master 69b186c1bc0: Fix move_it_* functions when moving across face with :box

branch: master
commit 69b186c1bc02785977a51854f19f940f1bce140d
Author: Eli Zaretskii <[email protected]>
Commit: Eli Zaretskii <[email protected]>

    Fix move_it_* functions when moving across face with :box
    
    * src/xdisp.c (move_it_in_display_line_to): Restore the
    it->start_of_box_run_p flag upon exiting, to the value it had
    before calling PRODUCE_GLYPHS for the last time, if the iterator
    didn't move to the next display element.  This prevents losing the
    flag in further calls to move_it_* functions.  (Bug#81570)
---
 src/xdisp.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/xdisp.c b/src/xdisp.c
index f01ed8cb053..beb8d980ee3 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -10122,6 +10122,8 @@ move_it_in_display_line_to (struct it *it,
   bool saw_smaller_pos = prev_pos < to_charpos;
   bool line_number_pending = false;
   int this_line_subject_to_line_prefix = 0;
+  bool moved_to_next = false;
+  bool saved_start_of_box_run = it->start_of_box_run_p;
 
 #ifdef GLYPH_DEBUG
   /* atx_flag, atpos_flag and wrap_flag are assigned but never used;
@@ -10203,6 +10205,8 @@ move_it_in_display_line_to (struct it *it,
   if (IT_CHARPOS (*it) < CHARPOS (this_line_min_pos))
     SET_TEXT_POS (this_line_min_pos, IT_CHARPOS (*it), IT_BYTEPOS (*it));
 
+  saved_start_of_box_run = it->start_of_box_run_p;
+
   while (true)
     {
       int x, i, ascent = 0, descent = 0;
@@ -10331,7 +10335,11 @@ move_it_in_display_line_to (struct it *it,
 	 line.  */
       x = it->current_x;
 
+      /* We will record the start_of_box_run_p flag to restore it before
+         exiting if we never move from this glyph.  */
+      saved_start_of_box_run = it->start_of_box_run_p;
       PRODUCE_GLYPHS (it);
+      moved_to_next = false;
 
       if (it->area != TEXT_AREA)
 	{
@@ -10339,6 +10347,7 @@ move_it_in_display_line_to (struct it *it,
 	  if (it->method == GET_FROM_BUFFER)
 	    prev_pos = IT_CHARPOS (*it);
 	  set_iterator_to_next (it, true);
+	  moved_to_next = true;
 	  if (IT_CHARPOS (*it) < CHARPOS (this_line_min_pos))
 	    SET_TEXT_POS (this_line_min_pos,
 			  IT_CHARPOS (*it), IT_BYTEPOS (*it));
@@ -10517,6 +10526,7 @@ move_it_in_display_line_to (struct it *it,
 			  if (it->method == GET_FROM_BUFFER)
 			    prev_pos = IT_CHARPOS (*it);
 			  set_iterator_to_next (it, true);
+			  moved_to_next = true;
 			  if (IT_CHARPOS (*it) < CHARPOS (this_line_min_pos))
 			    SET_TEXT_POS (this_line_min_pos,
 					  IT_CHARPOS (*it), IT_BYTEPOS (*it));
@@ -10722,6 +10732,7 @@ move_it_in_display_line_to (struct it *it,
       /* The current display element has been consumed.  Advance to
 	 the next.  */
       set_iterator_to_next (it, true);
+      moved_to_next = true;
 
       /* If IT has just finished producing glyphs for the wrap prefix
 	 and is proceeding to the next method, there might not be
@@ -10852,6 +10863,13 @@ move_it_in_display_line_to (struct it *it,
   if (ppos_data)
     bidi_unshelve_cache (ppos_data, true);
 
+  /* Restore the start_of_box_run_p flag, if we haven't moved from the
+     position where it might have been set by get_next_display_element.
+     This is so the following iteration picks up this flag instead of
+     losing it (because PRODUCE_GLYPHS resets it).   */
+  if (!moved_to_next)
+    it->start_of_box_run_p = saved_start_of_box_run;
+
   /* Restore the iterator settings altered at the beginning of this
      function.  */
   it->glyph_row = saved_glyph_row;