Make defvar affect the default binding outside of any let.

* src/eval.c (default_toplevel_binding): New function.
(Fdefvar): Use it.
(unbind_to, backtrace_eval_unrewind): Do a bit of CSE simplification.
(Fdefault_toplevel_value, Fset_default_toplevel_value): New subrs.
(syms_of_eval): Export them.
* src/data.c (Fdefault_value): Micro cleanup.
* src/term.c (init_tty): Use "false".
* lisp/custom.el (custom-initialize-default, custom-initialize-set)
(custom-initialize-reset, custom-initialize-changed): Affect the
toplevel-default-value (bug#6275, bug#14586).
* lisp/emacs-lisp/advice.el (ad-compile-function): Undo previous workaround
for bug#6275.
* test/automated/core-elisp-tests.el: New file.

4 files changed, 105 insertions, 57 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 2a511d2fc8a..c6e349010a7 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,13 @@
+2013-08-02  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+	* eval.c (default_toplevel_binding): New function.
+	(Fdefvar): Use it.
+	(unbind_to, backtrace_eval_unrewind): Do a bit of CSE simplification.
+	(Fdefault_toplevel_value, Fset_default_toplevel_value): New subrs.
+	(syms_of_eval): Export them.
+	* data.c (Fdefault_value): Micro cleanup.
+	* term.c (init_tty): Use "false".
+
 2013-08-02  Dmitry Antipov  <dmantipov@yandex.ru>
 
 	Fix X GC leak in GTK and raw (no toolkit) X ports.
diff --git a/src/data.c b/src/data.c
index f04d6da618f..d1e43ac1b5f 100644
--- a/src/data.c
+++ b/src/data.c
@@ -1384,9 +1384,7 @@ for this variable.  The default value is meaningful for variables with
 local bindings in certain buffers.  */)
   (Lisp_Object symbol)
 {
-  register Lisp_Object value;
-
-  value = default_value (symbol);
+  Lisp_Object value = default_value (symbol);
   if (!EQ (value, Qunbound))
     return value;
 
diff --git a/src/eval.c b/src/eval.c
index cb716690e3c..8ee259110f4 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -658,6 +658,51 @@ The return value is BASE-VARIABLE.  */)
   return base_variable;
 }
 
+static union specbinding *
+default_toplevel_binding (Lisp_Object symbol)
+{
+  union specbinding *binding = NULL;
+  union specbinding *pdl = specpdl_ptr;
+  while (pdl > specpdl)
+    {
+      switch ((--pdl)->kind)
+	{
+	case SPECPDL_LET_DEFAULT:
+	case SPECPDL_LET:
+	  if (EQ (specpdl_symbol (pdl), symbol))
+	    binding = pdl;
+	  break;
+	}
+    }
+  return binding;
+}
+
+DEFUN ("default-toplevel-value", Fdefault_toplevel_value, Sdefault_toplevel_value, 1, 1, 0,
+       doc: /* Return SYMBOL's toplevel default value.
+"Toplevel" means outside of any let binding.  */)
+  (Lisp_Object symbol)
+{
+  union specbinding *binding = default_toplevel_binding (symbol);
+  Lisp_Object value
+    = binding ? specpdl_old_value (binding) : Fdefault_value (symbol);
+  if (!EQ (value, Qunbound))
+    return value;
+  xsignal1 (Qvoid_variable, symbol);
+}
+
+DEFUN ("set-default-toplevel-value", Fset_default_toplevel_value,
+       Sset_default_toplevel_value, 2, 2, 0,
+       doc: /* Set SYMBOL's toplevel default value to VALUE.
+"Toplevel" means outside of any let binding.  */)
+     (Lisp_Object symbol, Lisp_Object value)
+{
+  union specbinding *binding = default_toplevel_binding (symbol);
+  if (binding)
+    set_specpdl_old_value (binding, value);
+  else
+    Fset_default (symbol, value);
+  return Qnil;
+}
 
