GNU bug report logs - #3862
23.1.50; error calling `documentation' on calendar-mode

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Message #5 received at submit <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Kevin Ryde <user42 <at> zip.com.au>
To: emacs-pretest-bug <at> gnu.org
Subject: 23.1.50; error calling `documentation' on calendar-mode
Date: Thu, 16 Jul 2009 09:50:38 +1000

In a recent cvs starting "emacs -Q" and evaluating

    (progn
      (require 'calendar)
      (documentation 'calendar-mode))

gets the error and backtrace below.

For what it's worth it works fine from the actual calendar buffer, but I
was trying in some program code where that wasn't the case.  I hoped I
could generally get the docs for any function from anywhere.

Also incidentally I tried a condition-case around it like

    (condition-case nil
        (documentation 'calendar-mode)
      (error nil))

and was surprised it still went to the debugger.  But maybe that's a
separate problem.



Debugger entered--Lisp error: (void-variable displayed-month)
  calendar-cursor-to-date(t 24)
  cal-menu-set-date-title(("--" ["Holidays" calendar-cursor-holidays] ["Mark date" calendar-set-mark] ["Sunrise/sunset" calendar-sunrise-sunset] ["Other calendars" calendar-print-other-dates] ("Prepare LaTeX buffer" ["Daily (1 page)" cal-tex-cursor-day] ["Weekly (1 page)" cal-tex-cursor-week] ["Weekly (2 pages)" cal-tex-cursor-week2] ["Weekly (other style; 1 page)" cal-tex-cursor-week-iso] ["Weekly (yet another style; 1 page)" cal-tex-cursor-week-monday] ["Monthly" cal-tex-cursor-month] ["Monthly (landscape)" cal-tex-cursor-month-landscape] ["Yearly" cal-tex-cursor-year] ["Yearly (landscape)" cal-tex-cursor-year-landscape] ("Filofax styles" ["Filofax Daily (one-day-per-page)" cal-tex-cursor-filofax-daily] ["Filofax Weekly (2-weeks-at-a-glance)" cal-tex-cursor-filofax-2week] ["Filofax Weekly (week-at-a-glance)" cal-tex-cursor-filofax-week] ["Filofax Yearly" cal-tex-cursor-filofax-year])) ("Write HTML calendar" ["For selected month" cal-html-cursor-month] ["For selected year" cal-html-cursor-year]) ["Diary entries" calendar-mouse-view-diary-entries :keys "d"] ["Insert diary entry" diary-insert-entry] ["Other diary file entries" calendar-mouse-view-other-diary-entries :keys "D"]))
  (easy-menu-filter-return (cal-menu-set-date-title menu) "cal-menu-mouse2")
  (lambda (menu) (easy-menu-filter-return (cal-menu-set-date-title menu) "cal-menu-mouse2"))(("--" ["Holidays" calendar-cursor-holidays] ["Mark date" calendar-set-mark] ["Sunrise/sunset" calendar-sunrise-sunset] ["Other calendars" calendar-print-other-dates] ("Prepare LaTeX buffer" ["Daily (1 page)" cal-tex-cursor-day] ["Weekly (1 page)" cal-tex-cursor-week] ["Weekly (2 pages)" cal-tex-cursor-week2] ["Weekly (other style; 1 page)" cal-tex-cursor-week-iso] ["Weekly (yet another style; 1 page)" cal-tex-cursor-week-monday] ["Monthly" cal-tex-cursor-month] ["Monthly (landscape)" cal-tex-cursor-month-landscape] ["Yearly" cal-tex-cursor-year] ["Yearly (landscape)" cal-tex-cursor-year-landscape] ("Filofax styles" ["Filofax Daily (one-day-per-page)" cal-tex-cursor-filofax-daily] ["Filofax Weekly (2-weeks-at-a-glance)" cal-tex-cursor-filofax-2week] ["Filofax Weekly (week-at-a-glance)" cal-tex-cursor-filofax-week] ["Filofax Yearly" cal-tex-cursor-filofax-year])) ("Write HTML calendar" ["For selected month" cal-html-cursor-month] ["For selected year" cal-html-cursor-year]) ["Diary entries" calendar-mouse-view-diary-entries :keys "d"] ["Insert diary entry" diary-insert-entry] ["Other diary file entries" calendar-mouse-view-other-diary-entries :keys "D"]))
  documentation(calendar-mode)
  (progn (require (quote calendar)) (documentation (quote calendar-mode)))
  eval-region(1 63 t (lambda (ignore) (goto-char 63) (quote (progn ... ...))))  ; Reading at buffer position 8
  apply(eval-region (1 63 t (lambda (ignore) (goto-char 63) (quote ...))))
  eval-defun-2()
  eval-defun(nil)
  call-interactively(eval-defun nil nil)




In GNU Emacs 23.1.50.1 (i586-pc-linux-gnu, GTK+ Version 2.16.4)
 of 2009-07-12 on blah.blah
configured using `configure  'CFLAGS=-O -g' '--prefix=/down/emacs/b/inst' '--with-x-toolkit=gtk''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_AU
  value of $XMODIFIERS: nil
  locale-coding-system: iso-latin-1-unix
  default-enable-multibyte-characters: t

Message #10 received at 3862 <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Kevin Ryde <user42 <at> zip.com.au>
Cc: 3862 <at> debbugs.gnu.org
Subject: Re: bug#3862: 23.1.50; error calling `documentation' on calendar-mode
Date: Wed, 15 Jul 2009 21:40:18 -0400

>     (progn
>       (require 'calendar)
>       (documentation 'calendar-mode))

> gets the error and backtrace below.

