Try to fix bug#5314. This is probably not the final word, tho.

* buffer.c (Fset_buffer_modified_p): Try and be careful not to modify
recent-auto-save-p as a side-effect.
* buffer.h (BUF_AUTOSAVE_MODIFF): New macro.
* buffer.c (Fkill_buffer, reset_buffer):
* editfns.c (Fsubst_char_in_region):
* fileio.c (Finsert_file_contents, Fdo_auto_save)
(Fset_buffer_auto_saved, Frecent_auto_save_p): Use it.

5 files changed, 63 insertions, 26 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 6e3fc4ff1c5..1ad107b566c 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,17 +1,28 @@
+2010-01-13  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        Try to fix bug#5314.  This is probably not the final word, tho.
+        * buffer.c (Fset_buffer_modified_p): Try and be careful not to modify
+        recent-auto-save-p as a side-effect.
+        * buffer.h (BUF_AUTOSAVE_MODIFF): New macro.
+        * buffer.c (Fkill_buffer, reset_buffer):
+        * editfns.c (Fsubst_char_in_region):
+        * fileio.c (Finsert_file_contents, Fdo_auto_save)
+        (Fset_buffer_auto_saved, Frecent_auto_save_p): Use it.
+
 2010-01-13  Kenichi Handa  <handa@m17n.org>
 
         Display buffer name, etc. in mode line by composing correctly.
 
         * xdisp.c (reseat_to_string): Call composition_compute_stop_pos if
         STRING is not nil.
-        (display_mode_element): Adjusted for the change of
+        (display_mode_element): Adjust for the change of
         decode_mode_spec and display_line.
         (decode_mode_spec): Change arg MULTIBYTE to STRING.
         (display_string): Handle the case that STRING is non-null and
         LISP_STRING is not nil.
 
-        * xterm.c (x_draw_composite_glyph_string_foreground): Pay
-        attention to s->face->overstrike.
+        * xterm.c (x_draw_composite_glyph_string_foreground):
+        Pay attention to s->face->overstrike.
 
         * composite.c (composition_reseat_it): Don't check PT if STRING is
         non nil.
@@ -125,8 +136,8 @@
         (x_set_window_size): ... to here. bug #2568.
 
         * gtkutil.c (xg_clear_under_internal_border): New function.
-        (xg_frame_resized, xg_frame_set_char_size): Call
-        xg_clear_under_internal_border.
+        (xg_frame_resized, xg_frame_set_char_size):
+        Call xg_clear_under_internal_border.
         (xg_update_scrollbar_pos): Clear under old scroll bar position.
 
 2010-01-05  Chong Yidong  <cyd@stupidchicken.com>
@@ -250,8 +261,8 @@
         and atimer.h.
         (minibuf.o): Depend on systime.h and coding.h.  Don't depend on
         dispextern.h explicitly.
-        (print.o): Depend on termhooks.h, coding.h, and ccl.h.  Don't
-        depend explicitly on dispextern.h and composite.h.
+        (print.o): Depend on termhooks.h, coding.h, and ccl.h.
+        Don't depend explicitly on dispextern.h and composite.h.
         (process.o): Depend on character.h, xgselect.h, and sysselect.h.
         (regex.o): Don't depend on charset.h.
         (scroll.o): Depend on systime.h, coding.h, composite.h, and window.h.
@@ -430,8 +441,8 @@
 
 2009-12-04  Eli Zaretskii  <eliz@gnu.org>
 
-        * dispextern.h (enum prop_idx) <AUTO_COMPOSED_PROP_IDX>: Delete
-        unused enumeration value.
+        * dispextern.h (enum prop_idx) <AUTO_COMPOSED_PROP_IDX>:
+        Delete unused enumeration value.
 
