bug#728: 23.0.60; flyspell checking is sometimes silently disabled

bug#728: 23.0.60; flyspell checking is sometimes silently disabled

[Markus Triska]

Sometimes in flyspell-mode, the mode line still says "Fly", but no
more flychecking is actually performed. I cannot yet reproduce it
reliably; however, if you add the following to your .emacs:

   (defun my-flyspell-check ()
     (when flyspell-mode
       (unless (memq 'flyspell-post-command-hook post-command-hook)
         (with-current-buffer (get-buffer-create "flywarn")
           (insert "flychecking inactive despite flyspell-mode!\n"))
         (display-buffer  "flywarn"))))

   (setq flycheck-timer (run-with-timer 0 0.5 'my-flyspell-check))

you will be informed when flyspell mode is superficially active, but
no checking is actually performed. I only encountered the problem once
since I have the above code in my .emacs, and then I also saw:
"Invalid search bound (wrong side of point)" in *Messages*, which I
previously probably missed. Thus I think this could for example happen
when switching buffers or using the minibuffer at the wrong time.

It is clear that flyspell-post-command-hook must be removed from
post-command-hook in case of errors; if the error is hard to catch in
the hook, I would already find it an improvement if flyspell mode were
cleanly disabled (existing underlines, mode line, ...) in such cases.

In GNU Emacs 23.0.60.1 (i386-apple-darwin8.11.1, GTK+ Version 2.12.9)
 of 2008-08-15 on mt-computer.local
Windowing system distributor `The XFree86 Project, Inc', version 11.0.40400000
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.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: nil
  default-enable-multibyte-characters: t

bug#728: 23.0.60; flyspell checking is sometimes silently disabled

[Stefan Monnier]

> no checking is actually performed. I only encountered the problem once
> since I have the above code in my .emacs, and then I also saw:
> "Invalid search bound (wrong side of point)" in *Messages*, which I

You need to try and track down the porigian of this message.  It may
be due to flyspell but it can also be due to something else: if there's
a bug in one of the post-command-hooks, post-command-hook is set to nil
(hence *all* post-command-hooks are disabled).


        Stefan

bug#728: marked as done (23.0.60; flyspell checking is sometimes silently disabled)

[Emacs bug Tracking System]

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Your message dated Tue, 16 Sep 2008 20:59:57 -0400
with message-id <87fxnzr3hu.fsf@cyd.mit.edu>
and subject line Re: 23.0.60; flyspell checking is sometimes silently disabled
has caused the Emacs bug report #728,
regarding 23.0.60; flyspell checking is sometimes silently disabled
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
bug report if necessary, and/or fix the problem forthwith.

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-- 
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Emacs Bug Tracking System
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From: Markus Triska <markus.triska@gmx.at>
To: emacs-pretest-bug@gnu.org
Subject: 23.0.60; flyspell checking is sometimes silently disabled
Date: Sat, 16 Aug 2008 00:20:22 +0200 (CEST)
Message-ID: <20080815222022.E7882A30C89@mt-computer.local>


Sometimes in flyspell-mode, the mode line still says "Fly", but no
more flychecking is actually performed. I cannot yet reproduce it
reliably; however, if you add the following to your .emacs:

   (defun my-flyspell-check ()
     (when flyspell-mode
       (unless (memq 'flyspell-post-command-hook post-command-hook)
         (with-current-buffer (get-buffer-create "flywarn")
           (insert "flychecking inactive despite flyspell-mode!\n"))
         (display-buffer  "flywarn"))))

   (setq flycheck-timer (run-with-timer 0 0.5 'my-flyspell-check))

you will be informed when flyspell mode is superficially active, but
no checking is actually performed. I only encountered the problem once
since I have the above code in my .emacs, and then I also saw:
"Invalid search bound (wrong side of point)" in *Messages*, which I
previously probably missed. Thus I think this could for example happen
when switching buffers or using the minibuffer at the wrong time.

It is clear that flyspell-post-command-hook must be removed from
post-command-hook in case of errors; if the error is hard to catch in
the hook, I would already find it an improvement if flyspell mode were
cleanly disabled (existing underlines, mode line, ...) in such cases.

In GNU Emacs 23.0.60.1 (i386-apple-darwin8.11.1, GTK+ Version 2.12.9)
 of 2008-08-15 on mt-computer.local
Windowing system distributor `The XFree86 Project, Inc', version 11.0.40400000
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.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: nil
  default-enable-multibyte-characters: t




[-- Attachment #3: Type: message/rfc822, Size: 1341 bytes --]

From: Chong Yidong <cyd@stupidchicken.com>
To: Markus Triska <markus.triska@gmx.at>
Cc: 728-done@emacsbugs.donarmstrong.com
Subject: Re: 23.0.60; flyspell checking is sometimes silently disabled
Date: Tue, 16 Sep 2008 20:59:57 -0400
Message-ID: <87fxnzr3hu.fsf@cyd.mit.edu>

> The following patch fixes this problem for me:

Checked in, thanks.

bug#728: 23.0.60; flyspell checking is sometimes silently disabled

[Chong Yidong]

> Sometimes in flyspell-mode, the mode line still says "Fly", but no
> more flychecking is actually performed. I cannot yet reproduce it
> reliably

Hi Markus,

Have you found a way to track down the problem causing this bug?

bug#728: 23.0.60; flyspell checking is sometimes silently disabled

[Markus Triska]

Chong Yidong <cyd@stupidchicken.com> writes:

> Have you found a way to track down the problem causing this bug?

