Error msg "Key sequence M - m SPC h SPC d SPC m starts with non-prefix key"

[sunlin7]

What happened?

There are error msg "Key sequence M - m SPC h SPC d SPC m starts with non-prefix key" for the describe-mode was binded to "M-m h d m" before loading helm.
Here are the lines to reproduce the issue, which will bind the describe-mode before loading the helm:

(global-set-key "M-m h d m" 'describe-mode)
(load-file "<PATH>/helm-core-20240510.1815/helm-core-autoloads.el")
(load-file "<PATH>/helm-20240510.1833/helm-autoloads.el")
(call-interactively 'helm)

The helm has special code to deal the describe-mode and leads the issue:

helm/helm-core.el

Lines 479 to 481 in 6d23a65

	;; Use `describe-mode' key in `global-map'.
	(dolist (k (where-is-internal #'describe-mode global-map))
	(define-key map k #'helm-help))

(defvar helm-map
;;...
    (define-key map (kbd "M-m")        #'helm-toggle-all-marks)
;;...
    ;; Use `describe-mode' key in `global-map'.
    (dolist (k (where-is-internal #'describe-mode global-map))
      (define-key map k #'helm-help))
;;...

This issue acctually happened on Spacemacs, was disscussed in syl20bnr/spacemacs#16397.

How to reproduce?

N/A

Helm Version

Master branch

Emacs Version

Emacs-29.1

OS

GNU/Linux

Relevant backtrace (if possible)

No response

Minimal configuration

• I agree using a minimal configuration

[thierryvolpiatto]

"lin.sun" ***@***.***> writes:

What happened? There are error msg "Key sequence M - m SPC h SPC d SPC m starts with non-prefix key" for the describe-mode was binded to "M-m h d m" before loading helm. Here are the lines to reproduce the issue, which will bind the describe-mode before loading the helm: (global-set-key "M-m h d m" 'describe-mode)

I don't understand in why this is related to Helm: 1) emacs -Q 2) Eval in scratch buffer: (global-set-key (kbd "M-m h d m") 'describe-mode) => Debugger entered--Lisp error: (error "Key sequence M-m h d m starts with non-prefix key ...") As expected...

…

-- Thierry

[sunlin7]

Hi @thierryvolpiatto
Currently helm will stop to work totally if user binding describe-mode to M-m h d m before loading helm.
The issue only affects one key-binding, helm shoulbe be able to continue works for other features.
So if helm gives a user-error friendly then continue, it should be better.

[thierryvolpiatto]

"lin.sun" ***@***.***> writes:

1. ( ) text/plain (*) text/html Hi @thierryvolpiatto Currently helm will stop to work totally if user binding describe-mode to M-m h d m before loading helm.

As (global-set-key (kbd "M-m h d m") 'describe-mode) or (global-set-key "M-m h d m" 'describe-mode) return an error I hardly see how you can bind such key, please enlight me.

The issue only affects one key-binding, helm can continue works for other features. So if helm gives a user-error friendly then continue, it would be better.

Same as above, if you have in your init file: (global-set-key (kbd "M-m h d m") 'describe-mode) and (require 'helm) (require 'helm) will never run, and all what is after also. So I wonder how one can bind such a key and continue loading helm afterward.

…

-- Thierry

[michael-heerdegen]

"lin.sun" ***@***.***> writes:

The issue only affects one key-binding, helm can continue works for other features. So if helm gives a user-error friendly then continue, it would be better.

I understand your viewpoint as a user. But such a rule would apply to _any_ key binding done anywhere in Emacs or by any other package. And this is not how Emacs is designed, or how key bindings are intended to work or be installed. AFAIU, your problem is not different from any other conflicting key bindings. So, if you explicitly define keys that are used by any package you want to use, this problem has to be resolved by you, in your configuration. When the conflicting binding's origin is something not under your control, e.g. another package, that would be a different story (you didn't tell us so far).

[sunlin7]

Hi @thierryvolpiatto @michael-heerdegen
Thanks for your explaination, and close this ticket for the original issue hacked by alias describe-mode to new name.
Refer: syl20bnr/spacemacs#16397