Eli Zaretskii <eliz@gnu.org> writes:

>> From: Alex <agrambot@gmail.com>
>> Cc: emacs-devel@gnu.org
>> Date: Sun, 16 Jul 2017 01:30:16 -0600
>> 
>> It looks like I could just leave the defgroup definition in
>> display-line-numbers.el and the variables in cus-start.el can still use
>> it without display-line-numbers.el being preloaded.
>> 
>> Which file would you rather have it in?
>
> All else being equal, I think having as much as possible in
> display-line-numbers.el would be better, as it avoids scattering
> related stuff across different files.

I agree. Here's an updated patch that includes this as well as other
improvements: