> 2021/05/30 5:32、Eli Zaretskii <eliz@gnu.org>のメール:
> 
>> From: Naofumi Yasufuku <naofumi@yasufuku.dev>
>> Date: Sun, 30 May 2021 04:28:11 +0900
>> 
>> After changes for auto-composition aware string-width (*),
>> emacs segfaults frequently on startup under macOS.
>> 
>> gdb 'bt full’ is attached:
>>  emacs_crash-lisp_string_width-gdb_bt_full.txt
>>  emacs_crash-lisp_string_width-macOS_report.txt
>> 
>> On my machine, crash occurrence frequency can be increased with
>> attached init.el.  Unfortunately, I cannot reproduce the crash with
>> `--enable-checking='yes,glyphs' --enable-check-lisp-object-type`
>> configure options.
>> 
>> Sometimes emacs starts without crash, but font setting is corrupted
>> like the attached screenshot: after-lisp_string_width-autocmp.png
> 
> I cannot reproduce using your init.el.
> 
>> (gdb) p sym
>> $1 = (Lisp_Object) 0x104621ba0
>> (gdb) p XSYMBOL(sym)
>> [New Thread 0x1b1f of process 79812]
>> [New Thread 0x2a03 of process 79812]
>> $2 = (struct Lisp_Symbol *) 0x204e4a730
>> (gdb) p XSYMBOL(sym)->u
>> Cannot access memory at address 0x204e4a730
>> (gdb) p XSYMBOL(sym)->u.s
>> Cannot access memory at address 0x204e4a730
>> (gdb) p XSYMBOL(sym)->u.s.name
>> Cannot access memory at address 0x204e4a738
> 
> So it's some kind of invalid "symbol".
> 
>> (gdb) up
>> #2  0x00000001002976de in font_select_entity (f=0x10433f230,
>>    entities=0x1048cb913, attrs=0x103778800, pixel_size=12, c=-1)
>>    at font.c:3159
>> 3159	    FONT_SET_STYLE (prefer, FONT_WIDTH_INDEX, attrs[LFACE_SWIDTH_INDEX]);
>> (gdb) up
>> #3  0x00000001002971b9 in font_find_for_lface (f=0x10433f230,
>>    attrs=0x103778800, spec=0x10422c7ed, c=-1) at font.c:3302
>> 3302			      val = font_select_entity (f, entities,
> 
> What is 'spec' in this frame?
> 
>  (gdb) pp spec
> 
>> (gdb) up
>> #4  0x000000010033905e in fontset_find_font (fontset=0x104419835, c=1603,
>>    face=0x103778800, charset_id=-1, fallback=false) at fontset.c:660
>> 660		  font_entity = font_find_for_lface (f, face->lface,
> 
> What is 'fontset' in this frame?
> 
>> #8  0x0000000100324fce in autocmp_chars (rule=0x105f2311d, charpos=308,
>>    bytepos=334, limit=312, win=0x104342e20, face=0x0, string=0x1033e79c4,
>>    direction=0x0) at composite.c:923
>> 923	      font_object = font_range (charpos, bytepos, &to, win, face, string);
>> (gdb) up
>> #9  0x0000000100325f1d in find_automatic_composition (pos=308, limit=308,
>>    start=0x7ffeefbf15a8, end=0x7ffeefbf15a0, gstring=0x7ffeefbf15b8,
>>    string=0x1033e79c4) at composite.c:1612
>> 1612			  *gstring = autocmp_chars (elt, check.pos, check.pos_byte,
>> (gdb) up
>> #10 0x00000001001248c8 in lisp_string_width (string=0x1033e79c4, from=0,
>>    to=479, precision=-1, nchars=0x7ffeefbf1a28, nbytes=0x7ffeefbf1a20)
>>    at character.c:375
>> 375		       && find_automatic_composition (i, -1, &ignore, &end, &val, string)
> 
> This seems to indicate Emacs is asking string-width to compute width
> of a string that has 479 characters?  How come we have such a long
> string here?
> 
>  (gdb) pp string
> 
>> (gdb) up
>> #11 0x00000001002514db in styled_format (nargs=2, args=0x7ffeefbf74c0,
>>    message=false) at editfns.c:3392
>> 3392			  width = lisp_string_width (arg, 0, nchars_string, prec,
>> (gdb) up
>> #12 0x000000010024f48f in Fformat (nargs=2, args=0x7ffeefbf74c0)
>>    at editfns.c:3061
>> 3061	  return styled_format (nargs, args, false);
> 
> What are the arguments to 'format' here?
> 
>  (gdb) pp args[0]
>  (gdb) pp args[1]
> 
>> (gdb) up
>> #13 0x000000010026b23b in call3 (fn=0x100420bf5, arg1=0x1000000000,
>>    arg2=0x7ffeefbf73f0, arg3=0x10026ec04 <xcdr_addr+20>) at eval.c:2912
>> 2912	{
> 
> What function is being called here, and with what arguments?
> 
>  (gdb) pp fn
>  (gdb) pp arg1
>  (gdb) pp arg2
>  (gdb) pp arg3
> 
> The command 'pp' is defined in src/.gdbinit, you may need to source
> that file before you could use the command.
> 
> Thanks.