GNU bug report logs - #106
23.0.50; (pos-visible-in-window-p) returns error with 'before-string overlay

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

From: Yoshiaki Kasahara <kasahara <at> nc.kyushu-u.ac.jp>
To: emacs-pretest-bug <at> gnu.org
Subject: 23.0.50; (pos-visible-in-window-p) returns error with
 'before-string overlay
Date: Wed, 02 Apr 2008 02:17:17 +0900 (JST)

Please write in English if possible, because the Emacs maintainers
usually do not have translators to read other languages for them.

Your bug report will be posted to the emacs-pretest-bug <at> gnu.org mailing list.

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

When there is an overlay with 'before-string property at the beginning
of a line in a buffer, the point in the buffer is on the overlay, and
both the overlay and the point are placed at the bottom of the window,
(pos-visible-in-window-p) returns 'Args out of range: 0'.

To reproduce, insert some blank lines to *scratch* buffer, and eval
the following:

(overlay-put (make-overlay (point-max) (point-max)) 'before-string "[before-string]")

Then place the overlay and the point at the bottom of the window like
this, and eval (pos-visible-in-window-p):

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

[before-string]<- point is here
-EEJ:**--....  <- modeline
Eval: (pos-visible-in-window-p)
--------------

Currently I'm using emacs before-merge-unicode-to-trunk.  I reproduced
the same symptom in CVS HEAD (23.0.60) of today.  It doesn't happen in
emacs-21.3 (it returns t).

In some cases the emacs process starts to consume 100% CPU and doesn't
respond to keyboard-quit after the error.  I have to kill the process.
But I cannot reliably reproduce the lock-up.  Nexttime I'll try to
attach GDB to get a backtrace.

If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
If you would like to further debug the crash, please read the file
/usr/local/share/emacs/23.0.50/etc/DEBUG for instructions.


In GNU Emacs 23.0.50.2 (x86_64-unknown-freebsd7.0, X toolkit, Xaw3d scroll bars)
 of 2008-03-04 on elvenbow.cc.kyushu-u.ac.jp
configured using `configure  '--with-x-toolkit=lucid' '--without-xim' '--without-gtk''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: ja_JP.eucJP
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: C
  value of $LANG: ja_JP.eucJP
  locale-coding-system: japanese-iso-8bit
  default-enable-multibyte-characters: t

Major mode: Apropos

Minor modes in effect:
  show-paren-mode: t
  iswitchb-mode: t
  icomplete-mode: t
  display-time-mode: t
  shell-dirtrack-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t

Message #10 received at 106 <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Yoshiaki Kasahara <kasahara <at> nc.kyushu-u.ac.jp>
To: 106 <at> debbugs.gnu.org
Subject: Re: 23.0.50; (pos-visible-in-window-p) returns error with
 'before-string overlay
Date: Thu, 03 Apr 2008 12:14:34 +0900 (JST)

On Wed, 02 Apr 2008 02:17:17 +0900 (JST),
	Yoshiaki Kasahara <kasahara <at> nc.kyushu-u.ac.jp> said:

> In some cases the emacs process starts to consume 100% CPU and doesn't
> respond to keyboard-quit after the error.  I have to kill the process.
> But I cannot reliably reproduce the lock-up.  Nexttime I'll try to
> attach GDB to get a backtrace.

I found a reliable way to reproduce the lock-up (an infinite loop
somewhere).  The lock-up always happens when I have both X and tty
frames (I'm a fan of the multi-tty functionality).  Even the lock-up
occurs when I connect to the emacs-server from a tty using
'emacsclient -t' *after* the "args-out-of-range" error.

I tried to collect the backtrace, but I'm not sure if it is really
meaningful or not.

