bug#17775: 24.4.50; `ispell-command-loop` -- portion of code occasionally returns `nil`.

bug#17775: 24.4.50; `ispell-command-loop` -- portion of code occasionally returns `nil`.

[Keith David Bershatsky]

I believe that the following code snippet from `ispell.el` (which I commented out) is responsible for sporadically returning `nil` and causing the function `ispell-command-loop` to fail.  Because the issue is sporadic, I have not yet been able to catch it when running Emacs -Q.  Commenting out the code and replacing it with just `choices` appears to resolve the issue, but I'm not certain what negative affect that might have.

      (while choices
         ;; EXPERIMENTAL WITHOUT THESE CONDITIONS ***
      ;; (and choices
      ;; (< (if (> (+ 7 (current-column) (length (car choices))
      ;;        (if (> count ?~) 3 0))
      ;;     (window-width))
      ;;  (progn
      ;;    (insert "\n")
      ;;    (setq line (1+ line)))
      ;;      line)
      ;;    max-lines))

Here is a thread I opened a couple of weeks ago on Stackoverflow regarding this issue:

http://stackoverflow.com/questions/23820002/emacs-debugging-an-ispell-error

Thanks,

Keith

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In GNU Emacs 24.4.50.1 (x86_64-apple-darwin10.8.0, NS appkit-1038.36 Version 10.6.8 (Build 10K549))
 of 2014-06-01 on MP.local
Repository revision: 117215 lekktu@gmail.com-20140601162519-4dacx2w0ak528z2r
Windowing system distributor `Apple', version 10.3.1038
Configured using:
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Configured features:
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Important settings:
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Major mode: TeX

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Recent input:
o i n t l y SPC d e s i g n <backspace> <backspace> 
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a ) <left> <M-S-left> <tab> i s <s-right> , SPC t h 
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w h a t SPC " f i x t u r e s " SPC s h a l l SPC r 
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e s i d e <backspace> <backspace> <backspace> <backspace> 
<backspace> <backspace> <backspace> <backspace> <backspace> 
<backspace> <backspace> <backspace> <backspace> <backspace> 
C h e r o k e e SPC P r o <backspace> <backspace> p 
<backspace> <backspace> p r o p e r t y SPC a s SPC 
p a r t SPC o f SPC t h SPC s a l e . <M-left> <left> 
<left> <left> <left> <left> e s-s <M-left> <M-left> 
<M-left> <M-left> a n d SPC i n c l u d e d SPC <down> 
<up> <s-right> <left> SPC o f SPC t h e SPC h o e <backspace> 
m e s-s s-: a a a a a a <left> s-N s-w k <escape> x 
e m a c s SPC b u g SPC <backspace> <backspace> <backspace> 
<backspace> <backspace> <backspace> <backspace> <backspace> 
<backspace> r e p o r t - e m a c s - b u g <retur
n>

Recent messages:
Ispell process killed
Starting new Ispell process /Users/HOME/.0.data/.0.emacs/elpa/bin/aspell with english dictionary...
Turned ON `fs-mode`.
Turned ON `vl-mode`.
Type C-c C-x C-z to exit MIME mode, and type C-c C-x ? to get help.
Saving...done
Mark set
[k]ill or [s]ave draft?
Loading msgdb for +/Users/HOME/.0.data/.0.emacs/.0.mail/msgdb/imap/mail.lawlist.com/lawlist/INBOX.Drafts/spool...done
*beep*

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bug#17775: 24.4.50; `ispell-command-loop` -- portion of code occasionally returns `nil`.

[Eli Zaretskii]

> Date: Fri, 13 Jun 2014 15:43:43 -0700
> From: Keith David Bershatsky <esq@lawlist.com>
> 
> I believe that the following code snippet from `ispell.el` (which I commented out) is responsible for sporadically returning `nil` and causing the function `ispell-command-loop` to fail.  Because the issue is sporadic, I have not yet been able to catch it when running Emacs -Q.  Commenting out the code and replacing it with just `choices` appears to resolve the issue, but I'm not certain what negative affect that might have.
> 
>       (while choices
>          ;; EXPERIMENTAL WITHOUT THESE CONDITIONS ***
>       ;; (and choices
>       ;; (< (if (> (+ 7 (current-column) (length (car choices))
>       ;;        (if (> count ?~) 3 0))
>       ;;     (window-width))
>       ;;  (progn
>       ;;    (insert "\n")
>       ;;    (setq line (1+ line)))
>       ;;      line)
>       ;;    max-lines))

Do you have any evidence that this is the offending code, besides the
(maybe) fact that commenting it out makes the problem go away?  If so,
please show that evidence, because I see nothing in this snippet that
could attempt to treat nil as a number or a marker.

