upstream

10 files changed, 135 insertions, 181 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 2a0c0e6822d..332656fcf00 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,45 @@
+2012-11-20  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        Conflate Qnil and Qunbound for `symbol-function'.
+        * alloc.c (Fmake_symbol): Initialize `function' to Qnil.
+        * lread.c (init_obarray): Set `function' fields to Qnil.
+        * eval.c (Fcommandp): Ignore Qunbound.
+        (Fautoload, eval_sub, Fapply, Ffuncall, Fmacroexpand):
+        * data.c (Ffset, Ffboundp, indirect_function, Findirect_function):
+        Test NILP rather than Qunbound.
+        (Ffmakunbound): Set to Qnil.
+        (Fsymbol_function): Never signal an error.
+        (Finteractive_form): Ignore Qunbound.
+
+2012-11-20  Paul Eggert  <eggert@cs.ucla.edu>
+
+        * eval.c (interactive_p): Remove no-longer-used decl.
+
+2012-11-20  Dmitry Antipov  <dmantipov@yandex.ru>
+
+        * xdisp.c (buffer_shared): Adjust comment.
+        (buffer_shared_and_changed): New function.
+        (prepare_menu_bars, redisplay_internal): Use it to
+        decide whether all windows or frames should be updated.
+        (window_outdated): New function.
+        (text_outside_line_unchanged_p, redisplay_window): Use it.
+        (redisplay_internal): Likewise.  Fix indentation.
+
+2012-11-20  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * eval.c (Finteractive_p, Fcalled_interactively_p, interactive_p): Remove.
+        (syms_of_eval): Remove corresponding defsubr.
+        * bytecode.c (exec_byte_code): `interactive-p' is now a Lisp function.
+
+2012-11-19  Daniel Colascione  <dancol@dancol.org>
+
+        * w32fns.c (Fx_file_dialog):
+        (Fx_file_dialog): Accomodate rename of cygwin_convert_path* to
+        cygwin_convert_file_name*.
+
+        * cygw32.c (Fcygwin_convert_path_to_windows, syms_of_cygw32):
+        Rename cygwin_convert_path* to cygwin_convert_file_name*.
+
 2012-11-18  Paul Eggert  <eggert@cs.ucla.edu>
 
         * nsterm.m (ns_select): Send SIGIO only to self, not to process group.
@@ -8,10 +50,10 @@
         windows.h gets included before w32term.h uses some of its
         features, see below.
 
-        * w32term.h (LOCALE_ENUMPROCA, LOCALE_ENUMPROCW) [_MSC_VER]: New
-        typedefs.
-        (EnumSystemLocalesA, EnumSystemLocalesW) [_MSC_VER]: New
-        prototypes.
+        * w32term.h (LOCALE_ENUMPROCA, LOCALE_ENUMPROCW) [_MSC_VER]:
+        New typedefs.
+        (EnumSystemLocalesA, EnumSystemLocalesW) [_MSC_VER]:
+        New prototypes.
         (EnumSystemLocales) [_MSC_VER]: Define if undefined.  (Bug#12878)
 
 2012-11-18  Jan Djärv  <jan.h.d@swipnet.se>
@@ -303,8 +345,8 @@
         * xdisp.c (try_scrolling): Fix correction of aggressive-scroll
         amount when the scroll margins are too large.  When scrolling
         backwards in the buffer, give up if cannot reach point or the
-        scroll margin within a reasonable number of screen lines.  Fixes
-        point position in window under scroll-up/down-aggressively when
+        scroll margin within a reasonable number of screen lines.
+        Fixes point position in window under scroll-up/down-aggressively when
         point is positioned many lines beyond the window top/bottom.
         (Bug#12811)
 
diff --git a/src/alloc.c b/src/alloc.c
index a66a752f5dc..22e3db3cc77 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -3212,7 +3212,7 @@ static struct Lisp_Symbol *symbol_free_list;
 
