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));