[kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[Richard Stallman]

This bug is important to fix.  It probably has to do with the recent
font-lock changes.  Would someone please start working on it?

------- Start of forwarded message -------
Date: Wed, 9 Aug 2006 12:23:43 +0200 (MEST)
From: Klaus Zeitler <kzeitler@sfsws1.de.lucent.com>
To: emacs-pretest-bug@gnu.org
Subject: Buffer sometimes changes to modified with
	truncate-partial-width-windows set to nil
X-Spam-Status: No, score=0.0 required=5.0 tests=none autolearn=failed 
	version=3.0.4

1. start emacs -Q
2. in scratch buffer evaluate the following 2 expressions
(setq ediff-split-window-function 'split-window-horizontally)
(setq truncate-partial-width-windows nil)
3. M-x ediff-files file1 file2

Now when I move (with <n> in Ediff Control Panel) from diff to diff, it's
only a matter of time till at least one of the buffers changes the
buffer-modified flag without any apparent reason.



In GNU Emacs 22.0.50.7 (sparc-sun-solaris2.8, Motif Version 2.1.0)
 of 2006-08-09 on sfsws4
X server distributor `Sun Microsystems, Inc.', version 11.0.6410
configured using `configure '--with-gcc' '--prefix=/vol/freeware/SunOS-5.8/emacs/cvs' '--sharedstatedir=/vol/freeware/SunOS-5.8/emacs/cvs/share' '--with-x-toolkit=motif' '--x-includes=/usr/openwin/include:/usr/local/gnu/include:/opt/exp/gnu/include:/opt/exp/include:/opt/exp/lib/xpm/include' '--x-libraries=/usr/openwin/lib:/usr/local/gnu/lib:/opt/exp/gnu/lib:/opt/exp/lib:/opt/exp/lib/xpm/lib' '--with-pop' 'CC=gcc''

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: C
  locale-coding-system: nil
  default-enable-multibyte-characters: t

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  tool-bar-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  auto-compression-mode: t
  line-number-mode: t

Recent input:
<help-echo> <help-echo> <help-echo> <menu-bar> <help-menu> 
<report-emacs-bug>

Recent messages:
(/usr/local/gnu/cvs/head/bin/emacs -Q)
For information about the GNU Project and its goals, type C-h C-p.
Loading emacsbug...
Loading regexp-opt...done
Loading emacsbug...done


_______________________________________________
emacs-pretest-bug mailing list
emacs-pretest-bug@gnu.org
http://lists.gnu.org/mailman/listinfo/emacs-pretest-bug
------- End of forwarded message -------

Re: [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[Chong Yidong]

Richard Stallman <rms@gnu.org> writes:

> This bug is important to fix.  It probably has to do with the recent
> font-lock changes.  Would someone please start working on it?

I think Stefan fixed this already.

2006-08-02  Stefan Monnier  <monnier@iro.umontreal.ca>

	* jit-lock.el (jit-lock-fontify-now): Preserve the buffer's
	modification status when forcing the second redisplay.