The docstring gets passed through substitute-command-keys which can run
arbitrary code via menu-item :filters (as well as via autoloaded
keymaps, actually).

> For what it's worth it works fine from the actual calendar buffer, but I
> was trying in some program code where that wasn't the case.  I hoped I
> could generally get the docs for any function from anywhere.

In the present case, there's a subtle bug in the :filter of the
calendar-mode-map (more specially in the menu-bar part of the map).

> Also incidentally I tried a condition-case around it like

>     (condition-case nil
>         (documentation 'calendar-mode)
>       (error nil))

> and was surprised it still went to the debugger.  But maybe that's a
> separate problem.

Indeed it's a separate problem: when the filter is run, it is presumed
it is "at top level" and so the error gets turned into a backtrace
without paying attention to surrounding condition-cases.  It's clearly
a bug, but it might be delicate to fix without introducing risks of
nasty crashes.


        Stefan

Message #13 received at 3862 <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: 3862 <at> debbugs.gnu.org, Kevin Ryde <user42 <at> zip.com.au>
Subject: Re: bug#3862: 23.1.50; error calling `documentation' on calendar-mode
Date: Thu, 16 Jul 2009 21:02:39 -0400

Stefan Monnier wrote:

> In the present case, there's a subtle bug in the :filter of the
> calendar-mode-map (more specially in the menu-bar part of the map).

Could you explain what the bug is? The error is coming from
cal-menu-set-date-title in a mouse-binding, which calls
calendar-cursor-to-date.

This has always assumed it is called from a calendar buffer, which
seems reasonable, and gives an error if it is not.

Also, why does C-h f calendar-mode work fine?


On a related note, I notice that the Emacs 22 behaviour, where it
displays an explicit error message "Not on a date" if called in the
calendar with point not a date, has been lost - now it is just silent.
I would like to get this back, but I can't figure out the Easymenu-Way
to do it.


Anyway, the following hack will suppress the original issue.


*** calendar.el	8 Jul 2009 02:48:13 -0000	1.283
--- calendar.el	17 Jul 2009 00:53:33 -0000
***************
*** 1811,1816 ****
--- 1811,1817 ----
    (with-current-buffer
        (if event (window-buffer (posn-window (event-start event)))
          (current-buffer))
+     (or (boundp 'displayed-month) (error "Not on a date!"))
      (save-excursion
        (and event (setq event (event-start event))
             (goto-char (posn-point event)))

Message #16 received at 3862 <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: 3862 <at> debbugs.gnu.org
Cc: Stefan Monnier <monnier <at> iro.umontreal.ca>, Kevin Ryde <user42 <at> zip.com.au>
Subject: Re: bug#3862: 23.1.50; error calling `documentation' on calendar-mode
Date: Fri, 17 Jul 2009 01:12:29 -0400

Perhaps something like this is better:

*** cal-menu.el.~1.114.~	2009-01-07 20:13:09.000000000 -0800
--- cal-menu.el	2009-07-16 22:08:54.000000000 -0700
***************
*** 202,210 ****
  
  (defun cal-menu-set-date-title (menu)
    "Convert date of last event to title suitable for MENU."
!   (easy-menu-filter-return
!    menu (calendar-date-string (calendar-cursor-to-date t last-input-event)
!                               t nil)))
  
  (easy-menu-define cal-menu-context-mouse-menu nil
    "Pop up menu for Mouse-2 for selected date in the calendar window."
--- 202,212 ----
  
  (defun cal-menu-set-date-title (menu)
    "Convert date of last event to title suitable for MENU."
!   (let ((date (ignore-errors (calendar-cursor-to-date nil last-input-event))))
!     (if date
!         (easy-menu-filter-return menu (calendar-date-string date t nil))
!       (message "Not on a date!")
!       nil)))
  
  (easy-menu-define cal-menu-context-mouse-menu nil
    "Pop up menu for Mouse-2 for selected date in the calendar window."

Message #21 received at 3862 <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Stefan Monnier <monnier <at> IRO.UMontreal.CA>
To: Glenn Morris <rgm <at> gnu.org>
Cc: 3862 <at> debbugs.gnu.org, Kevin Ryde <user42 <at> zip.com.au>
Subject: Re: bug#3862: 23.1.50; error calling `documentation' on calendar-mode
Date: Fri, 17 Jul 2009 11:58:10 -0400

> Perhaps something like this is better:

That seems OK, tho I'd rather return the menu in either case and use
some default string (e.g. "today") for the date when
calendar-cursor-to-date signals an error.


        Stefan

Message #26 received at 3862-done <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: 3862-done <at> debbugs.gnu.org
Subject: Re: bug#3862: 23.1.50; error calling `documentation' on calendar-mode
Date: Sat, 18 Jul 2009 20:37:04 -0400

  * calendar/cal-menu.el (cal-menu-set-date-title): Handle calls
  from non-calendar buffers (Bug#3862).

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