feb 2020 09:33:57 -0800
> > >
> > > Code I used:
> > >
> > > (defun make-lines (n)
> > >   (mapconcat #'number-to-string
> > >              (number-sequence 0 n) "\n"))
> > >
> > > (let ((map (make-sparse-keymap)))
> > >   (define-key map (kbd "C-f") (lambda ()
> > >                                 (interactive)
> > >                                 (let ((inhibit-field-text-motion t))
> > >                                   (goto-char (point-min)))
> > >                                 (message "%S"
> > >                                          (read-key
> > >                                           (concat
> > >                                            (make-lines 10)
> > >                                            "\nTest2")))
> > >                                 (abort-recursive-edit)))
> > >   (read-from-minibuffer (concat (make-lines 10) "\nTest1: ") nil map))
> > >
> > > With this code in the clipboard, I start emacs -Q (again, 27.0.60
> > > commit 75a9eee8b), and immediately hit the following sequence of keys:
> > >
> > > C-y
> > > M-x eval-buffer RET
> > > C-f
> > >
> > > The eval-buffer results are initially as expected. However, after
> > > hitting C-f, the minibuffer then becomes:
> > >
> > > 0
> > > 1
> > > 2
> > > 3
> > > 4
> > > 5
> > > 6
> > > 7
> > > 8
> > > 9
> > > 10
> > > Test1:  [0
> > > 1
> > > 2
> > > 3
> > > 4
> > >
> > > with point at the very beginning of the minibuffer (first 0).
> >
> > Looks like the intended behavior for this code: the "[0 ..." part is
> > the text of the message displayed by the command bound to C-f; it is
> > enclosed in brackets to indicate that it is a message text separate
> > from the rest of the prompt.  This display of echo-area messages that
> > attempts not to overwrite the minibuffer prompt in an active
> > minibuffer is a new feature of Emacs 27.  By default, Emacs will not
> > let the mini-window grow enough to show the entire combined text of
> > the prompt and the message, but if you set max-mini-window-height to a
> > value 22 or greater, you will see this:
> >
> >   0
> >   1
> >   2
> >   3
> >   4
> >   5
> >   6
> >   7
> >   8
> >   9
> >   10
> >   Test1:  [0
> >   1
> >   2
> >   3
> >   4
> >   5
> >   6
> >   7
> >   8
> >   9
> >   10
> >   Test2]
> >
> > which is what I would expect, given the code you presented.
> >
> > Going back to the original report, what is the bug here?
> >
> > Thanks.

bug#39564:

[Eli Zaretskii]

> From: Matt Kramer <mccleetus@gmail.com>
> Date: Sun, 1 Mar 2020 23:20:23 -0800
> Cc: 39564@debbugs.gnu.org
> 
> Followup: The regression in Ivy appears to be fixed when
> set-message-function is bound to nil at the top of the misbehaving
> function.

That is indeed the simplest solution, but it is not the best one.  It
would be better for Ivy to provide its own set-message-function which
plays by the new Emacs 27 rules, i.e. presents the message text in a
way that doesn't completely obscure the original prompt.

> In general, it seems like, given the new defaults defined in
> http://git.savannah.gnu.org/cgit/emacs.git/commit/?id=485b423e8f0df2711a850be7f254665f64ab0bdb,
> it will be necessary to make a similar change to any existing function
> that, say, calls read-key under the assumption that the prompt will
> take over the mini-window. (At least when the prompt contains multiple
> lines). I guess that's the fundamental issue here. The new behavior
> may be a nice improvement, but it's unclear how much code there is out
> there that relies on the old behavior.

Relying on the old behavior was always not a future-proof assumption,
so I see no way around the problem except fixing the code which makes
such assumptions, sorry.

bug#39564: 28.0.50; read-key function do not display the prompt if called from read-from-minibuffer

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> Relying on the old behavior was always not a future-proof assumption,
> so I see no way around the problem except fixing the code which makes
> such assumptions, sorry.

(I'm going through old bug reports that unfortunately weren't resolved
at the time.)

Reading this bug report, it seems the conclusion was that this was a
problem in Ivy, and not in Emacs?  So I'm therefore closing this bug
report.  If something should be done on the Emacs side, please respond
to the debbugs address and we'll reopen.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no