 DEFUN ("make-symbol", Fmake_symbol, Smake_symbol, 1, 1, 0,
        doc: /* Return a newly allocated uninterned symbol whose name is NAME.
-Its value and function definition are void, and its property list is nil.  */)
+Its value is void, and its function definition and property list are nil.  */)
   (Lisp_Object name)
 {
   register Lisp_Object val;
@@ -3249,7 +3249,7 @@ Its value and function definition are void, and its property list is nil.  */)
   set_symbol_plist (val, Qnil);
   p->redirect = SYMBOL_PLAINVAL;
   SET_SYMBOL_VAL (p, Qunbound);
-  set_symbol_function (val, Qunbound);
+  set_symbol_function (val, Qnil);
   set_symbol_next (val, NULL);
   p->gcmarkbit = 0;
   p->interned = SYMBOL_UNINTERNED;
diff --git a/src/bytecode.c b/src/bytecode.c
index 648813aed86..3267c7c8c76 100644
--- a/src/bytecode.c
+++ b/src/bytecode.c
@@ -1579,7 +1579,9 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
           NEXT;
 
         CASE (Binteractive_p):  /* Obsolete since 24.1.  */
-          PUSH (Finteractive_p ());
+          BEFORE_POTENTIAL_GC ();
+          PUSH (call0 (intern ("interactive-p")));
+          AFTER_POTENTIAL_GC ();
           NEXT;
 
         CASE (Bforward_char):
diff --git a/src/cygw32.c b/src/cygw32.c
index 54f2076a891..d9777d5e22e 100644
--- a/src/cygw32.c
+++ b/src/cygw32.c
@@ -106,22 +106,24 @@ conv_filename_from_w32_unicode (const wchar_t* in, int absolute_p)
   return unbind_to (count, DECODE_FILE (converted));
 }
 
-DEFUN ("cygwin-convert-path-to-windows",
-       Fcygwin_convert_path_to_windows, Scygwin_convert_path_to_windows,
+DEFUN ("cygwin-convert-file-name-to-windows",
+       Fcygwin_convert_file_name_to_windows,
+       Scygwin_convert_file_name_to_windows,
        1, 2, 0,
-       doc: /* Convert PATH to a Windows path.  If ABSOLUTE-P if
-               non-nil, return an absolute path.*/)
+       doc: /* Convert PATH to a Windows path.  If ABSOLUTE-P is
+non-nil, return an absolute path.*/)
   (Lisp_Object path, Lisp_Object absolute_p)
 {
   return from_unicode (
     conv_filename_to_w32_unicode (path, EQ (absolute_p, Qnil) ? 0 : 1));
 }
 
-DEFUN ("cygwin-convert-path-from-windows",
-       Fcygwin_convert_path_from_windows, Scygwin_convert_path_from_windows,
+DEFUN ("cygwin-convert-file-name-from-windows",
+       Fcygwin_convert_file_name_from_windows,
+       Scygwin_convert_file_name_from_windows,
        1, 2, 0,
        doc: /* Convert a Windows path to a Cygwin path.  If ABSOLUTE-P
-               if non-nil, return an absolute path.*/)
+is non-nil, return an absolute path.*/)
   (Lisp_Object path, Lisp_Object absolute_p)
 {
   return conv_filename_from_w32_unicode (to_unicode (path, &path),
@@ -131,6 +133,6 @@ DEFUN ("cygwin-convert-path-from-windows",
 void
 syms_of_cygw32 (void)
 {
-  defsubr (&Scygwin_convert_path_from_windows);
-  defsubr (&Scygwin_convert_path_to_windows);
+  defsubr (&Scygwin_convert_file_name_from_windows);
+  defsubr (&Scygwin_convert_file_name_to_windows);
 }
diff --git a/src/data.c b/src/data.c
index 09899400b68..5fc6afaaa03 100644
--- a/src/data.c
+++ b/src/data.c
@@ -543,12 +543,13 @@ DEFUN ("boundp", Fboundp, Sboundp, 1, 1, 0,
   return (EQ (valcontents, Qunbound) ? Qnil : Qt);
 }
 
