Re: Emacs pretest: highlight line number in display-line-numbers-mode?

[Robert Pluim <rpluim@gmail.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> Date: Thu, 19 Oct 2017 13:43:06 -0700 (PDT)
>> From: Drew Adams <drew.adams@oracle.com>
>> 
>> > This face is by default the same as line-number because of 2 reasons:
>> > 
>> >   . linum-mode did the same
>> 
>> ...chasing that rabbit: Why did `linum-mode' do that?
>
> I don't know, but too many differences from a previous feature tend to
> annoy people IME.

nlinum-mode has an option to highlight the current line, disabled by
default (I never turned it on because I didn't know it existed, but I
do have it turned on for the builtin support)

I'd vote for having the current line face have a background colour
set. Calculating line numbers is going to slow things down anyway, so
a little less speed doesn't matter to me. Something like:

diff --git i/lisp/faces.el w/lisp/faces.el
index a5f1d1dd32..a2bb2cd1b3 100644
--- i/lisp/faces.el
+++ w/lisp/faces.el
@@ -2487,7 +2487,12 @@ line-number
   :group 'display-line-numbers)
 
 (defface line-number-current-line
-  '((t :inherit line-number))
+  '((((class color) (background light))
+     :inherit line-number :background "grey95")
+    (((class color) (background dark))
+     :inherit line-number :background "grey10")
+    (t
+     :inherit line-number :background "gray"))
   "Face for displaying the current line number.
 This face is used when `display-line-numbers' is non-nil.
 
Robert