org-element-cache warning when saving with ws-butler-keep-whitespace-before-point

[bitclick]

affected version:

GNU Emacs     v27.2           
Doom core     v3.0.0-dev      
Doom modules  v22.08.0-dev     grafted, HEAD -> master, origin/master, origin/HEAD c44bc81 2022-08-19 11:24:34 +0200
Org mode version 9.6 (9.6-??-00adad9)

problem

• ws-butler-keep-whitespace-before-point set to t
• org-element-use-cache is set to t
• saving an orgmode buffer, with trailing spaces before the point
• warning pops up:

Warning (org-element-cache): org-element--cache: Unregistered buffer modifications detected. Resetting.
If this warning appears regularly, please report the warning text to Org mode mailing list (M-x org-submit-bug-report).
The buffer is: xyz.org
 Current command: nil
 Backtrace:
"  backtrace-to-string(nil)
  org-element--cache-sync(#<buffer xyz.org>)
  apply(org-element--cache-sync #<buffer xyz.org>)
  timer-event-handler([t 0 5 323697 nil org-element--cache-sync (#<buffer xyz.org>) idle 850999])
"

notes

• i think it is because ws-butler-after-save modifies the buffer while inhibiting org-element change-hook functions to run (org-element--cache-before-change and/or org-element--cache-after-change)
• see fix in org-transclusion for a solution to a similar problem
• workaround is disabling org-element cache 😒

[bitclick]

dooms modules add an advice to ws-butler-after-save (modules/ui/modeline/config.el):

  ;; Some functions modify the buffer, causing the modeline to show a false
  ;; modified state, so force them to behave.
  (defadvice! +modeline--inhibit-modification-hooks-a (fn &rest args)
    :around #'ws-butler-after-save
    (with-silent-modifications (apply fn args)))

but this seems not to be the cause (i tested it without the advice), problem still occurs

[postcert]

I know it's a bit late but I created a ws-butler-trim-predicate function that helps me partially avoid this issue.

(after! ws-butler
  (setq ws-butler-trim-predicate
      (lambda (beg end)
        (let* ((current-line (line-number-at-pos))
               (beg-line (line-number-at-pos beg))
               (end-line (line-number-at-pos end))
               ;; Assuming the use of evil-mode for insert mode detection. Adjust if using a different system.
               (in-insert-mode (and (bound-and-true-p evil-mode)
                                    (eq 'insert evil-state))))
          ;; Return true (allow trimming) unless in insert mode and the current line is within the region.
          (not (and in-insert-mode
                    (>= current-line beg-line)
                    (<= current-line end-line))))))
)

Simply avoid trimming a region if it contains the $current_line I am in insert-mode with.
I currently use auto-save @ the default interval so it'll eventually clean up any trailing whitespace.

For my use this expectation only fails when I switch buffers quickly (auto-save won't trigger anymore) but that is unrelated to ws-butler. I hope it helps @bitclick