bug#33421: 26.1; hl-line face used as default

bug#33421: 26.1; hl-line face used as default

[E. Choroba]

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Hi,

When I use emacs 24.3.1 and run

   /usr/bin/emacs -Q

Then M-< followed by M-x global-hl-line-mode and M-x describe-face, emacs asks 
me

Describe face (default `font-lock-comment-delimiter-face'):

But when I use 26.1 and run

   /usr/local/bin/emacs -Q

and run exactly the same commands, emacs asks me

Describe face (default ‘hl-line’):

I have to turn hl-line off to get the name of the point's face. This makes the 
default value of the function useless.

It seems that

   (get-char-property (point) 'face)

returns hl-line in 26.1, but returns the actual face in 24.3.1.

See also 
https://emacs.stackexchange.com/questions/45492/hl-line-face-used-as-default-in-26-1

Thanks,

Ch.

In GNU Emacs 26.1 (build 1, x86_64-pc-linux-gnu, Motif Version 2.3.4)
  of 2018-09-10 built on still
Windowing system distributor 'The X.Org Foundation', version 11.0.11803000
System Description:	openSUSE Leap 42.3

Recent messages:
Wrote /home/choroba/1.sh
Saving file /home/choroba/1.sh...
Wrote /home/choroba/1.sh
Saving file /home/choroba/graphics...
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GNU Emacs 26.1 (build 1, x86_64-pc-linux-gnu, Motif Version 2.3.4) of 
2018-09-10
Making completion list...
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Making completion list...

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bug#33421: 26.1; hl-line face used as default

[Eli Zaretskii]

tags 33421 notabug
thanks

> Date: Sun, 18 Nov 2018 22:37:57 +0100 (CET)
> From: "E. Choroba" <choroba@matfyz.cz>
> 
> When I use emacs 24.3.1 and run
> 
>    /usr/bin/emacs -Q
> 
> Then M-< followed by M-x global-hl-line-mode and M-x describe-face, emacs asks 
> me
> 
> Describe face (default `font-lock-comment-delimiter-face'):
> 
> But when I use 26.1 and run
> 
>    /usr/local/bin/emacs -Q
> 
> and run exactly the same commands, emacs asks me
> 
> Describe face (default ‘hl-line’):
> 
> I have to turn hl-line off to get the name of the point's face. This makes the 
> default value of the function useless.

I can reproduce this, but for me both Emacs 26 and Emacs 24 behave the
same.  So I don't know why your Emacs 24 behaves differently, perhaps
it's due to some local changes that are not in upstream sources.

In any case, "M-x describe-face" is not the right tool when there
could be several text properties at the same position, because
describe-face can only name one face, and it selects the one that
affects the text the most.  I suggest to use another command instead,
"M-x describe-text-properties".  It will pop up a window with
information about all the properties at point, and you can then drill
down using the buttons in that window.

This is not a bug.

Thanks.