Prevent infloops in redisplay due to truncate-lines and overlays

* src/xdisp.c (hscroll_window_tree): Avoid inflooping in
redisplay_window when a screen line ends in an overlay string with
a newline.  (Bug#25246)

1 files changed, 11 insertions, 0 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index ad0b9686f04..5de5ecaef0d 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -13049,6 +13049,17 @@ hscroll_window_tree (Lisp_Object window)
 	      init_to_row_start (&it, w, cursor_row);
 	      it.last_visible_x = INFINITY;
 	      move_it_in_display_line_to (&it, pt, -1, MOVE_TO_POS);
+	      /* If the line ends in an overlay string with a newline,
+		 we might infloop, because displaying the window will
+		 want to put the cursor after the overlay, i.e. at X
+		 coordinate of zero on the next screen line.  So we
+		 use the buffer position prior to the overlay string
+		 instead.  */
+	      if (it.method == GET_FROM_STRING && pt > 1)
+		{
+		  init_to_row_start (&it, w, cursor_row);
+		  move_it_in_display_line_to (&it, pt - 1, -1, MOVE_TO_POS);
+		}
 	      current_buffer = saved_current_buffer;
 
 	      /* Position cursor in window.  */