Fix bug #17823 with vertical-motion in lines with line-prefix.

 src/indent.c (Fvertical_motion): Move to the goal column, if any,
 with a single call to move_it_in_display_line, not in two calls.
 Doing this with two calls causes move_it_in_display_line apply the
 line-prefix handling twice instead of just once.

2 files changed, 10 insertions, 12 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 93a25ba2871..cd82e91c2dd 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,6 +1,10 @@
 2014-06-21  Eli Zaretskii  <eliz@gnu.org>
 
 	* indent.c (Fvertical_motion): Doc fix.
+	Move to the goal column, if any, with a single call to
+	move_it_in_display_line, not in two calls.  Doing this with two
+	calls causes move_it_in_display_line apply the line-prefix
+	handling twice instead of just once.  (Bug#17823)
 
 2014-06-21  Paul Eggert  <eggert@cs.ucla.edu>
 
diff --git a/src/indent.c b/src/indent.c
index f492461bf50..711792f75cd 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -2129,20 +2129,14 @@ whether or not it is currently displayed in some window.  */)
 	    }
 	}
 
-      /* Move to the goal column, if one was specified.  */
+      /* Move to the goal column, if one was specified.  If the window
+	 was originally hscrolled, the goal column is interpreted as
+	 an addition to the hscroll amount.  */
       if (!NILP (lcols))
 	{
-	  /* If the window was originally hscrolled, move forward by
-	     the hscrolled amount first.  */
-	  if (first_x > 0)
-	    {
-	      move_it_in_display_line (&it, ZV, first_x, MOVE_TO_X);
-	      it.current_x = 0;
-	    }
-	  move_it_in_display_line
-	    (&it, ZV,
-	     (int)(cols * FRAME_COLUMN_WIDTH (XFRAME (w->frame)) + 0.5),
-	     MOVE_TO_X);
+	  int to_x = (int)(cols * FRAME_COLUMN_WIDTH (XFRAME (w->frame)) + 0.5);
+
+	  move_it_in_display_line (&it, ZV, first_x + to_x, MOVE_TO_X);
 	}
 
       SET_PT_BOTH (IT_CHARPOS (it), IT_BYTEPOS (it));