bug#26980: 25.2; Freeze & redisplay_internal & macOS

[Eli Zaretskii]

> From: Robert Vojta <rvojta@me.com>
> Date: Fri, 26 May 2017 13:01:52 +0200
> Cc: alan@idiocy.org, 26980@debbugs.gnu.org
> 
> > * thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 4.1
> >    frame #0: 0x0000000100092643 Emacs`redisplay_window(window=4836536885, 
> > just_this_one_p=false) at xdisp.c:17288
> >   17285           if (WINDOW_WANTS_MODELINE_P (w)
> >   17286               && CURRENT_MODE_LINE_HEIGHT (w) != 
> > DESIRED_MODE_LINE_HEIGHT (w))
> >   17287             {
> > -> 17288              f->fonts_changed = true;
> >   17289               w->mode_line_height = -1;
> >   17290               MATRIX_MODE_LINE_ROW (w->current_matrix)->height
> >   17291                 = DESIRED_MODE_LINE_HEIGHT (w);
> > (lldb)
> 
> 9: file = 'xdisp.c', line = 17288, exact_match = 0, locations = 1, resolved = 
> 1, hit count = 225
>     Breakpoint commands:
>       p w->mode_line_height
>       p (w->desired_matrix->rows + w->desired_matrix->nrows - 1)->height
>       process continue
> 
> Never ending loop where CURRENT_MODE_LINE_HEIGHT(w) returns 21 and 
> DESIRED_MODE_LINE_HEIGHT(w) returns 20.
> 
> (lldb)  p w->mode_line_height
> (int) $587 = 21
> (lldb)  p (w->desired_matrix->rows + w->desired_matrix->nrows - 1)->height
> (int) $588 = 20

Can you see where w->mode_line_height is computed, and try to
understand why it comes out as 21 instead of 20?

Also, what is supposed to be displayed on the mode line in this
window?  Something special you have there?

Thanks.