Avoid aborts/assertion violations due to 'vim-empty-lines-mode'

* src/xdisp.c (handle_single_display_spec): If position to be
restored after processing the display property comes from an
overlay, protect against that overlay's end point being outside of
the narrowed region.
Reported by Filipe Silva <filipe.silva@gmail.com> in
http://lists.gnu.org/archive/html/emacs-devel/2017-03/msg00176.html.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index 1e7cb4ec665..7ff37a6fb48 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -4999,6 +4999,14 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
         {
           ptrdiff_t ovendpos = OVERLAY_POSITION (OVERLAY_END (overlay));
 
+          /* Some borderly-sane Lisp might call us with the current
+             buffer narrowed so that overlay-end is outside the
+             POINT_MIN..POINT_MAX region, which will then cause
+             various assertion violations and crashes down the road,
+             starting with pop_it when it will attempt to use POSITION
+             set below.  Prevent that.  */
+          ovendpos = clip_to_bounds (BEGV, ovendpos, ZV);
+
           if (ovendpos > CHARPOS (*position))
             SET_TEXT_POS (*position, ovendpos, CHAR_TO_BYTE (ovendpos));
         }