> From: Klaus Zeitler <kzeitler@sfsws1.de.lucent.com>
> Subject: Buffer sometimes changes to modified with
> 	truncate-partial-width-windows set to nil
> To: emacs-pretest-bug@gnu.org
>
> 1. start emacs -Q
> 2. in scratch buffer evaluate the following 2 expressions
> (setq ediff-split-window-function 'split-window-horizontally)
> (setq truncate-partial-width-windows nil)
> 3. M-x ediff-files file1 file2
>
> Now when I move (with <n> in Ediff Control Panel) from diff to diff, it's
> only a matter of time till at least one of the buffers changes the
> buffer-modified flag without any apparent reason.
>
>
>
> In GNU Emacs 22.0.50.7 (sparc-sun-solaris2.8, Motif Version 2.1.0)
>  of 2006-08-09 on sfsws4
> X server distributor `Sun Microsystems, Inc.', version 11.0.6410
> configured using `configure '--with-gcc' '--prefix=/vol/freeware/SunOS-5.8/emacs/cvs' '--sharedstatedir=/vol/freeware/SunOS-5.8/emacs/cvs/share' '--with-x-toolkit=motif' '--x-includes=/usr/openwin/include:/usr/local/gnu/include:/opt/exp/gnu/include:/opt/exp/include:/opt/exp/lib/xpm/include' '--x-libraries=/usr/openwin/lib:/usr/local/gnu/lib:/opt/exp/gnu/lib:/opt/exp/lib:/opt/exp/lib/xpm/lib' '--with-pop' 'CC=gcc''
>
> 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: C
>   locale-coding-system: nil
>   default-enable-multibyte-characters: t
>
> Major mode: Lisp Interaction
>
> Minor modes in effect:
>   tooltip-mode: t
>   tool-bar-mode: t
>   mouse-wheel-mode: t
>   menu-bar-mode: t
>   file-name-shadow-mode: t
>   global-font-lock-mode: t
>   font-lock-mode: t
>   blink-cursor-mode: t
>   unify-8859-on-encoding-mode: t
>   utf-translate-cjk-mode: t
>   auto-compression-mode: t
>   line-number-mode: t
>
> Recent input:
> <help-echo> <help-echo> <help-echo> <menu-bar> <help-menu> 
> <report-emacs-bug>
>
> Recent messages:
> (/usr/local/gnu/cvs/head/bin/emacs -Q)
> For information about the GNU Project and its goals, type C-h C-p.
> Loading emacsbug...
> Loading regexp-opt...done
> Loading emacsbug...done
>
>
> _______________________________________________
> emacs-pretest-bug mailing list
> emacs-pretest-bug@gnu.org
> http://lists.gnu.org/mailman/listinfo/emacs-pretest-bug
> ----------
>
>
>
> _______________________________________________
> Emacs-devel mailing list
> Emacs-devel@gnu.org
> http://lists.gnu.org/mailman/listinfo/emacs-devel

Re: [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[Klaus Zeitler]

>>>>> "Chong" == Chong Yidong <cyd@stupidchicken.com> writes:
    Chong> 
    Chong> I think Stefan fixed this already.
    Chong> 
    Chong> 2006-08-02  Stefan Monnier  <monnier@iro.umontreal.ca>
    Chong> 
    Chong> 	* jit-lock.el (jit-lock-fontify-now): Preserve the buffer's
    Chong> 	modification status when forcing the second redisplay.

No, it's still there. I can reproduce it easily.

Klaus

-- 
 ------------------------------------------
|  Klaus Zeitler      Lucent Technologies  |
|  Email:             kzeitler@lucent.com  |
 ------------------------------------------
---
In any formula, constants (especially those obtained
from handbooks) are to be treated as variables.

Re: [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[Richard Stallman]

Thanks.  Would someone please DTRT and ack this message?

Re: [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[Chong Yidong]

> From: Klaus Zeitler <kzeitler@sfsws1.de.lucent.com>
> Subject: Buffer sometimes changes to modified with
> 	truncate-partial-width-windows set to nil
>
> 1. start emacs -Q
> 2. in scratch buffer evaluate the following 2 expressions
> (setq ediff-split-window-function 'split-window-horizontally)
> (setq truncate-partial-width-windows nil)
> 3. M-x ediff-files file1 file2
>
> Now when I move (with <n> in Ediff Control Panel) from diff to diff, it's
> only a matter of time till at least one of the buffers changes the
> buffer-modified flag without any apparent reason.

