bug#47566: 28.0.50; diff-hl should use `repeat-mode' ... and not `smartrep'

[Juri Linkov]

>> Also, AFAICT the indication (whether in the mode-line or in the echo
>> area) only shows up once I start repeating a key (e.g. after C-x o o),
>> not when I first hit a repeatable key (e.g. after C-x o).
>
> Strange, I see it immediately after C-x o.

Could you please try to move 'force-mode-line-update' out of condition,
so it updates the mode-line on activating the repeat map as well:

#+begin_src emacs-lisp
(defun repeat-echo-mode-line (map)
  "Display the repeat indicator in the mode line."
  (if map
      (unless (assq 'repeat-in-progress mode-line-modes)
        (add-to-list 'mode-line-modes (list 'repeat-in-progress
                                            repeat-echo-mode-line-string))))
  (force-mode-line-update t))
#+end_src

Maybe your mode-line is not updated immediately?