bug#62573: 29.0.60; Cursor color not being inverted in emacs-29

[Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Daniel Martín <mardani29@yahoo.es>
>> Cc: Al Haji-Ali <abdo.haji.ali@gmail.com>,  62573@debbugs.gnu.org,
>>  luangruo@yahoo.com
>> Date: Sat, 01 Apr 2023 21:56:33 +0200
>> 
>> This bug is a regression caused by
>> 07715630ad9df9cb681cbadecbaf73fc9c698061.  (Adding Po Lu to the CC.)
>> 
>> >From what I see, the font display refactor removed this code from
>> src/nsterm.m:
>> 
>> -  face = FACE_FROM_ID_OR_NULL (f, phys_cursor_glyph->face_id);
>> -  if (face && NS_FACE_BACKGROUND (face)
>> -      == ns_index_color (FRAME_CURSOR_COLOR (f), f))
>> -    {
>> -      [ns_lookup_indexed_color (NS_FACE_FOREGROUND (face), f) set];
>> -      hollow_color = FRAME_CURSOR_COLOR (f);
>> -    }
>> -  else
>> 
>> which seems to be responsible for the cursor color change when the
>> background face color is the same as the cursor color.  I can't find
>> that logic in the current code, so I think we miss it from the
>> refactoring.
>> 
>> I've solved the bug by replicating that logic in the appropriate places,
>> nsterm.m and macfont.m:
>
> This regression should be fixed on the release branch, but the patch
> you propose is quite large.  Can't we simply reinstate the removed
> code, and apply the changes you propose only on master?

Unfortunately not, as that would involve removing the ability to
properly display mouse face with the Emacs 29 redisplay.