bug#26980: 25.2; Freeze & redisplay_internal & macOS

[Eli Zaretskii <eliz@gnu.org>]

> From: Robert Vojta <rvojta@me.com>
> Date: Fri, 19 May 2017 12:27:19 +0200
> Cc: Alan Third <alan@idiocy.org>, 26980@debbugs.gnu.org
> 
> (lldb) attach 72569
> Process 72569 stopped
> * thread #1: tid = 0x68a63f, 0x000000010035e403 Emacs`lookup_char_property(plist=4369609187, prop=13392, textprop=true) + 131 at intervals.c:1760, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
>     frame #0: 0x000000010035e403 Emacs`lookup_char_property(plist=4369609187, prop=13392, textprop=true) + 131 at intervals.c:1760
>    1757	      tem = XCAR (tail);
>    1758	      if (EQ (prop, tem))
>    1759		return Fcar (XCDR (tail));
> -> 1760	      if (EQ (tem, Qcategory))
>    1761		{
>    1762		  tem = Fcar (XCDR (tail));
>    1763		  if (SYMBOLP (tem))
> 
> 
> (lldb) thread backtrace
> * thread #1: tid = 0x68a63f, 0x000000010035e403 Emacs`lookup_char_property(plist=4369609187, prop=13392, textprop=true) + 131 at intervals.c:1760, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
>   * frame #0: 0x000000010035e403 Emacs`lookup_char_property(plist=4369609187, prop=13392, textprop=true) + 131 at intervals.c:1760
>     frame #1: 0x000000010035e372 Emacs`textget(plist=4369609187, prop=13392) + 34 at intervals.c:1746
>     frame #2: 0x0000000100364c5b Emacs`Fnext_single_property_change(position=19506, prop=13392, object=4621909941, limit=21506) + 379 at textprop.c:1027
>     frame #3: 0x000000010036ceec Emacs`find_composition(pos=4876, limit=5376, start=0x00007fff5fbf65c0, end=0x00007fff5fbf65b8, prop=0x00007fff5fbf65a8, object=0) + 204 at composite.c:434
>     frame #4: 0x000000010036e662 Emacs`composition_compute_stop_pos(cmp_it=0x00007fff5fbf8950, charpos=4876, bytepos=4876, endpos=5376, string=0) + 338 at composite.c:979
>     frame #5: 0x00000001000800fc Emacs`compute_stop_pos(it=0x00007fff5fbf80d0) + 1212 at xdisp.c:3554
>     frame #6: 0x000000010007f099 Emacs`handle_stop(it=0x00007fff5fbf80d0) + 665 at xdisp.c:3452
>     frame #7: 0x0000000100084a2d Emacs`next_element_from_buffer(it=0x00007fff5fbf80d0) + 621 at xdisp.c:8352
>     frame #8: 0x000000010003b4a8 Emacs`get_next_display_element(it=0x00007fff5fbf80d0) + 56 at xdisp.c:6948
>     frame #9: 0x000000010005ac19 Emacs`display_line(it=0x00007fff5fbf80d0, cursor_vpos=24) + 1065 at xdisp.c:20809
>     frame #10: 0x000000010005a529 Emacs`try_window(window=4361665229, pos=(charpos = 4022, bytepos = 4022), flags=0) + 249 at xdisp.c:17457
>     frame #11: 0x000000010008f1a9 Emacs`redisplay_window(window=4361665229, just_this_one_p=false) + 3977 at xdisp.c:16647
>     frame #12: 0x000000010008e20d Emacs`redisplay_window_0(window=4361665229) + 61 at xdisp.c:14664
>     frame #13: 0x000000010028725a Emacs`internal_condition_case_1(bfun=(Emacs`redisplay_window_0 at xdisp.c:14662), arg=4361665229, handlers=4337042083, hfun=(Emacs`redisplay_window_error at xdisp.c:14655)) + 138 at eval.c:1350
>     frame #14: 0x000000010008c7fb Emacs`redisplay_windows(window=4361665229) + 187 at xdisp.c:14644
>     frame #15: 0x000000010008c7aa Emacs`redisplay_windows(window=4361664733) + 106 at xdisp.c:14638
>     frame #16: 0x000000010005712e Emacs`redisplay_internal + 6270 at xdisp.c:14134
>     frame #17: 0x0000000100058a19 Emacs`redisplay + 9 at xdisp.c:13362
>     frame #18: 0x0000000100181735 Emacs`read_char(commandflag=1, map=4870821907, prev_event=0, used_mouse_menu=0x00007fff5fbff337, end_time=0x0000000000000000) + 1829 at keyboard.c:2482

Thanks.  Can you now use the methodology described in etc/DEBUG under
"If the symptom of the bug is that Emacs fails to respond" to try to
establish where it is looping?