+/* FIXME: Make it an alias for function-symbol!  */
 DEFUN ("fboundp", Ffboundp, Sfboundp, 1, 1, 0,
        doc: /* Return t if SYMBOL's function definition is not void.  */)
   (register Lisp_Object symbol)
 {
   CHECK_SYMBOL (symbol);
-  return EQ (XSYMBOL (symbol)->function, Qunbound) ? Qnil : Qt;
+  return NILP (XSYMBOL (symbol)->function) ? Qnil : Qt;
 }
 
 DEFUN ("makunbound", Fmakunbound, Smakunbound, 1, 1, 0,
@@ -564,14 +565,14 @@ Return SYMBOL.  */)
 }
 
 DEFUN ("fmakunbound", Ffmakunbound, Sfmakunbound, 1, 1, 0,
-       doc: /* Make SYMBOL's function definition be void.
+       doc: /* Make SYMBOL's function definition be nil.
 Return SYMBOL.  */)
   (register Lisp_Object symbol)
 {
   CHECK_SYMBOL (symbol);
   if (NILP (symbol) || EQ (symbol, Qt))
     xsignal1 (Qsetting_constant, symbol);
-  set_symbol_function (symbol, Qunbound);
+  set_symbol_function (symbol, Qnil);
   return symbol;
 }
 
@@ -580,9 +581,7 @@ DEFUN ("symbol-function", Fsymbol_function, Ssymbol_function, 1, 1, 0,
   (register Lisp_Object symbol)
 {
   CHECK_SYMBOL (symbol);
-  if (!EQ (XSYMBOL (symbol)->function, Qunbound))
     return XSYMBOL (symbol)->function;
-  xsignal1 (Qvoid_function, symbol);
 }
 
 DEFUN ("symbol-plist", Fsymbol_plist, Ssymbol_plist, 1, 1, 0,
@@ -613,7 +612,7 @@ DEFUN ("fset", Ffset, Sfset, 2, 2, 0,
 
   function = XSYMBOL (symbol)->function;
 
-  if (!NILP (Vautoload_queue) && !EQ (function, Qunbound))
+  if (!NILP (Vautoload_queue) && !NILP (function))
     Vautoload_queue = Fcons (Fcons (symbol, function), Vautoload_queue);
 
   if (AUTOLOADP (function))
@@ -714,7 +713,7 @@ Value, if non-nil, is a list \(interactive SPEC).  */)
 {
   Lisp_Object fun = indirect_function (cmd); /* Check cycles.  */
 
-  if (NILP (fun) || EQ (fun, Qunbound))
+  if (NILP (fun))
     return Qnil;
 
   /* Use an `interactive-form' property if present, analogous to the
@@ -2008,10 +2007,10 @@ indirect_function (register Lisp_Object object)
 
   for (;;)
     {
-      if (!SYMBOLP (hare) || EQ (hare, Qunbound))
+      if (!SYMBOLP (hare) || NILP (hare))
         break;
       hare = XSYMBOL (hare)->function;
-      if (!SYMBOLP (hare) || EQ (hare, Qunbound))
+      if (!SYMBOLP (hare) || NILP (hare))
         break;
       hare = XSYMBOL (hare)->function;
 
@@ -2038,10 +2037,10 @@ function chain of symbols.  */)
 
   /* Optimize for no indirection.  */
   result = object;
-  if (SYMBOLP (result) && !EQ (result, Qunbound)
+  if (SYMBOLP (result) && !NILP (result)
       && (result = XSYMBOL (result)->function, SYMBOLP (result)))
     result = indirect_function (result);
-  if (!EQ (result, Qunbound))
+  if (!NILP (result))
     return result;
 
   if (NILP (noerror))
diff --git a/src/eval.c b/src/eval.c
index f8a76646352..34b20f6fc8e 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -114,7 +114,6 @@ Lisp_Object Vsignaling_function;
 Lisp_Object inhibit_lisp_code;
 
 static Lisp_Object funcall_lambda (Lisp_Object, ptrdiff_t, Lisp_Object *);
-static bool interactive_p (void);
 static Lisp_Object apply_lambda (Lisp_Object fun, Lisp_Object args);
 
