Fix infloop in redisplay due to truncated lines and invisible text

* src/xdisp.c (forward_to_next_line_start): Don't call
'get_next_display_element' after finding the end of line.  This
avoids setting the row's end position to the wrong value when the
next screen line begins with invisible text; that wrong value
caused set_cursor_from_row position the cursor in the wrong screen
line, and eventually triggered bug#24109.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index 42c6fb75efa..a13830c811e 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -6298,9 +6298,10 @@ forward_to_next_line_start (struct it *it, bool *skipped_p,
         }
       else
         {
-          while (get_next_display_element (it)
-                 && !newline_found_p)
+          while (!newline_found_p)
             {
+              if (!get_next_display_element (it))
+                break;
               newline_found_p = ITERATOR_AT_END_OF_LINE_P (it);
               if (newline_found_p && it->bidi_p && bidi_it_prev)
                 *bidi_it_prev = it->bidi_it;