This seems to be an effect of the "orig-start" code that Stefan added
to `jit-lock-fontify-now'.  The problem goes away if this chunk is
commented out.  I don't know why the chunk has the effect, though; as
far as I can tell, it ought to preserve buffer modification status
since everything is wrapped in a `with-buffer-prepared-for-jit-lock'
macro.  I can confirm that `buffer-modified-p' is nil when the timer
function is run:

     ;; The redisplay engine has already rendered the buffer up-to
     ;; `orig-start' and won't notice if the above jit-lock-functions
     ;; changed the appearance of any part of the buffer prior
     ;; to that.  So if `start' is before `orig-start', we need to
     ;; cause a new redisplay cycle after this one so that any changes
     ;; are properly reflected on screen.
     ;; To make such repeated redisplay happen less often, we can
     ;; eagerly extend the refontified region with
     ;; jit-lock-after-change-extend-region-functions.
     (when (< start orig-start)
       (lexical-let ((start start)
                     (orig-start orig-start)
                     (buf (current-buffer)))
         (run-with-timer
          0 nil (lambda ()
                  (with-buffer-prepared-for-jit-lock
                      (put-text-property start orig-start
                                         'fontified t buf))))))

Even more bizaarely, tweaking set-buffer-modified-p inside the
`with-buffer-prepared-for-jit-lock' block, as shown below, also causes
the bug to go away.  By right, it should do nothing.  The
set-buffer-modified-p call can be put later in `jit-lock-fontify-now',
but putting it any earlier causes the bug to resurface.  Anyone have
any idea what's going on here?

*** emacs/lisp/jit-lock.el.~1.53.~	2006-08-15 18:27:36.000000000 -0400
--- emacs/lisp/jit-lock.el	2006-08-15 19:16:50.000000000 -0400
***************
*** 368,373 ****
--- 368,375 ----
  	   ;; We mark it first, to make sure that we don't indefinitely
  	   ;; re-execute this fontification if an error occurs.
  	   (put-text-property start next 'fontified t)
+ 	   (set-buffer-modified-p nil)
+ 
  	   (condition-case err
  	       (run-hook-with-args 'jit-lock-functions start next)
  	     ;; If the user quits (which shouldn't happen in normal on-the-fly

Re: [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[martin rudalics]

 > Even more bizaarely, tweaking set-buffer-modified-p inside the
 > `with-buffer-prepared-for-jit-lock' block, as shown below, also causes
 > the bug to go away.  By right, it should do nothing.  The
 > set-buffer-modified-p call can be put later in `jit-lock-fontify-now',
 > but putting it any earlier causes the bug to resurface.  Anyone have
 > any idea what's going on here?

Would the following handle it?

*** jit-lock.el.~1.53.~	Tue Aug 15 10:00:50 2006
--- jit-lock.el	Wed Aug 16 09:40:26 2006
***************
*** 391,399 ****
                              (buf (current-buffer)))
                  (run-with-timer
                   0 nil (lambda ()
!                         (with-buffer-prepared-for-jit-lock
!                             (put-text-property start orig-start
!                                                'fontified t buf))))))

   	   ;; Find the start of the next chunk, if any.
   	   (setq start (text-property-any next end 'fontified nil))))))))
--- 391,400 ----
                              (buf (current-buffer)))
                  (run-with-timer
                   0 nil (lambda ()
! 			(with-current-buffer buf
! 			  (with-buffer-prepared-for-jit-lock
! 			   (put-text-property start orig-start
! 					      'fontified t)))))))

   	   ;; Find the start of the next chunk, if any.
   	   (setq start (text-property-any next end 'fontified nil))))))))

Re: [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[Klaus Zeitler]

>>>>> "martin" == martin rudalics <rudalics@gmx.at> writes:
    martin> 
    martin> Would the following handle it?

No it's still the same.

Klaus

-- 
 ------------------------------------------
|  Klaus Zeitler      Lucent Technologies  |
|  Email:             kzeitler@lucent.com  |
 ------------------------------------------
---
The Abrams' Principle:
 The shortest distance between two points is off the wall.

Re: [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[martin rudalics]

 >     martin> Would the following handle it?
 >
 > No it's still the same.