 2009-12-03  Eli Zaretskii  <eliz@gnu.org>
 
@@ -562,8 +573,8 @@
 
 2009-11-21  Andreas Schwab  <schwab@linux-m68k.org>
 
-        * character.h (STRING_CHAR, STRING_CHAR_AND_LENGTH): Remove
-        ignored second argument.  All callers changed.
+        * character.h (STRING_CHAR, STRING_CHAR_AND_LENGTH):
+        Remove ignored second argument.  All callers changed.
         * regex.c (STRING_CHAR, STRING_CHAR_AND_LENGTH, RE_STRING_CHAR)
         (RE_STRING_CHAR_AND_LENGTH): Likewise.
         * xdisp.c (string_char_and_length): Likewise.
diff --git a/src/buffer.c b/src/buffer.c
index 8657fd8cdff..1880581c0a1 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -1,7 +1,7 @@
 /* Buffer manipulation primitives for GNU Emacs.
    Copyright (C) 1985, 1986, 1987, 1988, 1989, 1993, 1994,
                  1995, 1997, 1998, 1999, 2000, 2001, 2002,
-                 2003, 2004, 2005, 2006, 2007, 2008, 2009
+                 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
                  Free Software Foundation, Inc.
 
 This file is part of GNU Emacs.
@@ -704,7 +704,7 @@ reset_buffer (b)
   b->clip_changed = 0;
   b->prevent_redisplay_optimizations_p = 1;
   b->backed_up = Qnil;
-  b->auto_save_modified = 0;
+  BUF_AUTOSAVE_MODIFF (b) = 0;
   b->auto_save_failure_time = -1;
   b->auto_save_file_name = Qnil;
   b->read_only = Qnil;
@@ -1132,7 +1132,25 @@ A non-nil FLAG means mark the buffer modified.  */)
     }
 #endif /* CLASH_DETECTION */
 
-  SAVE_MODIFF = NILP (flag) ? MODIFF : 0;
+  /* Here we have a problem.  SAVE_MODIFF is used here to encode
+     buffer-modified-p (as SAVE_MODIFF<MODIFF) as well as
+     recent-auto-save-p (as SAVE_MODIFF<auto_save_modified).  So if we
+     modify SAVE_MODIFF to affect one, we may affect the other
+     as well.
+     E.g. if FLAG is nil we need to set SAVE_MODIFF to MODIFF, but
+     if SAVE_MODIFF<auto_save_modified that means we risk changing
+     recent-auto-save-p from t to nil.
+     Vice versa, if FLAG is non-nil and SAVE_MODIFF>=auto_save_modified
+     we risk changing recent-auto-save-p from nil to t.  */
+  SAVE_MODIFF = (NILP (flag)
+                 /* FIXME: This unavoidably sets recent-auto-save-p to nil.  */
+                 ? MODIFF
+                 /* Let's try to preserve recent-auto-save-p.  */
+                 : SAVE_MODIFF < MODIFF ? SAVE_MODIFF
+                 /* If SAVE_MODIFF == auto_save_modified == MODIFF,
+                    we can either decrease SAVE_MODIFF and auto_save_modified
+                    or increase MODIFF.  */
+                 : MODIFF++);
 
   /* Set update_mode_lines only if buffer is displayed in some window.
      Packages like jit-lock or lazy-lock preserve a buffer's modified
@@ -1541,8 +1559,8 @@ with SIGHUP.  */)
   /* Delete any auto-save file, if we saved it in this session.
      But not if the buffer is modified.  */
   if (STRINGP (b->auto_save_file_name)
-      && b->auto_save_modified != 0
-      && BUF_SAVE_MODIFF (b) < b->auto_save_modified
+      && BUF_AUTOSAVE_MODIFF (b) != 0
+      && BUF_SAVE_MODIFF (b) < BUF_AUTOSAVE_MODIFF (b)
       && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)
       && NILP (Fsymbol_value (intern ("auto-save-visited-file-name"))))
     {
diff --git a/src/buffer.h b/src/buffer.h
index 9f57a292053..5217c6d7298 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -1,6 +1,6 @@
 /* Header file for the buffer manipulation primitives.
    Copyright (C) 1985, 1986, 1993, 1994, 1995, 1997, 1998, 1999, 2000, 2001,
-                 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
+                 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
                  Free Software Foundation, Inc.
 
