Avoid crashes due to bidi cache being reset during redisplay

If automatic character composition triggers GC, and
'garbage-collection-messages' are turned on, we could have the
bidi cache reset while processing RTL text, which would then
consistently crash.
* src/xdisp.c (display_echo_area_1): Protect the bidi cache
against changes inside 'try_window'.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index bff6218106b..60848f4433e 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -11539,7 +11539,9 @@ display_echo_area_1 (ptrdiff_t a1, Lisp_Object a2)
   /* Display.  */
   clear_glyph_matrix (w->desired_matrix);
   XSETWINDOW (window, w);
+  void *itdata = bidi_shelve_cache ();
   try_window (window, start, 0);
+  bidi_unshelve_cache (itdata, false);
 
   return window_height_changed_p;
 }