From: Chong Yidong <cyd@stupidchicken.com>
Cc: kifer@cs.sunysb.edu, emacs-devel@gnu.org
Subject: Re: [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil]
Date: Tue, 15 Aug 2006 19:19:04 -0400 [thread overview]
Message-ID: <877j19lh93.fsf@stupidchicken.com> (raw)
In-Reply-To: <E1GAz72-0002m1-E1@fencepost.gnu.org> (Richard Stallman's message of "Wed, 09 Aug 2006 21:13:28 -0400")
> 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
next prev parent reply other threads:[~2006-08-15 23:19 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-10 1:13 [kzeitler@sfsws1.de.lucent.com: Buffer sometimes changes to modified with truncate-partial-width-windows set to nil] Richard Stallman
2006-08-10 22:50 ` Chong Yidong
2006-08-11 6:50 ` Klaus Zeitler
2006-08-11 19:23 ` Richard Stallman
2006-08-15 23:19 ` Chong Yidong [this message]
2006-08-16 7:50 ` martin rudalics
2006-08-16 11:55 ` Klaus Zeitler
2006-08-16 12:51 ` martin rudalics
2006-08-16 14:07 ` Chong Yidong
2006-08-17 6:19 ` Klaus Zeitler
2006-08-17 15:07 ` Stefan Monnier
2006-08-17 15:19 ` Richard Stallman
2006-08-25 20:23 ` Richard Stallman
2006-08-26 0:03 ` Stefan Monnier
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