From: Eli Zaretskii <eliz@gnu.org>
Date: Tue, 13 Mar 2018 16:00:23 +0000 (+0200)
Subject: Avoid assertion violation under visual-order-cursor-movement
X-Git-Tag: emacs-26.1-rc1~95
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=3e39897cd03a10b5d1ac75a89f999943e3dad5c0;p=emacs.git

Avoid assertion violation under visual-order-cursor-movement

* src/xdisp.c (Fmove_point_visually): Don't let point exceed the
BEGV..ZV range.  Signal Beginning of buffer error when there's a
before-string at BEGV.  (Bug#30787)
---

diff --git a/src/xdisp.c b/src/xdisp.c
index b003a2f9ccc..fb6729c36aa 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -22430,6 +22430,11 @@ Value is the new character position of point.  */)
 		    new_pos += (row->reversed_p ? -dir : dir);
 		  else
 		    new_pos -= (row->reversed_p ? -dir : dir);
+		  new_pos = clip_to_bounds (BEGV, new_pos, ZV);
+		  /* If we didn't move, we've hit BEGV or ZV, so we
+		     need to signal a suitable error.  */
+		  if (new_pos == PT)
+		    break;
 		}
 	      else if (BUFFERP (g->object))
 		new_pos = g->charpos;