Re: Weird capitalisation in "<mode-name> enabled in current buffer"

[Stephen Berman]

On Wed, 31 Aug 2022 13:34:12 +0200 Joost Kremers <joostkremers@fastmail.fm> 
wrote:

> Hi list,
>
> I "wrote" a teeny-tiny minor mode `dedicated-mode` inspired by the same-name
> mode available on Melpa. It's basically just a single line:
>
> ```
> (define-minor-mode dedicated-mode
>   "Minor mode to dedicate a window to its buffer."
>   :init-value nil :lighter " D" :global nil
>   (set-window-dedicated-p nil dedicated-mode))
> ```
>
> Now, never mind that this shouldn't be a minor mode at all, since it should be
> linked to the window, not the buffer. What's strange is that when I activate
> this mode, the message in the echo area reads:
>
> DeDicateD moDe enabled in current buffer
>
> Note the capital Ds in the words "DeDicateD moDe". Same thing happens when I
> deactivate the mode.
>
> Funny thing is, if I change the :lighter in the mode definition to lower case
> "d", the capitalisation does not happen.
>
> So, what should I file this under? Bug or joke? :D

It's due to the last line in easy-mmode-pretty-mode-name:

      ;; Replace any (case-insensitive) matches for LIGHTER in NAME
      ;; with a literal LIGHTER.  E.g., if NAME is "Iimage mode" and
      ;; LIGHTER is " iImag", then this will produce "iImage mode".
      ;; (LIGHTER normally comes from the mode-line string passed to
      ;; define-minor-mode, and normally includes at least one leading
      ;; space.)
      (replace-regexp-in-string (regexp-quote lighter) lighter name t t))))

The patch below fixes your use case but breaks the case mentioned in the
above comment.  A fix handling both cases might be tricky.

Steve Berman

diff --git a/lisp/emacs-lisp/easy-mmode.el b/lisp/emacs-lisp/easy-mmode.el
index c3a4e9fc7a..e70946921e 100644
--- a/lisp/emacs-lisp/easy-mmode.el
+++ b/lisp/emacs-lisp/easy-mmode.el
@@ -79,7 +79,8 @@ easy-mmode-pretty-mode-name
       ;; (LIGHTER normally comes from the mode-line string passed to
       ;; define-minor-mode, and normally includes at least one leading
       ;; space.)
-      (replace-regexp-in-string (regexp-quote lighter) lighter name t t))))
+      ;; (replace-regexp-in-string (regexp-quote lighter) lighter name t t)
+      name)))

 (defconst easy-mmode--arg-docstring
   "This is a %sminor mode.  If called interactively, toggle the