Could you please verify whether the scenario described by Chong _is_
responsible for the buffer modification you see.  Try to set a
breakpoint somwhere within the

            (when (< start orig-start)

form in jit-lock.el or insert an according message.  The values of
`start', `orig-start', and `next' would interest me.

martin

Re: [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[Chong Yidong]

martin rudalics <rudalics@gmx.at> writes:

> Would the following handle it?
>
>                  (run-with-timer
>                   0 nil (lambda ()
> ! 			(with-current-buffer buf
> ! 			  (with-buffer-prepared-for-jit-lock
> ! 			   (put-text-property start orig-start
> ! 					      'fontified t)))))))

Yes!  Thanks very much for finding the problem.


Klaus Zeitler <kzeitler@lucent.com> writes:

> No it's still the same.

Did you recompile Emacs?  jit-lock.el is loaded before dumping, so if
you want changes in that file to show up, you have to do a `make'
after byte compiling it.

Re: [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[Klaus Zeitler]

>>>>> "Chong" == Chong Yidong <cyd@stupidchicken.com> writes:
    Chong> 
    Chong> Did you recompile Emacs?  jit-lock.el is loaded before dumping, so if
    Chong> you want changes in that file to show up, you have to do a `make'
    Chong> after byte compiling it.

Oops, didn't think of that. At least I thought of byte compiling it :-).
And you're right the bug is gone. Tried it a few times, no more inadvertent 
changes of the modified flag.
Thanks to Martin and Chong. 

Klaus

-- 
 ------------------------------------------
|  Klaus Zeitler      Lucent Technologies  |
|  Email:             kzeitler@lucent.com  |
 ------------------------------------------
---
If all else fails, immortality can always be assured
by spectacular error.      -- John Kenneth Galbraith

Re: [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[Stefan Monnier]

> !                         (with-buffer-prepared-for-jit-lock
> !                             (put-text-property start orig-start
> !                                                'fontified t buf))))))
> --- 391,400 ----
> ! 			(with-current-buffer buf
> ! 			  (with-buffer-prepared-for-jit-lock
> ! 			   (put-text-property start orig-start
> ! 					      'fontified t)))))))

Thanks once more for fixing my sloppy code,


        Stefan

Re: [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[Richard Stallman]

    > 1. start emacs -Q
    > 2. in scratch buffer evaluate the following 2 expressions
    > (setq ediff-split-window-function 'split-window-horizontally)
    > (setq truncate-partial-width-windows nil)
    > 3. M-x ediff-files file1 file2
    >
    > Now when I move (with <n> in Ediff Control Panel) from diff to diff, it's
    > only a matter of time till at least one of the buffers changes the
    > buffer-modified flag without any apparent reason.

    This seems to be an effect of the "orig-start" code that Stefan added
    to `jit-lock-fontify-now'.  The problem goes away if this chunk is
    commented out.

Stefan, are you going to fix this?

Re: [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[Richard Stallman]

Is this fixed now?

    > 1. start emacs -Q
    > 2. in scratch buffer evaluate the following 2 expressions
    > (setq ediff-split-window-function 'split-window-horizontally)
    > (setq truncate-partial-width-windows nil)
    > 3. M-x ediff-files file1 file2
    >
    > Now when I move (with <n> in Ediff Control Panel) from diff to diff, it's
    > only a matter of time till at least one of the buffers changes the
    > buffer-modified flag without any apparent reason.

    This seems to be an effect of the "orig-start" code that Stefan added
    to `jit-lock-fontify-now'.  The problem goes away if this chunk is
    commented out.

Re: [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]

[Stefan Monnier]

> Is this fixed now?

AFAIK: yes.


        Stefan


>> 1. start emacs -Q
>> 2. in scratch buffer evaluate the following 2 expressions
>> (setq ediff-split-window-function 'split-window-horizontally)
>> (setq truncate-partial-width-windows nil)
>> 3. M-x ediff-files file1 file2
>> 
>> Now when I move (with <n> in Ediff Control Panel) from diff to diff, it's
>> only a matter of time till at least one of the buffers changes the
>> buffer-modified flag without any apparent reason.

>     This seems to be an effect of the "orig-start" code that Stefan added
>     to `jit-lock-fontify-now'.  The problem goes away if this chunk is
>     commented out.