If there's no specific evidence that this snippet is the root cause,
then we need additional information to be able to fix this.  The code
you commented out is important (it handles the case that the number of
possible corrections of a word is more than a single line of the
window could hold), so removing it is not an option.

Here are some ways of providing the additional information:

  . provide a reproducible recipe, starting with "emacs -Q", that can
    be used to reliably reproduce the problem

  . run Emacs under GDB, set a breakpoint at xsignal2, load ispell.el
    (the source, not the .elc byte-compiled file), reproduce the
    error, then type "source /path/to/.gdbinit" at GDB prompt, and
    finally type "xbacktrace" to show the Lisp backtrace which will
    pinpoint the locus of the problem more accurately.

Thanks.

Btw, what was the width of the window when this problem happened?

> Here is a thread I opened a couple of weeks ago on Stackoverflow regarding this issue:
> 
> http://stackoverflow.com/questions/23820002/emacs-debugging-an-ispell-error

Please in the future reproduce the important part of your report here,
instead of pointing to some URL.  (I actually encourage you to report
any such problems directly here, not on Stackoverflow.  It's not like
Emacs lacks dedicated places where to report bugs.)

Here is the important part, for the benefit of others and for the
record:

> A few times each day, I receive an ispell error (like the following) that is corrected by restarting Emacs. Any ideas on how to further troubleshoot this type of error would be greatly appreciated.

> Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
>   ispell-command-loop(("Brae" "Br ea" "Br-ea" "Bra" "Bread" "Break" "Bream"
>     "Brew" "Bret" "Bred" "Area" "Urea") nil "Brea" 2229 2233)
>   ispell-process-line("^Brea, CA ~ 92821\n" nil)
>   ispell-region(1 6771)
>   ispell-buffer()
>   ispell()
>   call-interactively(ispell nil nil)
>   command-execute(ispell)

> The document being spell-checked is in tex-mode (built-in -- i.e., not using AUCTeX). The error (today) comes form a simple address at flush-left:

> 242 S. Orange Avenue\\
> Brea, CA ~ 92821

Thanks.

bug#17775: 24.4.50; `ispell-command-loop` -- portion of code occasionally returns `nil`.

[Keith David Bershatsky]

My average `(window-width)` is 168 with `linum-mode` active.   I have `visual-line-mode` active.  As to the first frame that is generated by Emacs, scroll bars are removed with code when Emacs starts -- `(modify-all-frames-parameters (list (cons 'vertical-scroll-bars nil)))` -- this ensures that my initial calling of `toggle-frame-maximized` (when Emacs loads) expands the frame to the full screen width.  As to each new frame, scroll bars are not initially present -- `(add-to-list 'default-frame-alist '(vertical-scroll-bars . nil))`.  Scroll bars are added or removed with a minor mode that calculates whether the the text is longer than the visual window -- `(set-window-scroll-bars selected-window 0 'right nil)` or `(set-window-scroll-bars selected-window 0 'right nil)`.   Scroll bar mode is now on an idle timer, but was previously on the `post-command-hook` -- the spell check error occurs sporadically in either circumstance.

My linum-mode is using a modified version of something I borrowed from Stackoverflow:

http://stackoverflow.com/a/10593165/2112489

(defun my-lawlist-linum-get-format-string ()
  (let* ((width (length (number-to-string
                             (count-lines (point-min) (point-max)))))
         (format (concat "%" (number-to-string width) "d")))
    (setq my-lawlist-linum-format-string format)))

I apologize for not writing up a better initial bug report and I'll update this bug report when I have more useful information.  You are correct in your assumption that the only evidence I have (that the code snippet caused the problem) iss that the error seems to go away by commenting it out.

Keith

---------------------------------------

On Jun 14, 2014, at 1:13 AM, Eli Zaretskii wrote:
> 
> Btw, what was the width of the window when this problem happened?

bug#17775: 24.4.50; `ispell-command-loop` -- portion of code occasionally returns `nil`.

[Lars Ingebrigtsen]

Keith David Bershatsky <esq@lawlist.com> writes:

> I apologize for not writing up a better initial bug report and I'll
> update this bug report when I have more useful information.  You are
> correct in your assumption that the only evidence I have (that the
> code snippet caused the problem) iss that the error seems to go away
> by commenting it out.

More information was requested, but no response was given within a few
months, so I'm closing this bug report.  If the problem still exists,
please reopen this bug report.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no