bug#52947: 29.0.50; Newline in tab-bar-format causes lockup

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: dlacewell@gmail.com,  52947@debbugs.gnu.org
> Date: Sun, 02 Jan 2022 20:38:31 +0200
> 
> > Do we want to support newlines there? what would be the purpose of
> > having newlines in the tabs?
> 
> I don't know, menus can't have newlines too.
> 
> > Also, you say "display engine", so does it mean you've found where we
> > infloop with these recipes?  If so, can you tell the details?
> 
> It gives such backtrace:
> 
> (gdb) bt
> #0  make_lisp_symbol (sym=0x555555cfd9c0 <lispsym>) at lisp.h:1002
> #1  0x00005555555b9766 in builtin_lisp_symbol (index=0) at lisp.h:1008
> #2  0x00005555555b9cf6 in CHAR_TABLE_REF_ASCII (ct=XIL(0x7ffff0b438dd), 
> idx=10) at lisp.h:2031
> #3  0x00005555555b9d3e in CHAR_TABLE_REF (ct=XIL(0x7ffff0b438dd), idx=10) at 
> lisp.h:2042
> #4  0x00005555555d16de in lookup_glyphless_char_display (c=10, 
> it=0x7fffffff75d0) at xdisp.c:7410
> #5  0x00005555555d1f8c in get_next_display_element (it=0x7fffffff75d0) at 
> xdisp.c:7599
> #6  0x00005555555e3133 in display_tab_bar_line (it=0x7fffffff75d0, height=-1) 
> at xdisp.c:13389
> #7  0x00005555555e3901 in tab_bar_height (f=0x5555560a2dc8, 
> n_rows=0x5555560a2f08, pixelwise=true) at xdisp.c:13515
> #8  0x00005555555e3c27 in redisplay_tab_bar (f=0x5555560a2dc8) at 
> xdisp.c:13597

Thanks, should be fixed now on the emacs-28 branch.