(try_window_id): Don't use XFASTINT as an lvalue.

diff --git a/src/xdisp.c b/src/xdisp.c
index 28a3b868da0a62669e60bbd321801e4d042c8e56..7f3d05deec4419ca75643baf30870f38dd521a85 100644 (file)
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -1590,7 +1590,8 @@ try_window_id (window)
       if (i == xp.bufpos)
        return -2;
 
-      XFASTINT (w->window_end_vpos) += scroll_amount;
+      XSETFASTINT (w->window_end_vpos,
+                  XFASTINT (w->window_end_vpos) + scroll_amount);
 
       /* Before doing any scrolling, verify that point will be on frame. */
       if (PT > ep.bufpos && !(PT <= xp.bufpos && xp.bufpos < height))
@@ -1796,7 +1797,8 @@ try_window_id (window)
          val = *vmotion (Z - XFASTINT (w->window_end_pos),
                          delta, width, hscroll, window);
          XSETFASTINT (w->window_end_pos, Z - val.bufpos);
-         XFASTINT (w->window_end_vpos) += val.vpos;
+         XSETFASTINT (w->window_end_vpos,
+                      XFASTINT (w->window_end_vpos) + val.vpos);
        }
     }