bug#42839: [PATCH] Support displaying line numbers in goto-line

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Wed, 12 Aug 2020 23:30:42 -0700
> 
> +       (let ((showing display-line-numbers))
> +         (unwind-protect
> +             (progn
> +               (when (not showing)
> +                 (display-line-numbers-mode 1))
> +               (list (read-number (format "Goto line%s: " buffer-prompt)
> +                                  (list default (line-number-at-pos))
> +                                  'goto-line-history)
> +                  buffer))
> +           (when (not showing)
> +             (display-line-numbers-mode -1)))))))

The variable display-line-numbers is not a simple boolean, it can have
several values.  I think you intended to show absolute line numbers in
this case, so just testing whether display-line-numbers is non-nil is
not enough.  Similarly, restoring the original setting needs more than
just a call to display-line-numbers-mode.

And this needs a NEWS entry.

Other than that, if someone wants this optional feature, why not?