Change of behavior of "space" display property and face property

Change of behavior of "space" display property and face property

[Qiantan Hong]

Open an empty text file, M-: (insert #(" " 0 1 (face (:underline t) display (space :align-to right))))

On Emacs 28, this produce a blank line with underline.

On Emacs 29, this produce a blank line without underline. In general, “space” display 
seem to disregard any face property.

Is this intended or is this a bug? “space” display respecting face property is useful for
typesetting. For example. I use it to display a horizontal separator under my header line.

Best,
Qiantan

Re: Change of behavior of "space" display property and face property

[Po Lu]

Qiantan Hong <qthong@stanford.edu> writes:

> Open an empty text file, M-: (insert #(" " 0 1 (face (:underline t) display (space :align-to right))))
>
> On Emacs 28, this produce a blank line with underline.
>
> On Emacs 29, this produce a blank line without underline. In general, “space” display 
> seem to disregard any face property.
>
> Is this intended or is this a bug? “space” display respecting face property is useful for
> typesetting. For example. I use it to display a horizontal separator under my header line.
>
> Best,
> Qiantan

That is almost certainly a bug, but I cannot be certain without knowing
what toolkit and window system you built Emacs with.

I remember fixing something similar on the NS build months back.

Re: Change of behavior of "space" display property and face property

[Eli Zaretskii]

> From: Po Lu <luangruo@yahoo.com>
> Cc: "emacs-devel@gnu.org" <emacs-devel@gnu.org>
> Date: Tue, 04 Oct 2022 14:34:28 +0800
> 
> Qiantan Hong <qthong@stanford.edu> writes:
> 
> > Open an empty text file, M-: (insert #(" " 0 1 (face (:underline t) display (space :align-to right))))
> >
> > On Emacs 28, this produce a blank line with underline.
> >
> > On Emacs 29, this produce a blank line without underline. In general, “space” display 
> > seem to disregard any face property.
> >
> > Is this intended or is this a bug? “space” display respecting face property is useful for
> > typesetting. For example. I use it to display a horizontal separator under my header line.
> >
> > Best,
> > Qiantan
> 
> That is almost certainly a bug, but I cannot be certain without knowing
> what toolkit and window system you built Emacs with.

I cannot reproduce this here, on MS-Windows.  The recipe produces the
same display for me in both Emacs 28 and Emacs 29.  So if this is
reproducible on some system, it is most probably a bug in the
terminal-specific display backend.

Re: Change of behavior of "space" display property and face property

[Po Lu]

Eli Zaretskii <eliz@gnu.org> writes:

> I cannot reproduce this here, on MS-Windows.  The recipe produces the
> same display for me in both Emacs 28 and Emacs 29.  So if this is
> reproducible on some system, it is most probably a bug in the
> terminal-specific display backend.

That's also what I thought, since the problem doesn't happen on X.

Re: Change of behavior of "space" display property and face property

[Visuwesh]

[செவ்வாய் அக்டோபர் 04, 2022] Eli Zaretskii wrote:

>> From: Po Lu <luangruo@yahoo.com>
>> Cc: "emacs-devel@gnu.org" <emacs-devel@gnu.org>
>> Date: Tue, 04 Oct 2022 14:34:28 +0800
>> 
>> Qiantan Hong <qthong@stanford.edu> writes:
>> 
>> > Open an empty text file, M-: (insert #(" " 0 1 (face (:underline t) display (space :align-to right))))
>> >
>> > On Emacs 28, this produce a blank line with underline.
>> >
>> > On Emacs 29, this produce a blank line without underline. In general, “space” display 
>> > seem to disregard any face property.
>> >
>> > Is this intended or is this a bug? “space” display respecting face property is useful for
>> > typesetting. For example. I use it to display a horizontal separator under my header line.
>> >
>> > Best,
>> > Qiantan
>> 
>> That is almost certainly a bug, but I cannot be certain without knowing
>> what toolkit and window system you built Emacs with.
>
> I cannot reproduce this here, on MS-Windows.  The recipe produces the
> same display for me in both Emacs 28 and Emacs 29.  So if this is
> reproducible on some system, it is most probably a bug in the
> terminal-specific display backend.

Cannot reproduce on Emacs 29 using the Lucid backend, cairo and HarfBuzz either.

Re: Change of behavior of "space" display property and face property

[Qiantan Hong]

I’m on NS. I just git pull’ed and the problem persist.

Emacs version:

GNU Emacs 29.0.50 (build 1, x86_64-apple-darwin21.5.0, NS appkit-2113.50 Version 12.4 (Build 21F79))
 of 2022-10-04

System version: macOS 12.4 (21F79)

Best,
Qiantan



> On Oct 3, 2022, at 11:34 PM, Po Lu <luangruo@yahoo.com> wrote:
> 
> Qiantan Hong <qthong@stanford.edu> writes:
> 
>> Open an empty text file, M-: (insert #(" " 0 1 (face (:underline t) display (space :align-to right))))
>> 
>> On Emacs 28, this produce a blank line with underline.
>> 
>> On Emacs 29, this produce a blank line without underline. In general, “space” display 
>> seem to disregard any face property.
>> 
>> Is this intended or is this a bug? “space” display respecting face property is useful for
>> typesetting. For example. I use it to display a horizontal separator under my header line.
>> 
>> Best,
>> Qiantan
> 
> That is almost certainly a bug, but I cannot be certain without knowing
> what toolkit and window system you built Emacs with.
> 
> I remember fixing something similar on the NS build months back.

Re: Change of behavior of "space" display property and face property

[Po Lu]

Qiantan Hong <qthong@stanford.edu> writes:

> I’m on NS. I just git pull’ed and the problem persist.
>
> Emacs version:
>
> GNU Emacs 29.0.50 (build 1, x86_64-apple-darwin21.5.0, NS appkit-2113.50 Version 12.4 (Build 21F79))
>  of 2022-10-04
>
> System version: macOS 12.4 (21F79)
>
> Best,
> Qiantan

Thanks, I will push a fix shortly (but it hasn't been tested on Mac OS,
just GNUstep.)