 /* Functions to set Lisp_Object slots of struct specbinding.  */
@@ -489,102 +488,6 @@ usage: (function ARG)  */)
 }
 
 
-DEFUN ("interactive-p", Finteractive_p, Sinteractive_p, 0, 0, 0,
-       doc: /* Return t if the containing function was run directly by user input.
-This means that the function was called with `call-interactively'
-\(which includes being called as the binding of a key)
-and input is currently coming from the keyboard (not a keyboard macro),
-and Emacs is not running in batch mode (`noninteractive' is nil).
-
-The only known proper use of `interactive-p' is in deciding whether to
-display a helpful message, or how to display it.  If you're thinking
-of using it for any other purpose, it is quite likely that you're
-making a mistake.  Think: what do you want to do when the command is
-called from a keyboard macro?
-
-To test whether your function was called with `call-interactively',
-either (i) add an extra optional argument and give it an `interactive'
-spec that specifies non-nil unconditionally (such as \"p\"); or (ii)
-use `called-interactively-p'.  */)
-  (void)
-{
-  return (INTERACTIVE && interactive_p ()) ? Qt : Qnil;
-}
-
-
-DEFUN ("called-interactively-p", Fcalled_interactively_p, Scalled_interactively_p, 0, 1, 0,
-       doc: /* Return t if the containing function was called by `call-interactively'.
-If KIND is `interactive', then only return t if the call was made
-interactively by the user, i.e. not in `noninteractive' mode nor
-when `executing-kbd-macro'.
-If KIND is `any', on the other hand, it will return t for any kind of
-interactive call, including being called as the binding of a key, or
-from a keyboard macro, or in `noninteractive' mode.
-
-The only known proper use of `interactive' for KIND is in deciding
-whether to display a helpful message, or how to display it.  If you're
-thinking of using it for any other purpose, it is quite likely that
-you're making a mistake.  Think: what do you want to do when the
-command is called from a keyboard macro?
-
-Instead of using this function, it is sometimes cleaner to give your
-function an extra optional argument whose `interactive' spec specifies
-non-nil unconditionally (\"p\" is a good way to do this), or via
-\(not (or executing-kbd-macro noninteractive)).  */)
-  (Lisp_Object kind)
-{
-  return (((INTERACTIVE || !EQ (kind, intern ("interactive")))
-           && interactive_p ())
-          ? Qt : Qnil);
-}
-
-
-/* Return true if function in which this appears was called using
-   call-interactively and is not a built-in.  */
-
-static bool
-interactive_p (void)
-{
-  struct backtrace *btp;
-  Lisp_Object fun;
-
-  btp = backtrace_list;
-
-  /* If this isn't a byte-compiled function, there may be a frame at
-     the top for Finteractive_p.  If so, skip it.  */
-  fun = Findirect_function (btp->function, Qnil);
-  if (SUBRP (fun) && (XSUBR (fun) == &Sinteractive_p
-                      || XSUBR (fun) == &Scalled_interactively_p))
-    btp = btp->next;
-
-  /* If we're running an Emacs 18-style byte-compiled function, there
-     may be a frame for Fbytecode at the top level.  In any version of
-     Emacs there can be Fbytecode frames for subexpressions evaluated
-     inside catch and condition-case.  Skip past them.
-
-     If this isn't a byte-compiled function, then we may now be
-     looking at several frames for special forms.  Skip past them.  */
-  while (btp
-         && (EQ (btp->function, Qbytecode)
-             || btp->nargs == UNEVALLED))
-    btp = btp->next;
-
-  /* `btp' now points at the frame of the innermost function that isn't
-     a special form, ignoring frames for Finteractive_p and/or
-     Fbytecode at the top.  If this frame is for a built-in function
-     (such as load or eval-region) return false.  */
-  fun = Findirect_function (btp->function, Qnil);
-  if (SUBRP (fun))
-    return 0;
-
-  /* `btp' points to the frame of a Lisp function that called interactive-p.
-     Return t if that function was called interactively.  */
-  if (btp && btp->next && EQ (btp->next->function, Qcall_interactively))
-    return 1;
-  return 0;
-}
-
-
 DEFUN ("defvaralias", Fdefvaralias, Sdefvaralias, 2, 3, 0,
        doc: /* Make NEW-ALIAS a variable alias for symbol BASE-VARIABLE.
 Aliased variables always have the same value; setting one sets the other.
@@ -696,8 +599,9 @@ usage: (defvar SYMBOL &optional INITVALUE DOCSTRING)  */)
               if (EQ ((--pdl)->symbol, sym) && !pdl->func
                   && EQ (pdl->old_value, Qunbound))
                 {
-                  message_with_string ("Warning: defvar ignored because %s is let-bound",
-                                       SYMBOL_NAME (sym), 1);
+                  message_with_string
+                    ("Warning: defvar ignored because %s is let-bound",
+                     SYMBOL_NAME (sym), 1);
                   break;
                 }
             }
@@ -717,8 +621,8 @@ usage: (defvar SYMBOL &optional INITVALUE DOCSTRING)  */)
     /* A simple (defvar foo) with lexical scoping does "nothing" except
        declare that var to be dynamically scoped *locally* (i.e. within
        the current file or let-block).  */
-    Vinternal_interpreter_environment =
-      Fcons (sym, Vinternal_interpreter_environment);
+    Vinternal_interpreter_environment
+      = Fcons (sym, Vinternal_interpreter_environment);
   else
     {
       /* Simple (defvar <var>) should not count as a definition at all.
@@ -971,7 +875,7 @@ definitions to shadow the loaded ones for use in file byte-compilation.  */)
           if (NILP (tem))
             {
               def = XSYMBOL (sym)->function;
-              if (!EQ (def, Qunbound))
+              if (!NILP (def))
                 continue;
             }
           break;
@@ -986,7 +890,7 @@ definitions to shadow the loaded ones for use in file byte-compilation.  */)
           GCPRO1 (form);
           def = Fautoload_do_load (def, sym, Qmacro);
           UNGCPRO;
-          if (EQ (def, Qunbound) || !CONSP (def))
+          if (!CONSP (def))
             /* Not defined or definition not suitable.  */
             break;
           if (!EQ (XCAR (def), Qmacro))
@@ -1811,12 +1715,12 @@ then strings and vectors are not accepted.  */)
 
