bug#45915: 28.0.90; deletechar distorts org-table

[Ihor Radchenko <yantar92@gmail.com>]

Tak Kunihiro <homeros.misasa@gmail.com> writes:

> Thank you for the patch.  I applied the patch to org-table.el on Emacs
> 28.0.90.
>
> And I still see the problem there.  Is the problem solved by the patch
> on your environment?

The problem was solved on my side, but _not_ using your reproducer
explicitly. If I save the buffer from your reproducer as a file and
later open in, the patch does solve the problem. However, when I run the
reproducer as is, a similar-looking problem emerges.

Using your reproducer, something very strange is going on.
With the patch, <delete> is correctly mapped to org-delete-char, which
calls (delete-char 1) at some point. However, this (delete-char 1)
somehow deletes 2!! chars instead of 1. This should be some tricky Emacs
issue (bug?). In any case, I am not ready to dig into what is going on
in Emacs. I do not think that such problem is going to appear during
normal Emacs usage. At least, I was unable to reproduce it by other
means than your reproducer function.

To illustrate the issue, one can use the following version of the
reproducer. Feel free to report this to Emacs upstream.

(defun emacs-bug-reproduce-45915 ()
  "Reproduce bug#45915."
  ;; (gnus-read-ephemeral-emacs-bug-group 45915)
  (interactive)
  (with-current-buffer (get-buffer-create "*temp buffer*")
    (erase-buffer)
    (require 'org)
    (orgtbl-mode 1)
    (insert (format "emacs-version: %s, org-version: %s\n" emacs-version org-version))
    (insert "|   | rownames |
| / | <l>      |
|---+----------|
|   | a        |"))
  (switch-to-buffer-other-window "*temp buffer*")
  (execute-kbd-macro (kbd "M-< C-n C-n C-n C-n C-f C-f"))
  (message "I will hit S-<return>.")
  (sit-for 2)
  (execute-kbd-macro (kbd "S-<return>"))
  (message "I will hit <delete>.")
  (sit-for 2)
  ;;  (execute-kbd-macro (kbd "<delete>"))
  (delete-char 1)
  (message "I will call previous-line.")
  (sit-for 2)
  (call-interactively 'previous-line))

Best,
Ihor