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#73552
obsolete (and broken) face attribute :reverse-video
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Your bug report
#73552: obsolete (and broken) face attribute :reverse-video
which was filed against the emacs package, has been closed.
The explanation is attached below, along with your original report.
If you require more details, please reply to 73552 <at> debbugs.gnu.org.
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73552: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=73552
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29 sep. 2024 kl. 15.49 skrev Eli Zaretskii <eliz <at> gnu.org>:
> I think the use of :reverse-video in make-mode.el should be changed to
> :inverse-video.
Oh, certainly (compiling that file now yields a warning).
The few extant uses of :reverse-video discovered so far seem to be fall-back cases for non-colour displays, decidedly a rarity these days.
> Otherwise, I'm okay with retiring this old and
> half-supported alias.
Thank you, now done.
29 sep. 2024 kl. 15.55 skrev Stefan Kangas <stefankangas <at> gmail.com>:
> We could start by doing s/:bold t/:weight bold/ and
> s/:italic t/:slant italic/ in our tree.
Yes, maybe later. At least these still work, and are widely used by external packages.
> I'd propose adding obsoletion warnings for :bold and :italic. I note
> that they are not documented in the elisp manual.
Wr probably should but the compilation warnings only catch constant arguments to `defface`. Other uses (themes, font-lock, computed text properties, non-constant arguments to defface, etc) aren't caught; that would require a run-time warning.
Anyway, we're done with :reverse-video, thanks everyone!
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The face attribute keyword :reverse-video has been broken in defface for a long time, and it's not used very much, so I added a compiler warning and a notice to NEWS.
This keyword along with :bold and :italic have been obsolete for longer than that and aren't even mentioned in any documentation (on purpose) but in the internal face-and-display machinery they still partly work.
I'm not quite sure why :reverse-video doesn't work in defface. Demo, in *scratch*:
(defface myface '((t :reverse-video t)) "my face")
(insert (propertize "bon bon" 'font-lock-face 'myface) ?\n)
=> bon bon ; not inverted
(insert (propertize "non non" 'font-lock-face '(:reverse-video t)) ?\n)
=> non non ; inverted
I first blamed a simple 14 years old mistake in `custom-fix-face-spec` but fixing that doesn't help, not sure why. But it means that we probably don't need to fix it, and indeed there are precious few packages using :reverse-video. One is make-mode.el; outside Emacs, I only found one (yaml-mode).
While :bold and :italic are obsolete as well, they are used a lot more (and actually seem to work) so I'm not warning about them now.
To summarise:
- Should we fix `custom-fix-face-spec`? Maybe, or just stop pretending that it handles :reverse-video.
- Should we bother to fix what other mechanism preventing :reverse-video from working? Probably no.
- Should we remove :reverse-video from the display machinery? Yes, but maybe not now?
- Should we remove :bold and :italic? Yes, but definitely not now.
This bug report was last modified 235 days ago.
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