 DEFUN ("defvar", Fdefvar, Sdefvar, 1, UNEVALLED, 0,
        doc: /* Define SYMBOL as a variable, and return SYMBOL.
@@ -706,18 +751,10 @@ usage: (defvar SYMBOL &optional INITVALUE DOCSTRING)  */)
       else
 	{ /* Check if there is really a global binding rather than just a let
 	     binding that shadows the global unboundness of the var.  */
-	  union specbinding *pdl = specpdl_ptr;
-	  while (pdl > specpdl)
+	  union specbinding *binding = default_toplevel_binding (sym);
+	  if (binding && EQ (specpdl_old_value (binding), Qunbound))
 	    {
-	      if ((--pdl)->kind >= SPECPDL_LET
-		  && EQ (specpdl_symbol (pdl), sym)
-		  && EQ (specpdl_old_value (pdl), Qunbound))
-		{
-		  message_with_string
-		    ("Warning: defvar ignored because %s is let-bound",
-		     SYMBOL_NAME (sym), 1);
-		  break;
-		}
+	      set_specpdl_old_value (binding, eval_sub (XCAR (tail)));
 	    }
 	}
       tail = XCDR (tail);
@@ -3311,19 +3348,21 @@ unbind_to (ptrdiff_t count, Lisp_Object value)
 	case SPECPDL_BACKTRACE:
 	  break;
 	case SPECPDL_LET:
-	  /* If variable has a trivial value (no forwarding), we can
-	     just set it.  No need to check for constant symbols here,
-	     since that was already done by specbind.  */
-	  if (XSYMBOL (specpdl_symbol (specpdl_ptr))->redirect
-	      == SYMBOL_PLAINVAL)
-	    SET_SYMBOL_VAL (XSYMBOL (specpdl_symbol (specpdl_ptr)),
-			    specpdl_old_value (specpdl_ptr));
-	  else
-	    /* NOTE: we only ever come here if make_local_foo was used for
-	       the first time on this var within this let.  */
-	    Fset_default (specpdl_symbol (specpdl_ptr),
-			  specpdl_old_value (specpdl_ptr));
-	  break;
+	  { /* If variable has a trivial value (no forwarding), we can
+	       just set it.  No need to check for constant symbols here,
+	       since that was already done by specbind.  */
+	    struct Lisp_Symbol *sym = XSYMBOL (specpdl_symbol (specpdl_ptr));
+	    if (sym->redirect == SYMBOL_PLAINVAL)
+	      {
+		SET_SYMBOL_VAL (sym, specpdl_old_value (specpdl_ptr));
+		break;
+	      }
+	    else
+	      { /* FALLTHROUGH!!
+		   NOTE: we only ever come here if make_local_foo was used for
+		   the first time on this var within this let.  */
+	      }
+	  }
 	case SPECPDL_LET_DEFAULT:
 	  Fset_default (specpdl_symbol (specpdl_ptr),
 			specpdl_old_value (specpdl_ptr));
@@ -3511,24 +3550,23 @@ backtrace_eval_unrewind (int distance)
 	case SPECPDL_BACKTRACE:
 	  break;
 	case SPECPDL_LET:
-	  /* If variable has a trivial value (no forwarding), we can
-	     just set it.  No need to check for constant symbols here,
-	     since that was already done by specbind.  */
-	  if (XSYMBOL (specpdl_symbol (tmp))->redirect
-	      == SYMBOL_PLAINVAL)
-	    {
-	      struct Lisp_Symbol *sym = XSYMBOL (specpdl_symbol (tmp));
-	      Lisp_Object old_value = specpdl_old_value (tmp);
-	      set_specpdl_old_value (tmp, SYMBOL_VAL (sym));
-	      SET_SYMBOL_VAL (sym, old_value);
-	      break;
-	    }
-	  else
-	    {
-	      /* FALLTHROUGH!
-		 NOTE: we only ever come here if make_local_foo was used for
-		 the first time on this var within this let.  */
-	    }
+	  { /* If variable has a trivial value (no forwarding), we can
+	       just set it.  No need to check for constant symbols here,
+	       since that was already done by specbind.  */
+	    struct Lisp_Symbol *sym = XSYMBOL (specpdl_symbol (tmp));
+	    if (sym->redirect == SYMBOL_PLAINVAL)
+	      {
+		Lisp_Object old_value = specpdl_old_value (tmp);
+		set_specpdl_old_value (tmp, SYMBOL_VAL (sym));
+		SET_SYMBOL_VAL (sym, old_value);
+		break;
+	      }
+	    else
+	      { /* FALLTHROUGH!!
+		   NOTE: we only ever come here if make_local_foo was used for
+		   the first time on this var within this let.  */
+	      }
+	  }
 	case SPECPDL_LET_DEFAULT:
 	  {
 	    Lisp_Object sym = specpdl_symbol (tmp);
@@ -3796,6 +3834,8 @@ alist of active lexical bindings.  */);
   defsubr (&Ssetq);
   defsubr (&Squote);
   defsubr (&Sfunction);
+  defsubr (&Sdefault_toplevel_value);
+  defsubr (&Sset_default_toplevel_value);
   defsubr (&Sdefvar);
   defsubr (&Sdefvaralias);
   defsubr (&Sdefconst);
diff --git a/src/term.c b/src/term.c
index 376d6e7831a..f5f4882161e 100644
--- a/src/term.c
+++ b/src/term.c
@@ -2933,7 +2933,7 @@ dissociate_if_controlling_tty (int fd)
 
    TERMINAL_TYPE is the termcap type of the device, e.g. "vt100".
 
