Re: Emacs21 display bug in text mode: "flashing window"

[Stefan Monnier]

>>>>> "Gerd" == Gerd Moellmann <gerd.moellmann@t-online.de> writes:
>> Split the window vertically: C-x 2 (split-window-vertically)
>> Split the window horizontally: C-x 3 (split-window-horizontally)
>> Enlarge the window: C-x ^ (enlarge-window)
[...]
> Pretty strange.  I don't see any problem here (FreeBSD 4.4).

I can't really reproduce the problem, but I guess it's just
because I build my Emacs with debugging/assertions turn on:
as soon as I do the C-x ^ Emacs crashes on an assertion failure.
The assertion is

#3  0x805675e in sync_window_with_frame_matrix_rows (w=0x861bbf8) at 
dispnew.c:3021
3021      xassert (WINDOW_FULL_WIDTH_P (w));
(gdb) p *w
$1 = {size = 536875074, vec_next = 0x861bad0, frame = 1214364368, mini_p = 
408960444, next = 1216073424, prev = 408960444, hchild = 408960444, vchild = 
408960444, parent = 1216073144, left = 0, top = 1, height = 32, width = 148, 
buffer = 1214318064, start = 677490340, pointm = 677490360, 
  force_start = 408960444, optional_new_start = 408960444, hscroll = 0, 
min_hscroll = 0, use_time = 1, sequence_number = 1, temslot = 408960444, 
last_modified = 0, last_overlay_modified = 0, last_point = 192, last_had_star = 
408960444, vertical_scroll_bar = 408960444, 
  left_margin_width = 408960444, right_margin_width = 408960444, last_mark_x = 
408960444, last_mark_y = 408960444, window_end_pos = 0, window_end_vpos = 3, 
window_end_valid = 408960444, update_mode_line = 408960492, start_at_line_beg = 
408960492, display_table = 408960444, 
  dedicated = 408960444, base_line_number = 1, base_line_pos = 1, 
region_showing = 408960444, column_number_displayed = 408960444, 
redisplay_end_trigger = 408960444, too_small_ok = 408960444, orig_height = 
408960444, orig_top = 408960444, current_matrix = 0x875dbd0, 
  desired_matrix = 0x875d980, last_cursor = {x = 0, y = 4, hpos = 0, vpos = 4}, 
cursor = {x = 0, y = 4, hpos = 0, vpos = 4}, phys_cursor = {x = 0, y = 0, hpos 
= 0, vpos = 0}, phys_cursor_type = -1, phys_cursor_ascent = 408960444, 
phys_cursor_height = 408960444, phys_cursor_on_p = 0, 
  cursor_off_p = 0, last_cursor_off_p = 0, must_be_updated_p = 1, 
pseudo_window_p = 0, vscroll = 0, window_end_bytepos = 0, frozen_window_start_p 
= 0, height_fixed_p = 0}
(gdb) p 408960444
$2 = 408960444
(gdb) xsymbol
$3 = (struct Lisp_Symbol *) 0x8603dbc
0x83253c8 "nil"

The full backtrace is appended.


        Stefan


(gdb) bt
#0  0x402baa21 in __kill () from /lib/libc.so.6
#1  0x8167507 in abort () at emacs.c:401
#2  0x402b41ed in __assert_fail (assertion=0x8297d60 "((((w)->width) + 0) == 
(((((((((enum Lisp_Type) (((((w)->frame)) >> (32 - 4)) & ((((int) 1)<<3) - 1))) 
== Lisp_Vectorlike) && (((((((((enum Lisp_Type) (((((w)->frame)) >> (32 - 4)) & 
((((int) 1)<<3) -"..., file=0x82946cf "dispnew.c", 
    line=3021, function=0x8297cc0 "sync_window_with_frame_matrix_rows") at 
assert.c:60
#3  0x805675e in sync_window_with_frame_matrix_rows (w=0x861bbf8) at 
dispnew.c:3021
#4  0x8057025 in mirror_line_dance (w=0x861bbf8, unchanged_at_top=31, nlines=5, 
copy_from=0xbfffe190, retained_p=0xbfffe180 "\001\001\001\001") at 
dispnew.c:3173
#5  0x8056b7b in mirror_line_dance (w=0x87bcdb8, unchanged_at_top=31, nlines=5, 
copy_from=0xbfffe190, retained_p=0xbfffe180 "\001\001\001\001") at 
dispnew.c:3090
#6  0x8056c37 in mirror_line_dance (w=0x87a5cb0, unchanged_at_top=31, nlines=5, 
copy_from=0xbfffe190, retained_p=0xbfffe180 "\001\001\001\001") at 
dispnew.c:3093
#7  0x80565be in mirrored_line_dance (matrix=0x875d730, unchanged_at_top=31, 
nlines=5, copy_from=0xbfffe190, retained_p=0xbfffe180 "\001\001\001\001") at 
dispnew.c:3002
#8  0x8070ac7 in do_direct_scrolling (current_matrix=0x875d730, 
cost_matrix=0xbfffe230, window_size=5, unchanged_at_top=31) at scroll.c:797
#9  0x8070b52 in scrolling_1 (frame=0x861bad0, window_size=5, 
unchanged_at_top=31, unchanged_at_bottom=29, draw_cost=0xbfffe638, 
old_draw_cost=0xbfffe528, old_hash=0xbfffe858, new_hash=0xbfffe748, 
free_at_end=5) at scroll.c:827
#10 0x805cd41 in scrolling (frame=0x861bad0) at dispnew.c:5311
#11 0x805c458 in update_frame_1 (f=0x861bad0, force_p=0, inhibit_id_p=0) at 
dispnew.c:5080
#12 0x805992b in update_frame (f=0x861bad0, force_p=0, inhibit_hairy_id_p=0) at 
dispnew.c:3837
#13 0x808a173 in redisplay_internal (preserve_echo_area=0) at xdisp.c:8810
#14 0x8087fcd in redisplay () at xdisp.c:8228
#15 0x816f4b5 in read_char (commandflag=1, nmaps=2, maps=0xbffff180, 
prev_event=408960444, used_mouse_menu=0xbffff244) at keyboard.c:2269
#16 0x81809e7 in read_key_sequence (keybuf=0xbffff3b0, bufsize=30, 
prompt=408960444, dont_downcase_last=0, can_return_switch_frame=1, 
fix_current_buffer=1) at keyboard.c:8182
#17 0x816bac7 in command_loop_1 () at keyboard.c:1437
#18 0x820d02d in internal_condition_case (bfun=0x816b1a0 <command_loop_1>, 
handlers=409056860, hfun=0x816abe4 <cmd_error>) at eval.c:1325
#19 0x816b040 in command_loop_2 () at keyboard.c:1243
#20 0x820ca44 in internal_catch (tag=409018188, func=0x816b01c 
<command_loop_2>, arg=408960444) at eval.c:1084
#21 0x816afbd in command_loop () at keyboard.c:1222
#22 0x816a57b in recursive_edit_1 () at keyboard.c:948
#23 0x816a963 in Frecursive_edit () at keyboard.c:1004
#24 0x8168c8c in main (argc=4, argv=0xbffff9a4, envp=0xbffff9b8) at emacs.c:1561
#25 0x402a9b5c in __libc_start_main (main=0x8167c20 <main>, argc=4, 
ubp_av=0xbffff9a4, init=0x804d914 <_init>, fini=0x8294668 <_fini>, 
rtld_fini=0x4000d634 <_dl_fini>, stack_end=0xbffff99c) at 
../sysdeps/generic/libc-start.c:129
(gdb)