   fun = function;
 
-  fun = indirect_function (fun); /* Check cycles. */
-  if (NILP (fun) || EQ (fun, Qunbound))
+  fun = indirect_function (fun); /* Check cycles.  */
+  if (NILP (fun))
     return Qnil;
 
   /* Check an `interactive-form' property if present, analogous to the
-     function-documentation property. */
+     function-documentation property.  */
   fun = function;
   while (SYMBOLP (fun))
     {
@@ -1876,7 +1780,7 @@ this does nothing and returns nil.  */)
   CHECK_STRING (file);
 
   /* If function is defined and not as an autoload, don't override.  */
-  if (!EQ (XSYMBOL (function)->function, Qunbound)
+  if (!NILP (XSYMBOL (function)->function)
       && !AUTOLOADP (XSYMBOL (function)->function))
     return Qnil;
 
@@ -2055,7 +1959,7 @@ eval_sub (Lisp_Object form)
 
   /* Optimize for no indirection.  */
   fun = original_fun;
-  if (SYMBOLP (fun) && !EQ (fun, Qunbound)
+  if (SYMBOLP (fun) && !NILP (fun)
       && (fun = XSYMBOL (fun)->function, SYMBOLP (fun)))
     fun = indirect_function (fun);
 
@@ -2177,7 +2081,7 @@ eval_sub (Lisp_Object form)
     val = apply_lambda (fun, original_args);
   else
     {
-      if (EQ (fun, Qunbound))
+      if (NILP (fun))
         xsignal1 (Qvoid_function, original_fun);
       if (!CONSP (fun))
         xsignal1 (Qinvalid_function, original_fun);
@@ -2251,10 +2155,10 @@ usage: (apply FUNCTION &rest ARGUMENTS)  */)
   numargs += nargs - 2;
 
