Fix vertical cursor motion across overlay strings with newlines

* src/indent.c (Fvertical_motion): Don't leave point in the middle
of an overlay string with newlines, as that will position the
cursor after the string at whatever column is there.  (Bug#21468)

1 files changed, 24 insertions, 1 deletions

diff --git a/src/indent.c b/src/indent.c
index 7e8f0a573a3..777cd36cc52 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -2195,7 +2195,30 @@ whether or not it is currently displayed in some window.  */)
          was originally hscrolled, the goal column is interpreted as
          an addition to the hscroll amount.  */
       if (lcols_given)
-        move_it_in_display_line (&it, ZV, first_x + to_x, MOVE_TO_X);
+        {
+          move_it_in_display_line (&it, ZV, first_x + to_x, MOVE_TO_X);
+          /* If we find ourselves in the middle of an overlay string
+             which includes a newline after current string position,
+             we need to move by lines until we get out of the string,
+             and then reposition point at the requested X coordinate;
+             if we don't, the cursor will be placed just after the
+             string, which might not be the requested column.  */
+          if (nlines > 0
+              && it.method == GET_FROM_STRING
+              && !it.string_from_display_prop_p
+              && it.area == TEXT_AREA)
+            {
+              while (it.method == GET_FROM_STRING
+                     && !it.string_from_display_prop_p
+                     && memchr (SSDATA (it.string) + IT_STRING_BYTEPOS (it),
+                                '\n',
+                                SBYTES (it.string) - IT_STRING_BYTEPOS (it)))
+                {
+                  move_it_by_lines (&it, 1);
+                  move_it_in_display_line (&it, ZV, first_x + to_x, MOVE_TO_X);
+                }
+            }
+        }
 
       SET_PT_BOTH (IT_CHARPOS (it), IT_BYTEPOS (it));
       bidi_unshelve_cache (itdata, 0);