Continue working on handling of properties in bidi iteration.

Region display and extension seems to work.
Solved a crash in bidirectional display of etc/HELLO.
(HELLO display still not 100% OK, e.g. near Kannada.)

 .gdbinit (pitx): Display some bidi information about the
 iterator.

 dispextern.h (BIDI_AT_BASE_LEVEL): Enclose definition in
 parentheses.

 xdisp.c (handle_stop_backwards): Save and restore it->current
 and it->position, instead of expecting the caller to do that.
 (next_element_from_buffer): When moving across stop_charpos,
 record it in prev_stop.  When IT_CHARPOS backs up, call
 handle_stop_backwards only if above the base embedding level.
 This solves the crash while displaying etc/HELLO in bidi mode.

1 files changed, 4 insertions, 3 deletions

diff --git a/src/dispextern.h b/src/dispextern.h
index 510ffe50dab..0521a062351 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -1812,7 +1812,7 @@ struct bidi_it {
 /* Value is non-zero when the bidi iterator is at base paragraph
    embedding level.  */
 #define BIDI_AT_BASE_LEVEL(BIDI_IT) \
-  (BIDI_IT).resolved_level == (BIDI_IT).level_stack[0].level
+  ((BIDI_IT).resolved_level == (BIDI_IT).level_stack[0].level)
 
 
 /***********************************************************************
@@ -2013,10 +2013,11 @@ struct it
   EMACS_INT stop_charpos;
 
   /* Previous stop position, i.e. the last one before the current
-     buffer position.  */
+     iterator position in `current'.  */
   EMACS_INT prev_stop;
 
-  /* Last stop_pos at the current paragraph's embedding level.  */
+  /* Last stop position iterated across whose embedding level is equal
+     to the current paragraph's embedding level.  */
   EMACS_INT base_level_stop;
 
   /* Maximum string or buffer position + 1.  ZV when iterating over