I have set debug-on-error to t, so the next time I see this problem, I
hope to catch which function raises the error. I already know that it is
either preview-move-point (from AUCTeX) or flyspell-post-command-hook.

Thus, especially if an AUCTeX user reads this: If you want to help to
debug this problem, please add the following to your .emacs:

   (defun my-flyspell-check ()
     (when flyspell-mode
       (unless (memq 'flyspell-post-command-hook post-command-hook)
         (with-current-buffer (get-buffer-create "flywarn")
           (insert "flychecking inactive despite flyspell-mode!\n"))
         (display-buffer  "flywarn"))))

   (setq flycheck-timer (run-with-timer 0 0.5 'my-flyspell-check))

and it will warn you when Flyspell is no longer really active.

Also, as I mentioned: I find it fair enough that Flyspell is disabled
when there are errors; I only wish that there were a general mechanism
to disable it in a cleaner way in case of errors, i.e., existing
underlines should be removed, the mode line should reflect that it is no
longer active etc. In short, when flyspell-post-command-hook must be
removed from post-command-hook, also (flyspell-mode 0) or anything
equivalent should be done. Analogously for some other modes (linum.el is
another example, where errors in a custom linum-format function should
make Emacs disable the minor mode completely, thus removing it from
other hooks as well).

bug#728: 23.0.60; flyspell checking is sometimes silently disabled

[Markus Triska]

The error occurs in flyspell-post-command-hook. To reproduce:

1) Install the latest AUCTeX (11.85), and let .emacs consist only of:

   (load "auctex.el" nil t t)

2) Let sat.tex ( http://www.logic.at/prolog/sat.tex ) consist of:

\maketitle
    \includegraphics[scale=0.8]
%       \hline
  
%   \begin{itemize}
%     \hspace{1cm}\hbox{\begin{tabular}
%       $a$ & $b$ & $c$ & $d$ \\

   without leading or trailing whitespace.

3) When you now do:

   $ emacs sat.tex -f flyspell-mode

   and press:

   M-g M-g 3 RET C-s $

   you get:

   Error in post-command-hook: (error Invalid search bound (wrong side
   of point))

   Alternatively, you can also press for example:

   C-n C-n C-p C-n C-n C-n C-n C-n C-n C-p

bug#728: 23.0.60; flyspell checking is sometimes silently disabled

[Markus Triska]

The following patch fixes this problem for me:

2008-09-14  Markus Triska  <markus.triska@gmx.at>

	* textmodes/flyspell.el (flyspell-math-tex-command-p): Always
	catch errors raised in `texmathp'.
	(flyspell-tex-math-initialized): Remove.

diff --git a/lisp/textmodes/flyspell.el b/lisp/textmodes/flyspell.el
index 47297c9..4296861 100644
--- a/lisp/textmodes/flyspell.el
+++ b/lisp/textmodes/flyspell.el
@@ -1166,35 +1166,19 @@ Mostly we check word delimiters."
 	      res))))))))
 
 ;;*---------------------------------------------------------------------*/
-;;*    flyspell-tex-math-initialized ...                                */
-;;*---------------------------------------------------------------------*/
-(defvar flyspell-tex-math-initialized nil)
-
-;;*---------------------------------------------------------------------*/
 ;;*    flyspell-math-tex-command-p ...                                  */
 ;;*    -------------------------------------------------------------    */
-;;*    This function uses the texmathp package to check if (point)      */
-;;*    is within a tex command. In order to avoid using                 */
-;;*    condition-case each time we use the variable                     */
-;;*    flyspell-tex-math-initialized to make a special case the first   */
-;;*    time that function is called.                                    */
+;;*    This function uses the texmathp package to check if point        */
+;;*    is within a TeX math environment. `texmathp' can yield errors    */
+;;*    if the document is currently not valid TeX syntax.               */
 ;;*---------------------------------------------------------------------*/
 (defun flyspell-math-tex-command-p ()
   (when (fboundp 'texmathp)
-    (cond
-     (flyspell-check-tex-math-command
-      nil)
-     ((eq flyspell-tex-math-initialized t)
-      (texmathp))
-     ((eq flyspell-tex-math-initialized 'error)
-      nil)
-     (t
-      (setq flyspell-tex-math-initialized t)
+    (if flyspell-check-tex-math-command
+        nil
       (condition-case nil
           (texmathp)
-        (error (progn
-                 (setq flyspell-tex-math-initialized 'error)
-                 nil)))))))
+        (error nil)))))
 
 ;;*---------------------------------------------------------------------*/
 ;;*    flyspell-tex-command-p ...                                       */