 This file is part of GNU Emacs.
@@ -158,6 +158,10 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 /* Overlay modification count.  */
 #define BUF_OVERLAY_MODIFF(buf) ((buf)->text->overlay_modiff)
 
+/* Modification count as of last auto-save.  */
+/* FIXME: should we move this into ->text->auto_save_modiff?  */
+#define BUF_AUTOSAVE_MODIFF(buf) ((buf)->auto_save_modified)
+
 /* Interval tree of buffer.  */
 #define BUF_INTERVALS(buf) ((buf)->text->intervals)
 
diff --git a/src/editfns.c b/src/editfns.c
index 58e13b1ed7c..00ac0ca0fa9 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -1,7 +1,7 @@
 /* Lisp functions pertaining to editing.
    Copyright (C) 1985, 1986, 1987, 1989, 1993, 1994, 1995, 1996,
                  1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
-                 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+                 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
 
 This file is part of GNU Emacs.
 
@@ -2870,8 +2870,8 @@ Both characters must have the same length of multi-byte form.  */)
                 {
                   if (MODIFF - 1 == SAVE_MODIFF)
                     SAVE_MODIFF++;
-                  if (MODIFF - 1 == current_buffer->auto_save_modified)
-                    current_buffer->auto_save_modified++;
+                  if (MODIFF - 1 == BUF_AUTOSAVE_MODIFF (current_buffer))
+                    BUF_AUTOSAVE_MODIFF (current_buffer)++;
                 }
 
               /* The before-change-function may have moved the gap
diff --git a/src/fileio.c b/src/fileio.c
index b815c38956e..d6cb814641b 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -1,7 +1,7 @@
 /* File IO for GNU Emacs.
    Copyright (C) 1985, 1986, 1987, 1988, 1993, 1994, 1995, 1996,
                  1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
-                 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+                 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
 
 This file is part of GNU Emacs.
 
@@ -4097,7 +4097,7 @@ variable `last-coding-system-used' to the coding system actually used.  */)
         }
 
       SAVE_MODIFF = MODIFF;
-      current_buffer->auto_save_modified = MODIFF;
+      BUF_AUTOSAVE_MODIFF (current_buffer) = MODIFF;
       XSETFASTINT (current_buffer->save_length, Z - BEG);
 #ifdef CLASH_DETECTION
       if (NILP (handler))
@@ -5307,7 +5307,7 @@ A non-nil CURRENT-ONLY argument means save only current buffer.  */)
            and file changed since last real save.  */
         if (STRINGP (b->auto_save_file_name)
             && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)
-            && b->auto_save_modified < BUF_MODIFF (b)
+            && BUF_AUTOSAVE_MODIFF (b) < BUF_MODIFF (b)
             /* -1 means we've turned off autosaving for a while--see below.  */
             && XINT (b->save_length) >= 0
             && (do_handled_files
@@ -5349,7 +5349,7 @@ A non-nil CURRENT-ONLY argument means save only current buffer.  */)
               message1 ("Auto-saving...");
             internal_condition_case (auto_save_1, Qt, auto_save_error);
             auto_saved++;
-            b->auto_save_modified = BUF_MODIFF (b);
+            BUF_AUTOSAVE_MODIFF (b) = BUF_MODIFF (b);
             XSETFASTINT (current_buffer->save_length, Z - BEG);
             set_buffer_internal (old);
 
@@ -5394,7 +5394,9 @@ DEFUN ("set-buffer-auto-saved", Fset_buffer_auto_saved,
 No auto-save file will be written until the buffer changes again.  */)
      ()
 {
-  current_buffer->auto_save_modified = MODIFF;
+  /* FIXME: This should not be called in indirect buffers, since
+     they're not autosaved.  */
+  BUF_AUTOSAVE_MODIFF (current_buffer) = MODIFF;
   XSETFASTINT (current_buffer->save_length, Z - BEG);
   current_buffer->auto_save_failure_time = -1;
   return Qnil;
@@ -5417,7 +5419,9 @@ in the visited file.  If the buffer has no visited file,
 then any auto-save counts as "recent".  */)
      ()
 {
-  return (SAVE_MODIFF < current_buffer->auto_save_modified) ? Qt : Qnil;
+  /* FIXME: maybe we should return nil for indirect buffers since
+     they're never autosaved.  */
+  return (SAVE_MODIFF < BUF_AUTOSAVE_MODIFF (current_buffer) ? Qt : Qnil);
 }
 
 /* Reading and completing file names */