bug#27668: 26.0.50; Crash with display-line-numbers t

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Date: Thu, 13 Jul 2017 18:42:49 +0200
> 
> (gdb) break xdisp.c:21010 if it->glyph_row != 0 && it->glyph_row->used[1] > 0
> Breakpoint 4 at 0x45baaf: file xdisp.c, line 21010.
> (gdb) run
> Starting program: /home/rpluim/repos/emacs-master/src/emacs 
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
> [New Thread 0x7fffe4de5700 (LWP 19567)]
> [New Thread 0x7fffdffff700 (LWP 19568)]
> [New Thread 0x7fffdf5f1700 (LWP 19569)]
> 
> Thread 1 "emacs" hit Breakpoint 4, maybe_produce_line_number 
> (it=it@entry=0x7fffffff8130) at xdisp.c:21010
> 21010   short *u = it->glyph_row ? &it->glyph_row->used[TEXT_AREA] : NULL;
> 
> 
> I was in the process of switching from a non-line-number to a
> line-number buffer when that hit.

OK, thanks.  What is the value of it->glyph_row->used[TEXT_AREA], and
what is the backtrace?