[Emacs-diffs] Changes to emacs/src/xdisp.c,v

[Chong Yidong]

CVSROOT:        /sources/emacs
Module name:    emacs
Changes by:     Chong Yidong <cyd>      07/04/15 21:50:27

Index: xdisp.c
===================================================================
RCS file: /sources/emacs/emacs/src/xdisp.c,v
retrieving revision 1.1146
retrieving revision 1.1147
diff -u -b -r1.1146 -r1.1147
--- xdisp.c     10 Apr 2007 15:57:25 -0000      1.1146
+++ xdisp.c     15 Apr 2007 21:50:27 -0000      1.1147
@@ -12777,6 +12777,8 @@
   int rc;
   int centering_position = -1;
   int last_line_misfit = 0;
+  int save_beg_unchanged = BEG_UNCHANGED;
+  int save_end_unchanged = END_UNCHANGED;
 
   SET_TEXT_POS (lpoint, PT, PT_BYTE);
   opoint = lpoint;
@@ -13145,11 +13147,20 @@
          && NILP (do_mouse_tracking)
          && CHARPOS (startp) > BEGV)
        {
-         /* Make sure beg_unchanged and end_unchanged are up to date.
-            Do it only if buffer has really changed.  This may or may
-            not have been done by try_window_id (see which) already. */
+#if 0
+         /* The following code tried to make BEG_UNCHANGED and
+            END_UNCHANGED up to date (similar to try_window_id).
+            Is it important to do so?
+
+            The trouble is that it's a little too strict when it
+            comes to overlays: modify_overlay can call
+            BUF_COMPUTE_UNCHANGED, which alters BUF_BEG_UNCHANGED and
+            BUF_END_UNCHANGED directly without moving the gap.
+
+            This can result in spurious recentering when overlays are
+            altered in the buffer.  So unless it's proven necessary,
+            let's leave this commented out for now. -- cyd.  */
          if (MODIFF > SAVE_MODIFF
-             /* This seems to happen sometimes after saving a buffer.  */
              || BEG_UNCHANGED + END_UNCHANGED > Z_BYTE)
            {
              if (GPT - BEG < BEG_UNCHANGED)
@@ -13157,9 +13168,10 @@
              if (Z - GPT < END_UNCHANGED)
                END_UNCHANGED = Z - GPT;
            }
+#endif
 
-         if (CHARPOS (startp) > BEG + BEG_UNCHANGED
-             && CHARPOS (startp) <= Z - END_UNCHANGED)
+         if (CHARPOS (startp) > BEG + save_beg_unchanged
+             && CHARPOS (startp) <= Z - save_end_unchanged)
            {
              /* There doesn't seems to be a simple way to find a new
                 window start that is near the old window start, so