   /* Optimize for no indirection.  */
-  if (SYMBOLP (fun) && !EQ (fun, Qunbound)
+  if (SYMBOLP (fun) && !NILP (fun)
       && (fun = XSYMBOL (fun)->function, SYMBOLP (fun)))
     fun = indirect_function (fun);
-  if (EQ (fun, Qunbound))
+  if (NILP (fun))
     {
       /* Let funcall get the error.  */
       fun = args[0];
@@ -2728,7 +2632,7 @@ usage: (funcall FUNCTION &rest ARGUMENTS)  */)
 
   /* Optimize for no indirection.  */
   fun = original_fun;
-  if (SYMBOLP (fun) && !EQ (fun, Qunbound)
+  if (SYMBOLP (fun) && !NILP (fun)
       && (fun = XSYMBOL (fun)->function, SYMBOLP (fun)))
     fun = indirect_function (fun);
 
@@ -2816,7 +2720,7 @@ usage: (funcall FUNCTION &rest ARGUMENTS)  */)
     val = funcall_lambda (fun, numargs, args + 1);
   else
     {
-      if (EQ (fun, Qunbound))
+      if (NILP (fun))
         xsignal1 (Qvoid_function, original_fun);
       if (!CONSP (fun))
         xsignal1 (Qinvalid_function, original_fun);
@@ -3551,8 +3455,6 @@ alist of active lexical bindings.  */);
   defsubr (&Sunwind_protect);
   defsubr (&Scondition_case);
   defsubr (&Ssignal);
-  defsubr (&Sinteractive_p);
-  defsubr (&Scalled_interactively_p);
   defsubr (&Scommandp);
   defsubr (&Sautoload);
   defsubr (&Sautoload_do_load);
diff --git a/src/lisp.h b/src/lisp.h
index 4941f649e79..ae532eed5a2 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -1109,7 +1109,7 @@ struct Lisp_Symbol
     union Lisp_Fwd *fwd;
   } val;
 
-  /* Function value of the symbol or Qunbound if not fboundp.  */
+  /* Function value of the symbol or Qnil if not fboundp.  */
   Lisp_Object function;
 
   /* The symbol's property list.  */
diff --git a/src/lread.c b/src/lread.c
index 5859a2f85a9..6d0ff9f780e 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -3957,12 +3957,13 @@ init_obarray (void)
   /* Fmake_symbol inits fields of new symbols with Qunbound and Qnil,
      so those two need to be fixed manually.  */
   SET_SYMBOL_VAL (XSYMBOL (Qunbound), Qunbound);
-  set_symbol_function (Qunbound, Qunbound);
+  set_symbol_function (Qunbound, Qnil);
   set_symbol_plist (Qunbound, Qnil);
   SET_SYMBOL_VAL (XSYMBOL (Qnil), Qnil);
   XSYMBOL (Qnil)->constant = 1;
   XSYMBOL (Qnil)->declared_special = 1;
   set_symbol_plist (Qnil, Qnil);
+  set_symbol_function (Qnil, Qnil);
 
   Qt = intern_c_string ("t");
   SET_SYMBOL_VAL (XSYMBOL (Qt), Qt);
diff --git a/src/w32fns.c b/src/w32fns.c
index ed5625e802c..90f5b1695ea 100644
--- a/src/w32fns.c
+++ b/src/w32fns.c
@@ -6167,9 +6167,9 @@ Otherwise, if ONLY-DIR-P is non-nil, the user can only select directories.  */)
       filename = empty_unibyte_string;
 
 #ifdef CYGWIN
-    dir = Fcygwin_convert_path_to_windows (dir, Qt);
+    dir = Fcygwin_convert_file_name_to_windows (dir, Qt);
     if (SCHARS (filename) > 0)
-      filename = Fcygwin_convert_path_to_windows (filename, Qnil);
+      filename = Fcygwin_convert_file_name_to_windows (filename, Qnil);
 #endif
 
