Hi Eli, thanks for your feedback on this!

Why not add this as an optional feature to abbrev.el, conditional on
some defcustom?

I should have mentioned that that is what I had in mind, actually,

if this would ever be included in Emacs.

> (message "Abbrev suggestion: The word `%s' has the abbrev
> `%s' defined" (car abbrev) (cdr abbrev)))))

I'd suggest to make the message text shorter, to make the probability
of its becoming longer than the echo-area width, which would resize
the mini-window and cause an annoying redisplay. I'd just drop the
part before the colon, as the rest already says there is an abbrev.

I changed that to:

(message "You can write `%s' using the abbrev `%s'."

(car abbrev) (cdr abbrev)))))

I tried to make it similar to how we "hint" users about keybindings to

commands.