bug#42112: 27.0.91; whitespace-empty face not extended beyond EOL

bug#42112: 27.0.91; whitespace-empty face not extended beyond EOL

[Basil L. Contovounesios]

Severity: minor

Steps to reproduce:

0. emacs -Q
1. M-x whitespace-mode RET
2. M-<

In Emacs 26, line 3 is highlighted with the whitespace-empty face all
the way to the right fringe.

In Emacs 27, only the first two columns of line 3 are highlighted with
the whitespace-empty face.

Is this TRT?  Should whitespace-empty get an ':extend t' attribute or
inherit from some other face which already has that?

Thanks,

-- 
Basil

In GNU Emacs 27.0.91 (build 23, x86_64-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2020-06-28 built on thunk
Repository revision: cce00bef0313bc42beee8096d9312313889dc92d
Repository branch: emacs-27
Windowing system distributor 'The X.Org Foundation', version 11.0.12008000
System Description: Debian GNU/Linux bullseye/sid

Configured using:
 'configure 'CC=ccache gcc' 'CFLAGS=-O0 -g3 -ggdb -gdwarf-4'
 --config-cache --prefix=/home/blc/.local --program-suffix=27
 --enable-checking=yes,glyphs --enable-check-lisp-object-type
 --with-x-toolkit=lucid --with-file-notification=yes --with-x'

Configured features:
XAW3D XPM JPEG TIFF GIF PNG RSVG SOUND GPM DBUS GSETTINGS GLIB NOTIFY
INOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE HARFBUZZ M17N_FLT LIBOTF
XFT ZLIB TOOLKIT_SCROLL_BARS LUCID X11 XDBE XIM MODULES THREADS
LIBSYSTEMD JSON PDUMPER LCMS2 GMP

bug#42112: 27.0.91; whitespace-empty face not extended beyond EOL

[Eli Zaretskii]

> From: "Basil L. Contovounesios" <contovob@tcd.ie>
> Date: Sun, 28 Jun 2020 17:41:48 +0100
> 
> 0. emacs -Q
> 1. M-x whitespace-mode RET
> 2. M-<
> 
> In Emacs 26, line 3 is highlighted with the whitespace-empty face all
> the way to the right fringe.
> 
> In Emacs 27, only the first two columns of line 3 are highlighted with
> the whitespace-empty face.
> 
> Is this TRT?

I don't know: I don't use this mode.

> Should whitespace-empty get an ':extend t' attribute or inherit from
> some other face which already has that?

If we want the empty lines to be shown in this face in their entirety,
then it should have the :extend attribute, yes.  Just make sure it
looks OK with underline and other non-color attributes.

bug#42112: 27.0.91; whitespace-empty face not extended beyond EOL

[Basil L. Contovounesios]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: "Basil L. Contovounesios" <contovob@tcd.ie>
>> Date: Sun, 28 Jun 2020 17:41:48 +0100
>> 
>> 0. emacs -Q
>> 1. M-x whitespace-mode RET
>> 2. M-<
>> 
>> In Emacs 26, line 3 is highlighted with the whitespace-empty face all
>> the way to the right fringe.
>> 
>> In Emacs 27, only the first two columns of line 3 are highlighted with
>> the whitespace-empty face.
>> 
>> Is this TRT?
>
> I don't know: I don't use this mode.

I do, but I'm not sure what constitutes correct behaviour.  I guess the
Emacs 26 behaviour is how the feature was designed and what users have
come to expect, in which case Emacs 27 exhibits a regression.

>> Should whitespace-empty get an ':extend t' attribute or inherit from
>> some other face which already has that?
>
> If we want the empty lines to be shown in this face in their entirety,
> then it should have the :extend attribute, yes.

Is there any practical difference or preference between giving
whitespace-empty an :extend attribute vs making it inherit from a face
with an :extend attribute?

> Just make sure it looks OK with underline and other non-color
> attributes.

Will do in about a week's time if no-one beats me to it.

Thanks,

-- 
Basil

bug#42112: 27.0.91; whitespace-empty face not extended beyond EOL

[Eli Zaretskii]

> From: "Basil L. Contovounesios" <contovob@tcd.ie>
> Cc: 42112@debbugs.gnu.org
> Date: Sun, 28 Jun 2020 18:34:56 +0100
> 
> Is there any practical difference or preference between giving
> whitespace-empty an :extend attribute vs making it inherit from a face
> with an :extend attribute?

Inheritance makes display slightly slower (due to the need to chase
the inheritance chain).  And frankly I don't see why we would need to
use inheritance here in the first place.

bug#42112: 27.0.91; whitespace-empty face not extended beyond EOL

[Lars Ingebrigtsen]

"Basil L. Contovounesios" <contovob@tcd.ie> writes:

> In Emacs 26, line 3 is highlighted with the whitespace-empty face all
> the way to the right fringe.

I've now restored this in Emacs 28.

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