     CHECK_STRING (dir);
@@ -6270,7 +6270,7 @@ Otherwise, if ONLY-DIR-P is non-nil, the user can only select directories.  */)
 #endif /* NTGUI_UNICODE */
 
 #ifdef CYGWIN
-        filename = Fcygwin_convert_path_from_windows (filename, Qt);
+        filename = Fcygwin_convert_file_name_from_windows (filename, Qt);
 #endif /* CYGWIN */
 
         /* Strip the dummy filename off the end of the string if we
diff --git a/src/xdisp.c b/src/xdisp.c
index 5e53168cf0e..a14c54dfc23 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -517,9 +517,8 @@ Lisp_Object Qmenu_bar_update_hook;
 
 static int overlay_arrow_seen;
 
-/* Number of windows showing the buffer of the selected window (or
-   another buffer with the same base buffer).  keyboard.c refers to
-   this.  */
+/* Number of windows showing the buffer of the selected
+   window (or another buffer with the same base buffer).  */
 
 int buffer_shared;
 
@@ -10943,8 +10942,26 @@ echo_area_display (int update_frame_p)
   return window_height_changed_p;
 }
 
+/* Nonzero if the current buffer is shown in more than
+   one window and was modified since last display.  */
+
+static int
+buffer_shared_and_changed (void)
+{
+  return (buffer_shared > 1 && UNCHANGED_MODIFIED < MODIFF);
+}
+
+/* Nonzero if W doesn't reflect the actual state of
+   current buffer due to its text or overlays change.  */
+
+static int
+window_outdated (struct window *w)
+{
+  eassert (XBUFFER (w->buffer) == current_buffer);
+  return (w->last_modified < MODIFF 
+          || w->last_overlay_modified < OVERLAY_MODIFF);
+}
 
-
 /***********************************************************************
                      Mode Lines and Frame Titles
  ***********************************************************************/
@@ -11250,7 +11267,7 @@ prepare_menu_bars (void)
   /* Update the menu bar item lists, if appropriate.  This has to be
      done before any actual redisplay or generation of display lines.  */
   all_windows = (update_mode_lines
-                 || buffer_shared > 1
+                 || buffer_shared_and_changed ()
                  || windows_or_buffers_changed);
   if (all_windows)
     {
@@ -12670,8 +12687,7 @@ text_outside_line_unchanged_p (struct window *w,
   int unchanged_p = 1;
 
   /* If text or overlays have changed, see where.  */
-  if (w->last_modified < MODIFF
-      || w->last_overlay_modified < OVERLAY_MODIFF)
+  if (window_outdated (w))
     {
       /* Gap in the line?  */
       if (GPT < start || Z - GPT < end)
@@ -13170,7 +13186,7 @@ redisplay_internal (void)
   if ((SAVE_MODIFF < MODIFF) != w->last_had_star)
     {
       w->update_mode_line = 1;
-      if (buffer_shared > 1)
+      if (buffer_shared_and_changed ())
         update_mode_lines++;
     }
 
@@ -13182,9 +13198,7 @@ redisplay_internal (void)
   if (!NILP (w->column_number_displayed)
       /* This alternative quickly identifies a common case
          where no change is needed.  */
-      && !(PT == w->last_point
-           && w->last_modified >= MODIFF
-           && w->last_overlay_modified >= OVERLAY_MODIFF)
+      && !(PT == w->last_point && !window_outdated (w))
       && (XFASTINT (w->column_number_displayed) != current_column ()))
     w->update_mode_line = 1;
 
@@ -13195,7 +13209,8 @@ redisplay_internal (void)
   /* The variable buffer_shared is set in redisplay_window and
      indicates that we redisplay a buffer in different windows.  See
      there.  */
-  consider_all_windows_p = (update_mode_lines || buffer_shared > 1
+  consider_all_windows_p = (update_mode_lines
+                            || buffer_shared_and_changed ()
                             || cursor_type_changed);
 
