Avoid errors in vertical-motion when buffer is narrowed

* src/indent.c (Fvertical_motion): If need to start from
window-start, and it is outside of the accessible portion,
temporarily widen the buffer.  This avoids errors in evil-mode.
Reported by James Nguyen <james@jojojames.com>.

1 files changed, 13 insertions, 0 deletions

diff --git a/src/indent.c b/src/indent.c
index 2cacfbbe3c0..70351f90466 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -2077,11 +2077,24 @@ whether or not it is currently displayed in some window.  */)
           && !EQ (Vdisplay_line_numbers, Qvisual))
         {
           struct text_pos wstart;
+          bool saved_restriction = false;
+          ptrdiff_t count1 = SPECPDL_INDEX ();
           SET_TEXT_POS_FROM_MARKER (wstart, w->start);
           itdata = bidi_shelve_cache ();
+          /* We must start from window's start point, but it could be
+             outside the accessible region.  */
+          if (wstart.charpos < BEGV || wstart.charpos > ZV)
+            {
+              record_unwind_protect (save_restriction_restore,
+                                     save_restriction_save ());
+              Fwiden ();
+              saved_restriction = true;
+            }
           start_display (&it, w, wstart);
           move_it_by_lines (&it, 1);
           lnum_width = it.lnum_width;
+          if (saved_restriction)
+            unbind_to (count1, Qnil);
           bidi_unshelve_cache (itdata, 0);
         }
       SET_TEXT_POS (pt, PT, PT_BYTE);