use #nil and #t

3 files changed, 41 insertions, 22 deletions

diff --git a/src/data.c b/src/data.c
index 225ac10cac..426bae133a 100644
--- a/src/data.c
+++ b/src/data.c
@@ -38,6 +38,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "keymap.h"
 
 Lisp_Object Qnil, Qt, Qquote, Qlambda, Qunbound;
+Lisp_Object Qnil_, Qt_;
 static Lisp_Object Qsubr;
 Lisp_Object Qerror_conditions, Qerror_message, Qtop_level;
 Lisp_Object Qerror, Quser_error, Qquit, Qargs_out_of_range;
diff --git a/src/lisp.h b/src/lisp.h
index 3d5e7bed62..0143506736 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -297,13 +297,14 @@ DEFINE_GDB_SYMBOL_END (USE_LSB_TAG)
 #define lisp_h_INTEGERP(x) (SCM_I_INUMP (x))
 #define lisp_h_MARKERP(x) (MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Marker)
 #define lisp_h_MISCP(x) (SMOB_TYPEP (x, lisp_misc_tag))
-#define lisp_h_NILP(x) EQ (x, Qnil)
+#define lisp_h_NILP(x) (scm_is_lisp_false (x))
 #define lisp_h_SET_SYMBOL_VAL(sym, v) \
    (eassert ((sym)->redirect == SYMBOL_PLAINVAL), (sym)->val.value = (v))
 #define lisp_h_SYMBOL_CONSTANT_P(sym) (XSYMBOL (sym)->constant)
 #define lisp_h_SYMBOL_VAL(sym) \
    (eassert ((sym)->redirect == SYMBOL_PLAINVAL), (sym)->val.value)
-#define lisp_h_SYMBOLP(x) (x && scm_is_symbol (x))
+#define lisp_h_SYMBOLP(x) \
+  (x && (scm_is_symbol (x) || EQ (x, Qnil) || EQ (x, Qt)))
 #define lisp_h_VECTORLIKEP(x) (SMOB_TYPEP (x, lisp_vectorlike_tag))
 #define lisp_h_XCAR(c) (scm_car (c))
 #define lisp_h_XCDR(c) (scm_cdr (c))
@@ -649,11 +650,14 @@ INLINE Lisp_Object build_string (const char *);
 extern Lisp_Object symbol_module;
 extern Lisp_Object function_module;
 extern Lisp_Object plist_module;
+extern Lisp_Object Qt, Qnil, Qt_, Qnil_;
 
 INLINE struct Lisp_Symbol *
 XSYMBOL (Lisp_Object a)
 {
   Lisp_Object tem;
+  if (EQ (a, Qt)) a = Qt_;
+  if (EQ (a, Qnil)) a = Qnil_;
   eassert (SYMBOLP (a));
   tem = scm_variable_ref (scm_module_lookup (symbol_module, a));
   return scm_to_pointer (tem);
@@ -1373,6 +1377,8 @@ SET_SYMBOL_FWD (struct Lisp_Symbol *sym, union Lisp_Fwd *v)
 INLINE Lisp_Object
 SYMBOL_NAME (Lisp_Object sym)
 {
+  if (EQ (sym, Qnil)) sym = Qnil_;
+  if (EQ (sym, Qt)) sym = Qt_;
   return build_string (scm_to_locale_string (scm_symbol_to_string (sym)));
 }
 
@@ -1381,12 +1387,16 @@ SYMBOL_NAME (Lisp_Object sym)
 INLINE bool
 SYMBOL_INTERNED_P (Lisp_Object sym)
 {
+  if (EQ (sym, Qnil)) sym = Qnil_;
+  if (EQ (sym, Qt)) sym = Qt_;
   return scm_is_true (scm_symbol_interned_p (sym));
 }
 
 INLINE Lisp_Object
 SYMBOL_FUNCTION (Lisp_Object sym)
 {
+  if (EQ (sym, Qnil)) sym = Qnil_;
+  if (EQ (sym, Qt)) sym = Qt_;
   return scm_variable_ref (scm_module_lookup (function_module, sym));
 }
 
