Re: bug#48199: 28.0.50; Org mode surprisingly usurps Calendar key binding

[Stephen Berman]

[I added emacs-orgmode@gnu.org in the Cc:]

On Mon, 03 May 2021 18:07:25 +0200 Stephen Berman <stephen.berman@gmx.net> 
wrote:

> By default `i' is a prefix key in calendar-mode for commands that insert
> diary entries.  But if you happen to display a buffer that activates
> org-mode machinery, then `i' in calendar-mode becomes bound to
> org-agenda-diary-entry and typing it can raise a wrong-type-argument
> error.  This can happen by visiting a file in Org mode.  To reproduce:
>
> 0. emacs -Q
> 1. (sanity check:) Type `M-x calendar RET' and then in the Calendar
>    buffer type `i C-h': the *Help* buffer displays all the commands
>    invoked by `i' plus one or more keys.
> 2. Visit the file `ORG-NEWS' (e.g. by typing `C-h n C-x C-f O TAB RET').
> 3. Type `M-x calendar RET' and then in the Calendar buffer type `i'
> => Wrong type argument: commandp, org-agenda-diary-entry
>
> This can also catch users by surprise, e.g. in Gnus.  To reproduce,
> replace step 2 above by the following:
>
> 2a. Type `M-x gnus', answer `y' at the prompt; in the Gnus buffer type
>     `B RET news.gmane.io RET'.
> 2b. In the *Gnus Browse Server* buffer type `C-s humani' to put point on
>     the gmane.emacs.humanities group; type RET to enter it.
> 2c. Type `j <87sg6wulu6.fsf@localhost> RET', which displays an article
>     containing an org-mode source code block.
> 3. As above, resulting in the same error (when done from emacs -Q).
>
> The Org mode manual (info "(org) Agenda Commands") does describe its use
> of the `i' binding in the Calendar, and if Org mode has its own versions
> of the commands that use `i' by default in calendar-mode, then
> overriding the calendar-mode bindings is no problem for Org Agenda
> users, but those bindings should not be overridden just by displaying a
> buffer that happens to be in org-mode or happens to contain an Org
> source code block.

The following patch fixes the problem for me:

diff --git a/lisp/org/org-compat.el b/lisp/org/org-compat.el
index 1f4e2e8308..b68e5b58fc 100644
--- a/lisp/org/org-compat.el
+++ b/lisp/org/org-compat.el
@@ -1151,8 +1151,8 @@ org--setup-calendar-bindings
     ((guard (not (lookup-key calendar-mode-map "c")))
      (local-set-key "c" #'org-calendar-goto-agenda))
     (_ nil))
-  (unless (and (boundp 'org-agenda-diary-file)
-              (eq org-agenda-diary-file 'diary-file))
+  (when (and (boundp 'org-agenda-diary-file)
+            (not (eq org-agenda-diary-file 'diary-file)))
     (local-set-key org-calendar-insert-diary-entry-key
                   #'org-agenda-diary-entry)))

I have to admit, though, that I don't understand why the version with
`unless' results in the bug, since in the recipes I gave
org-agenda-diary-file is unbound and, indeed, when I instrument the
unpatched org--setup-calendar-bindings and step through it on calling
`calendar', the org-calendar-insert-diary-entry-key local-set-key call
is skipped as expected.  But "c" does get locally set, so if I type `c'
in the Calendar buffer, it displays the Org Agenda, and if I then type
`i' in the Calendar buffer, I now get prompted with a choice menu for
the type of diary entry, but whichever I choose, the result is the
user-error "Don't know which date to use for diary entry", evidently
because there is indeed no org-agenda-diary-file with the necessary text
properties.  So somehow the "i" binding is made even though the code
should prevent this (and does under Edebug but not when executed
normally).

With the above patch, after typing `c' in the Calendar buffer, `i' is
still unbound, as it should be, but if I changed the value of
org-agenda-diary-file from the default 'diary-file to some file, then
`i' works with Org Agenda as documented.

Steve Berman