   /* If specs for an arrow have changed, do thorough redisplay
@@ -13245,18 +13260,16 @@ redisplay_internal (void)
         }
     }
   else if (EQ (selected_window, minibuf_window)
-           && (current_buffer->clip_changed
-               || w->last_modified < MODIFF
-               || w->last_overlay_modified < OVERLAY_MODIFF)
+           && (current_buffer->clip_changed || window_outdated (w))
            && resize_mini_window (w, 0))
     {
       /* Resized active mini-window to fit the size of what it is
          showing if its contents might have changed.  */
       must_finish = 1;
-/* FIXME: this causes all frames to be updated, which seems unnecessary
-   since only the current frame needs to be considered.  This function needs
-   to be rewritten with two variables, consider_all_windows and
-   consider_all_frames.  */
+      /* FIXME: this causes all frames to be updated, which seems unnecessary
+         since only the current frame needs to be considered.  This function
+         needs to be rewritten with two variables, consider_all_windows and
+         consider_all_frames.  */
       consider_all_windows_p = 1;
       ++windows_or_buffers_changed;
       ++update_mode_lines;
@@ -13311,9 +13324,7 @@ redisplay_internal (void)
               || FETCH_BYTE (BYTEPOS (tlbufpos)) == '\n'))
         /* Former continuation line has disappeared by becoming empty.  */
         goto cancel;
-      else if (w->last_modified < MODIFF
-               || w->last_overlay_modified < OVERLAY_MODIFF
-               || MINI_WINDOW_P (w))
+      else if (window_outdated (w) || MINI_WINDOW_P (w))
         {
           /* We have to handle the case of continuation around a
              wide-column character (see the comment in indent.c around
@@ -13494,7 +13505,7 @@ redisplay_internal (void)
     }
 
   CHARPOS (this_line_start_pos) = 0;
-  consider_all_windows_p |= buffer_shared > 1;
+  consider_all_windows_p |= buffer_shared_and_changed ();
   ++clear_face_cache_count;
 #ifdef HAVE_WINDOW_SYSTEM
   ++clear_image_cache_count;
@@ -15571,8 +15582,7 @@ redisplay_window (Lisp_Object window, int just_this_one_p)
     = (!NILP (w->window_end_valid)
        && !current_buffer->clip_changed
        && !current_buffer->prevent_redisplay_optimizations_p
-       && w->last_modified >= MODIFF
-       && w->last_overlay_modified >= OVERLAY_MODIFF);
+       && !window_outdated (w));
 
   /* Run the window-bottom-change-functions
      if it is possible that the text on the screen has changed
@@ -15594,8 +15604,7 @@ redisplay_window (Lisp_Object window, int just_this_one_p)
   buffer_unchanged_p
     = (!NILP (w->window_end_valid)
        && !current_buffer->clip_changed
-       && w->last_modified >= MODIFF
-       && w->last_overlay_modified >= OVERLAY_MODIFF);
+       && !window_outdated (w));
 
   /* When windows_or_buffers_changed is non-zero, we can't rely on
      the window end being valid, so set it to nil there.  */
@@ -15620,9 +15629,7 @@ redisplay_window (Lisp_Object window, int just_this_one_p)
   if (!NILP (w->column_number_displayed)
       /* This alternative quickly identifies a common case
          where no change is needed.  */
-      && !(PT == w->last_point
-           && w->last_modified >= MODIFF
-           && w->last_overlay_modified >= OVERLAY_MODIFF)
+      && !(PT == w->last_point && !window_outdated (w))
       && (XFASTINT (w->column_number_displayed) != current_column ()))
     update_mode_line = 1;
 
@@ -15864,8 +15871,7 @@ redisplay_window (Lisp_Object window, int just_this_one_p)
            && (CHARPOS (startp) < ZV
                /* Avoid starting at end of buffer.  */
                || CHARPOS (startp) == BEGV
-               || (w->last_modified >= MODIFF
-                   && w->last_overlay_modified >= OVERLAY_MODIFF)))
+               || !window_outdated (w)))
     {
       int d1, d2, d3, d4, d5, d6;