u and C-r doesn't work in new buffer with undo-tree as evil-undo-system

[tttuuu888]

Issue type

• Bug report

Environment

Emacs version: GNU Emacs 27.1
Operating System: Arch linux
Evil version: Evil version 1.14.0
Evil installation type: MELPA
Graphical/Terminal: Both
Tested in a make emacs session (see CONTRIBUTING.md): No

Reproduction steps

• Start Emacs

$ emacs -Q

;;; *scratch* buffer
(package-initialize)
(custom-set-variables '(evil-undo-system 'undo-tree))
(evil-mode)
(global-undo-tree-mode)

2-1.
u and C-r works fine in scratch buffer
2-2.
Open any file
u and C-r works fine.
2-3.
Open new buffer by C-x b test-buffer
u and C-r doesn't work with message "user-error: Enable ‘global-undo-tree-mode’ to use undo-tree commands."

Expected behavior

u and C-r should work in new buffer too.

Actual behavior

u and C-r doesn't work with message "user-error: Enable ‘global-undo-tree-mode’ to use undo-tree commands."

Further notes

This seems happening only when using undo-tree as evil-undo-system. (undo-tree version : 0.7.5)
This wasn't reproduced when tested in make emacs session.
This is happening only in new buffer.

Since this isn't reproduced in make emacs session, I looked into this quite for a while but couldn't figure it out.
I apologize in advance if it's a configuration issue, not a bug.

Thanks.

[tttuuu888]

Additionally, this happens simply because undo-tree-mode becomes nil with above reproduction steps.
And undo-tree-mode didn't become nil in same condition without turning evil-mode on.

[wasamasa]

The PR that introduced this change removed this integration code:

(when (and (require 'undo-tree nil t)
           (fboundp 'global-undo-tree-mode))
  (global-undo-tree-mode 1))

(eval-after-load 'undo-tree
  '(with-no-warnings
     (defun evil-turn-on-undo-tree-mode ()
       "Enable `undo-tree-mode' if evil is enabled.
This function enables `undo-tree-mode' when Evil is activated in
some buffer, but only if `global-undo-tree-mode' is also
activated."
       (when (and (boundp 'global-undo-tree-mode)
                  global-undo-tree-mode)
         (turn-on-undo-tree-mode)))

     (add-hook 'evil-local-mode-hook #'evil-turn-on-undo-tree-mode)))

Could you please test whether adding that code to your repro resolves the issue? Alternatively this simplified version:

(global-undo-tree-mode)
(add-hook 'evil-local-mode-hook 'turn-on-undo-tree-mode)

[tttuuu888]

@wasamasa Thank you for your opinion.

I tested both code and both fixed the issue. Actually I've been temporarily using the second code for this issue in my configuration. I thought it's temporal solution because now evil-mode use 'evil-undo-system' and this direct setting could be object to new 'evil-undo-system'.

Anyway both version fix my issue. I hope this result could be helpful. Thank you again.