Changing the name of the function key <mouse-1> leads to problems

Question

I want to change the name of the function key <mouse-1> like so:
(define-key input-decode-map (kbd "<mouse-1>") (kbd "<jd:m1>"))

And thus bind the new name to an arbitrary function like so:
(define-key global-map (kbd "<jd:m1>") 'mouse-set-point)

But when testing the changes I get this error:

Debugger entered--Lisp error: (error "mouse-set-point must be bound to an event with parameters")
  call-interactively(mouse-set-point nil nil)
  command-execute(mouse-set-point)

Why does this functionality work for all other key functions but not the mouse key functions?

For example this works just fine:

(define-key input-decode-map (kbd "<tab>") (kbd "<jd:tab>"))
(define-key global-map (kbd "<jd:tab>") 'indent-for-tab-command)

Answer 1

The issue is the following:

(define-key input-decode-map [mouse-1] [jd:m1])

will convert any incoming "event with name mouse-1" into the event jd:m1, whereas you want to convert it to a similar "event with name jd:m1". More specifically, mouse events are not just symbols but have the form:

(NAME . METADATA)

where NAME may be equal to things like mouse-1 and METADATA holds info such as the location where the user pressed this mouse button.

IOW, your remapping turns (mouse-1 . METADATA) into a "dumb" jd:m1 losing the METADATA along the way.

Doing the kind of remapping you propose is actually tricky for all kinds of arbitrary reasons. I suggest you look at the source code of mouse--click-1-maybe-follows-link to see what it might involve.

Basically, you'll need something like:

(define-key input-decode-map [mouse-1]
  (lambda (&optional _prompt)
    (let ((newname 'jd:m1))
      ;; Copy the `event-kind` at the first occasion.
      (unless (get newname 'event-kind)
        (put newname 'event-kind
             (get (car last-input-event) 'event-kind)))
      ;; Modify the event in-place, otherwise we can get a prefix
      ;; added again, so a click on the header-line turns
      ;; into a [header-line header-line <newname>] :-(.
      ;; See fake_prefixed_keys in src/keyboard.c's.
      (setf (car last-input-event) newname)
      (vector last-input-event))))

Yuck!