bug#11417: 24.0.96; infinite looping in xdisp.c

[Leo <sdl.web@gmail.com>]

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On 2012-05-07 00:18 +0800, Eli Zaretskii wrote:
> First, please provide the entire backtrace from here to main, and also
> the Lisp backtrace (from the "xbacktrace" command).  You will need to
> make sure GDB reads the src/.gdbinit file for "xbacktrace" to work,
> and also for several other commands below.

I built it from emacs-24 branch.

I run gdb in emacs/src and attach to the process that is hanging. Then
source .gdbinit and I got:

DISPLAY = /tmp/launch-VtT4mU/org.x:0
TERM = xterm-color
[0] cancel
[1] all

Non-debugging symbols:
[2]    -[CIContext abort]
[3]    -[CIContextImpl abort]
[4]    abort
> Argument required (one or more choice numbers).
Breakpoint 1 at 0x100156fcf: file sysdep.c, line 859.

So commands such as xbt, xtype and pgrowx not working properly. The rest
is as attached. The portion of the line from it2.current should show:

from distutils.core import setup, Extension 


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(gdb) bt
#0  move_it_vertically_backward (it=0x7fff5fbfce20, dy=0) at xdisp.c:8804
#1  0x00000001000409ad in move_it_by_lines (it=0x7fff5fbfce20, dvpos=0) at xdisp.c:8985
#2  0x00000001001a0ce7 in Fvertical_motion (lines=0, window=4305481917) at indent.c:2087
#3  0x000000010009ddb8 in window_scroll_line_based (window=4305481917, n=43, whole=1, noerror=0) at window.c:4667
#4  0x000000010009c251 in window_scroll (window=4305481917, n=1, whole=1, noerror=0) at window.c:4204
#5  0x000000010009e138 in scroll_command (n=4320145466, direction=1) at window.c:4758
#6  0x000000010009e1ff in Fscroll_up (arg=4320145466) at window.c:4779
#7  0x0000000100204987 in Ffuncall (nargs=2, args=0x7fff5fbfde90) at eval.c:3002
#8  0x0000000100272e01 in exec_byte_code (bytestr=4299304921, vector=4299304957, maxdepth=12, args_template=4320145466, nargs=0, args=0x0) at bytecode.c:785
#9  0x0000000100205868 in funcall_lambda (fun=4299304861, nargs=1, arg_vector=0x7fff5fbfe528) at eval.c:3233
#10 0x0000000100204d89 in Ffuncall (nargs=2, args=0x7fff5fbfe520) at eval.c:3051
#11 0x00000001001fc548 in Fcall_interactively (function=4320366570, record_flag=4320145466, keys=4305468733) at callint.c:852
#12 0x0000000100204a0b in Ffuncall (nargs=4, args=0x7fff5fbfead8) at eval.c:3009
#13 0x0000000100203e39 in call3 (fn=4320271882, arg1=4320366570, arg2=4320145466, arg3=4320145466) at eval.c:2802
#14 0x00000001001433a9 in Fcommand_execute (cmd=4320366570, record_flag=4320145466, keys=4320145466, special=4320145466) at keyboard.c:10451
#15 0x000000010012adf5 in command_loop_1 () at keyboard.c:1620
#16 0x0000000100200155 in internal_condition_case (bfun=0x10012a300 <command_loop_1>, handlers=4320201674, hfun=0x100129800 <cmd_error>) at eval.c:1515
#17 0x0000000100129df8 in command_loop_2 (ignore=4320145466) at keyboard.c:1189
#18 0x00000001001ff985 in internal_catch (tag=4320197690, func=0x100129dc0 <command_loop_2>, arg=4320145466) at eval.c:1272
#19 0x0000000100129d77 in command_loop () at keyboard.c:1159
#20 0x0000000100129189 in recursive_edit_1 () at keyboard.c:766
#21 0x00000001001293d0 in Frecursive_edit () at keyboard.c:830
#22 0x0000000100126c78 in main (argc=3, argv=0x7fff5fbff638) at emacs.c:1739
(gdb) p start_pos
$5 = 411
(gdb) p it2.vpos
$6 = 0
(gdb) p it2.current
$7 = {
  pos = {
    charpos = 411, 
    bytepos = 411
  }, 
  overlay_string_index = 0, 
  string_pos = {
    charpos = 1, 
    bytepos = 1
  }, 
  dpvec_index = -1
}
(gdb) p it2.string
$8 = 4334846993
(gdb) xtype
Undefined command: "xtype".  Try "help".
(gdb) p it2.method
$9 = GET_FROM_STRING

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> Second, I need to see some of the variables involved in this:
>
>  (gdb) p start_pos
>  (gdb) p it2.vpos
>  (gdb) p it2.current
>  (gdb) p it2.string
>  (gdb) xtype
>  (gdb) p it2.method
>
> Finally, can you describe what should be displayed on the portion of
> the screen that is around the character position (shown by "p it2.current"
> above) where Emacs loops?  The following command should display
> detailed information about the screen line that includes the above buffer
> position:
>
>  (gdb) pgrowx (it2.w->desired_matrix->rows+N)
>
> where N is the zero-based number of the screen line.  If you cannot
> easily figure out the value of N, try the above command for successive
> values starting from zero, until you see the first screen line that is
> not displayed.
>
> Thanks.

Thanks.