[Switching to Thread 0xb23000 (LWP 100485)]
0x0000000000432693 in move_it_in_display_line_to (it=0x7fffffffaa60, 
    to_charpos=18001, to_x=-1, op=Variable "op" is not available.
) at xdisp.c:6675
6675                  else if (BUFFER_POS_REACHED_P ())
DISPLAY = :0.0
TERM = rxvt
Breakpoint 1 at 0x4aed40: file emacs.c, line 431.
Breakpoint 2 at 0x4c9770: file sysdep.c, line 1320.
(gdb) xbacktrace
(gdb) bt full
#0  0x0000000000432693 in move_it_in_display_line_to (it=0x7fffffffaa60, 
    to_charpos=18001, to_x=-1, op=Variable "op" is not available.
) at xdisp.c:6675
        new_x = 71
        hpos_before_this_char = 69
        x = 70
        i = 1
        ascent = 0
        descent = 0
        result = Variable "result" is not available.
(gdb) bt
#0  0x0000000000432693 in move_it_in_display_line_to (it=0x7fffffffaa60, 
    to_charpos=18001, to_x=-1, op=Variable "op" is not available.
) at xdisp.c:6675
#1  0x0000000000434c8f in move_it_to (it=0x7fffffffaa60, to_charpos=18001, 
    to_x=-1, to_y=-1, to_vpos=-1, op=8) at xdisp.c:6897
#2  0x000000000043bd4d in move_it_vertically_backward (it=0x7fffffffc270, 
    dy=10) at xdisp.c:7004
#3  0x00000000004401f1 in redisplay_window (window=38673412, just_this_one_p=0)
    at xdisp.c:13404
#4  0x00000000004431e1 in redisplay_window_0 (window=1) at xdisp.c:11901
#5  0x000000000051a1c8 in internal_condition_case_1 (
    bfun=0x4431c0 <redisplay_window_0>, arg=38673412, handlers=9474869, 
    hfun=0x41f330 <redisplay_window_error>) at eval.c:1542
#6  0x000000000042f015 in redisplay_windows (window=Variable "window" is not available.
) at xdisp.c:11880
#7  0x00000000004437f5 in redisplay_internal (preserve_echo_area=Variable "preserve_echo_area" is not available.
)
    at xdisp.c:11437
#8  0x00000000004bb729 in read_char (commandflag=1, nmaps=4, 
    maps=0x7fffffffd7b0, prev_event=9496577, used_mouse_menu=0x7fffffffd8f0, 
    end_time=0x0) at keyboard.c:2724
#9  0x00000000004be135 in read_key_sequence (keybuf=0x7fffffffd960, 
    bufsize=30, prompt=9496577, dont_downcase_last=0, 
    can_return_switch_frame=1, fix_current_buffer=1) at keyboard.c:9460
#10 0x00000000004bff8b in command_loop_1 () at keyboard.c:1655
#11 0x000000000051a45f in internal_condition_case (
    bfun=0x4bfde0 <command_loop_1>, handlers=9635105, 
    hfun=0x4b9d00 <cmd_error>) at eval.c:1494
#12 0x00000000004b90ea in command_loop_2 () at keyboard.c:1370
#13 0x000000000051a577 in internal_catch (tag=Variable "tag" is not available.
) at eval.c:1230
#14 0x00000000004b9b43 in command_loop () at keyboard.c:1349
#15 0x00000000004b9edc in recursive_edit_1 () at keyboard.c:958
#16 0x00000000004ba041 in Frecursive_edit () at keyboard.c:1020
#17 0x00000000004afa4a in main (argc=7, argv=0x7fffffffdde0) at emacs.c:1743
(gdb)

-- 
Yoshiaki Kasahara
Research Institute for Information Technology, Kyushu University
kasahara <at> nc.kyushu-u.ac.jp

Message #15 received at 106-done <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Chong Yidong <cyd <at> stupidchicken.com>
To: Yoshiaki Kasahara <kasahara <at> nc.kyushu-u.ac.jp>
Cc: 106-done <at> debbugs.gnu.org
Subject: Re: 23.0.50; (pos-visible-in-window-p) returns error with 'before-string overlay
Date: Sun, 20 Apr 2008 18:42:59 -0400

I've checked in a fix into CVS.  Thanks for the bug report.

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