Fix bugs #13623 and 13626 caused by changes in 2013-02-01T07:23:18Z!dmantipov@yandex.ru.

 src/xdisp.c (window_buffer_changed): region_showing can be negative,
 which still means region is being displayed.
 (redisplay_internal): Resurrect code that forced redisplay of the
 whole window when showing region and the mark has changed.  Record
 the new mark position to allow redisplay optimizations.
 (display_line): If it->region_beg_charpos is non-zero, set the
 window's region_showing member to -1.
 src/window.h (struct window) <region_showing>: Declare ptrdiff_t,
 not bitfield of 1 bit.

3 files changed, 33 insertions, 5 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 1c7771cb0d9..6f52f764a97 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,16 @@
+2013-02-04  Eli Zaretskii  <eliz@gnu.org>
+
+        * xdisp.c (window_buffer_changed): region_showing can be negative,
+        which still means region is being displayed.
+        (redisplay_internal): Resurrect code that forced redisplay of the
+        whole window when showing region and the mark has changed.  Record
+        the new mark position to allow redisplay optimizations.
+        (display_line): If it->region_beg_charpos is non-zero, set the
+        window's region_showing member to -1.  (Bug#13623)  (Bug#13626)
+
+        * window.h (struct window) <region_showing>: Declare ptrdiff_t,
+        not bitfield of 1 bit.
+
 2013-02-03  Daniel Colascione  <dancol@dancol.org>
 
         * emacs.c: Use execvp, not execv, when DAEMON_MUST_EXEC, so that
diff --git a/src/window.h b/src/window.h
index f28ce1424d0..0f4f242641e 100644
--- a/src/window.h
+++ b/src/window.h
@@ -333,13 +333,15 @@ struct window
        the frame image that window_end_pos did not get onto the frame.  */
     unsigned window_end_valid : 1;
 
-    /* Nonzero if we have highlighted the region (or any part of it).  */
-    unsigned region_showing : 1;
-
     /* Amount by which lines of this window are scrolled in
        y-direction (smooth scrolling).  */
     int vscroll;
 
+    /* If we have highlighted the region (or any part of it), the mark
+       position or -1 (the latter is used by the iterator for internal
+       purposes); otherwise zero.  */
+    ptrdiff_t region_showing;
+
     /* Z_BYTE - buffer position of the last glyph in the current matrix of W.
        Should be nonnegative, and only valid if window_end_valid is nonzero.  */
     ptrdiff_t window_end_bytepos;
diff --git a/src/xdisp.c b/src/xdisp.c
index 7b6e108d97f..a958fd51e39 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -10753,7 +10753,7 @@ window_buffer_changed (struct window *w)
 
   return (((BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)) != w->last_had_star)
           || ((!NILP (Vtransient_mark_mode) && !NILP (BVAR (b, mark_active)))
-              != w->region_showing));
+              != (w->region_showing != 0)));
 }
 
 /* Nonzero if W has %c in its mode line and mode line should be updated.  */
@@ -13016,6 +13016,17 @@ redisplay_internal (void)
       clear_garbaged_frames ();
     }
 
+  /* If showing the region, and mark has changed, we must redisplay
+     the whole window.  The assignment to this_line_start_pos prevents
+     the optimization directly below this if-statement.  */
+  if (((!NILP (Vtransient_mark_mode)
+        && !NILP (BVAR (XBUFFER (w->buffer), mark_active)))
+       != (w->region_showing > 0))
+      || (w->region_showing
+          && w->region_showing
+          != XINT (Fmarker_position (BVAR (XBUFFER (w->buffer), mark)))))
+    CHARPOS (this_line_start_pos) = 0;
+
   /* Optimize the case that only the line containing the cursor in the
      selected window has changed.  Variables starting with this_ are
      set in display_line and record information about the line
@@ -13228,6 +13239,8 @@ redisplay_internal (void)
   ++clear_image_cache_count;
 #endif
 
+  w->region_showing = XINT (Fmarker_position (BVAR (XBUFFER (w->buffer), mark)));
+
   /* Build desired matrices, and update the display.  If
      consider_all_windows_p is non-zero, do it for all windows on all
      frames.  Otherwise do it for selected_window, only.  */
@@ -19120,7 +19133,7 @@ display_line (struct it *it)
     }
 
   /* Is IT->w showing the region?  */
-  it->w->region_showing = it->region_beg_charpos > 0;
+  it->w->region_showing = it->region_beg_charpos > 0 ? -1 : 0;
 
   /* Clear the result glyph row and enable it.  */
   prepare_desired_row (row);