@@ -2734,18 +2744,24 @@ set_hash_value_slot (struct Lisp_Hash_Table *h, ptrdiff_t idx, Lisp_Object val)
 INLINE void
 set_symbol_function (Lisp_Object sym, Lisp_Object function)
 {
+  if (EQ (sym, Qnil)) sym = Qnil_;
+  if (EQ (sym, Qt)) sym = Qt_;
   scm_variable_set_x (scm_module_lookup (function_module, sym), function);
 }
 
 INLINE Lisp_Object
 symbol_plist (Lisp_Object sym)
 {
+  if (EQ (sym, Qnil)) sym = Qnil_;
+  if (EQ (sym, Qt)) sym = Qt_;
   return scm_variable_ref (scm_module_lookup (plist_module, sym));
 }
 
 INLINE void
 set_symbol_plist (Lisp_Object sym, Lisp_Object plist)
 {
+  if (EQ (sym, Qnil)) sym = Qnil_;
+  if (EQ (sym, Qt)) sym = Qt_;
   scm_variable_set_x (scm_module_lookup (plist_module, sym), plist);
 }
 
@@ -2819,6 +2835,7 @@ set_sub_char_table_contents (Lisp_Object table, ptrdiff_t idx, Lisp_Object val)
 }
 
 /* Defined in data.c.  */
+extern Lisp_Object Qnil_, Qt_;
 extern Lisp_Object Qquote, Qunbound;
 extern Lisp_Object Qerror_conditions, Qerror_message, Qtop_level;
 extern Lisp_Object Qerror, Qquit, Qargs_out_of_range;
diff --git a/src/lread.c b/src/lread.c
index 54542fef97..d883cda62f 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -3946,7 +3946,14 @@ oblookup (Lisp_Object obarray, register const char *ptr, ptrdiff_t size, ptrdiff
   sym = scm_find_symbol (string2, obhash (obarray));
   if (scm_is_true (sym)
       && scm_is_true (scm_module_variable (symbol_module, sym)))
-    return sym;
+    {
+      if (EQ (sym, Qnil_))
+        return Qnil;
+      else if (EQ (sym, Qt_))
+        return Qt;
+      else
+        return sym;
+    }
   else
     return make_number (0);
 }
@@ -4002,27 +4009,21 @@ init_obarray (void)
   obarrays = scm_make_hash_table (SCM_UNDEFINED);
   scm_hashq_set_x (obarrays, Vobarray, SCM_UNDEFINED);
 
-  Qunbound = Fmake_symbol (build_pure_c_string ("unbound"));
-  /* Set temporary dummy values to Qnil and Vpurify_flag to satisfy the
-     NILP (Vpurify_flag) check in intern_c_string.  */
-  Qnil = make_number (-1); Vpurify_flag = make_number (1);
-  Qnil = intern_c_string ("nil");
+  Qnil = SCM_ELISP_NIL;
+  Qt = SCM_BOOL_T;
+
+  Qnil_ = intern_c_string ("nil");
+  SET_SYMBOL_VAL (XSYMBOL (Qnil_), Qnil);
+  XSYMBOL (Qnil_)->constant = 1;
+  XSYMBOL (Qnil_)->declared_special = 1;
 
-  /* Fmake_symbol inits fields of new symbols with Qunbound and Qnil,
-     so those two need to be fixed manually.  */
+  Qt_ = intern_c_string ("t");
+  SET_SYMBOL_VAL (XSYMBOL (Qt_), Qt);
+  XSYMBOL (Qt_)->constant = 1;
+  XSYMBOL (Qt_)->declared_special = 1;
+
+  Qunbound = Fmake_symbol (build_pure_c_string ("unbound"));
   SET_SYMBOL_VAL (XSYMBOL (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);
-  XSYMBOL (Qnil)->declared_special = 1;
-  XSYMBOL (Qt)->constant = 1;
 
   /* Qt is correct even if CANNOT_DUMP.  loadup.el will set to nil at end.  */
   Vpurify_flag = Qt;