5 files changed, 28 insertions, 7 deletions
diff --git a/ChangeLog b/ChangeLog
index ea99d23820..157ecaa4e9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+Sun Dec 21 17:29:00 2003  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* class.c (rb_check_inheritable): new function.  [ruby-dev:22316]
+
+	* intern.h: add prototype.
+
+	* eval.c (superclass): use rb_check_inheritable().
+
+	* object.c (rb_class_initialize): check argument validity.
+
 Sun Dec 21 16:25:10 2003  Tanaka Akira  <akr@m17n.org>
 
 	* lib/pathname.rb (Pathname#+): re-implemented to resolve ".." in
diff --git a/class.c b/class.c
index 666548dde3..29fe34a915 100644
--- a/class.c
+++ b/class.c
@@ -178,6 +178,19 @@ rb_define_class_id(id, super)
     return klass;
 }
 
+void
+rb_check_inheritable(super)
+    VALUE super;
+{
+    if (TYPE(super) != T_CLASS) {
+	rb_raise(rb_eTypeError, "superclass must be a Class (%s given)",
+		 rb_obj_classname(super));
+    }
+    if (RBASIC(super)->flags & FL_SINGLETON) {
+	rb_raise(rb_eTypeError, "can't make subclass of virtual class");
+    }
+}
+
 VALUE
 rb_class_inherited(super, klass)
     VALUE super, klass;
diff --git a/eval.c b/eval.c
index 10d52d6511..545d678be2 100644
--- a/eval.c
+++ b/eval.c
@@ -1699,13 +1699,7 @@ superclass(self, node)
 	}
 	JUMP_TAG(state);
     }
-    if (TYPE(val) != T_CLASS) {
-	rb_raise(rb_eTypeError, "superclass must be a Class (%s given)",
-		 rb_obj_classname(val));
-    }
-    if (FL_TEST(val, FL_SINGLETON)) {
-	rb_raise(rb_eTypeError, "can't make subclass of virtual class");
-    }
+    rb_check_inheritable(val);
 
     return val;
 }
diff --git a/intern.h b/intern.h
index 6cdba0840e..5d7e9e78f3 100644
--- a/intern.h
+++ b/intern.h
@@ -102,6 +102,7 @@ VALUE rb_class_init_copy _((VALUE, VALUE));
 VALUE rb_singleton_class_clone _((VALUE));
 void rb_singleton_class_attached _((VALUE,VALUE));
 VALUE rb_make_metaclass _((VALUE, VALUE));
+void rb_check_inheritable _((VALUE));
 VALUE rb_class_inherited _((VALUE, VALUE));
 VALUE rb_define_class_id _((ID, VALUE));
 VALUE rb_module_new _((void));
diff --git a/object.c b/object.c
index 355d1e4f61..fda6410274 100644
--- a/object.c
+++ b/object.c
@@ -776,6 +776,9 @@ rb_class_initialize(argc, argv, klass)
     if (rb_scan_args(argc, argv, "01", &super) == 0) {
 	super = rb_cObject;
     }
+    else {
+	rb_check_inheritable(super);
+    }
     RCLASS(klass)->super = super;
     rb_make_metaclass(klass, RBASIC(super)->klass);
     rb_mod_initialize(klass);