-   If MUST_SUCCEED is true, then all errors are fatal. */
+   If MUST_SUCCEED is true, then all errors are fatal.  */
 
 struct terminal *
 init_tty (const char *name, const char *terminal_type, bool must_succeed)
@@ -2944,7 +2944,7 @@ init_tty (const char *name, const char *terminal_type, bool must_succeed)
   int status;
   struct tty_display_info *tty = NULL;
   struct terminal *terminal = NULL;
-  bool ctty = 0;  /* True if asked to open controlling tty.  */
+  bool ctty = false;  /* True if asked to open controlling tty.  */
 
   if (!terminal_type)
     maybe_fatal (must_succeed, 0,
@@ -3031,7 +3031,7 @@ init_tty (const char *name, const char *terminal_type, bool must_succeed)
   tty->termcap_term_buffer = xmalloc (buffer_size);
 
   /* On some systems, tgetent tries to access the controlling
-     terminal. */
+     terminal.  */
   block_tty_out_signal ();
   status = tgetent (tty->termcap_term_buffer, terminal_type);
   unblock_tty_out_signal ();
@@ -3101,13 +3101,13 @@ use the Bourne shell command `TERM=... export TERM' (C-shell:\n\
   Right (tty) = tgetstr ("nd", address);
   Down (tty) = tgetstr ("do", address);
   if (!Down (tty))
-    Down (tty) = tgetstr ("nl", address); /* Obsolete name for "do" */
+    Down (tty) = tgetstr ("nl", address); /* Obsolete name for "do".  */
   if (tgetflag ("bs"))
-    Left (tty) = "\b";		  /* can't possibly be longer! */
-  else				  /* (Actually, "bs" is obsolete...) */
+    Left (tty) = "\b";		  /* Can't possibly be longer!  */
+  else				  /* (Actually, "bs" is obsolete...)  */
     Left (tty) = tgetstr ("le", address);
   if (!Left (tty))
-    Left (tty) = tgetstr ("bc", address); /* Obsolete name for "le" */
+    Left (tty) = tgetstr ("bc", address); /* Obsolete name for "le".  */
   tty->TS_pad_char = tgetstr ("pc", address);
   tty->TS_repeat = tgetstr ("rp", address);
   tty->TS_end_standout_mode = tgetstr ("se", address);
@@ -3229,7 +3229,7 @@ use the Bourne shell command `TERM=... export TERM' (C-shell:\n\
      don't think we're losing anything by turning it off.  */
   terminal->line_ins_del_ok = 0;
 
-  tty->TN_max_colors = 16;  /* Required to be non-zero for tty-display-color-p */
+  tty->TN_max_colors = 16;  /* Must be non-zero for tty-display-color-p.  */
 #endif	/* DOS_NT */
 
 #ifdef HAVE_GPM
@@ -3325,16 +3325,16 @@ use the Bourne shell command `TERM=... export TERM' (C-shell:\n\
       tty->Wcm->cm_tab = 0;
       /* We can't support standout mode, because it uses magic cookies.  */
       tty->TS_standout_mode = 0;
-      /* But that means we cannot rely on ^M to go to column zero! */
+      /* But that means we cannot rely on ^M to go to column zero!  */
       CR (tty) = 0;
-      /* LF can't be trusted either -- can alter hpos */
-      /* if move at column 0 thru a line with TS_standout_mode */
+      /* LF can't be trusted either -- can alter hpos.  */
+      /* If move at column 0 thru a line with TS_standout_mode.  */
       Down (tty) = 0;
     }
 
   tty->specified_window = FrameRows (tty);
 
-  if (Wcm_init (tty) == -1)	/* can't do cursor motion */
+  if (Wcm_init (tty) == -1)	/* Can't do cursor motion.  */
     {
       maybe_fatal (must_succeed, terminal,
                    "Terminal type \"%s\" is not powerful enough to run Emacs",