diff -r 11a6ee1fd7e4 Lib/test/test_datetime.py
--- a/Lib/test/test_datetime.py	Sat Mar 21 00:16:14 2009 +0100
+++ b/Lib/test/test_datetime.py	Mon Mar 23 14:12:11 2009 -0500
@@ -3327,12 +3327,7 @@
         self.assertRaises(TypeError, lambda: as_date >= as_datetime)
         self.assertRaises(TypeError, lambda: as_datetime >= as_date)
 
-        # Neverthelss, comparison should work with the base-class (date)
-        # projection if use of a date method is forced.
-        self.assert_(as_date.__eq__(as_datetime))
-        different_day = (as_date.day + 1) % 20 + 1
-        self.assert_(not as_date.__eq__(as_datetime.replace(day=
-                                                     different_day)))
+        # [removed two tests here due to fix for issue 5516]
 
         # And date should compare with other subclasses of date.  If a
         # subclass wants to stop this, it's up to the subclass to do so.
@@ -3346,6 +3341,16 @@
         self.assertEqual(as_datetime, datetime_sc)
         self.assertEqual(datetime_sc, as_datetime)
 
+        # subclasses should have the same __eq__ behavior as date and datetime
+        class D(date):
+            pass
+        class DT(datetime):
+            pass
+        d = D(2008, 1, 1)
+        dt = DT(2008, 1, 1)
+        self.assertNotEqual(d, dt)
+        self.assertNotEqual(dt, d)
+
 def test_main():
     test_support.run_unittest(__name__)
 
diff -r 11a6ee1fd7e4 Modules/datetimemodule.c
--- a/Modules/datetimemodule.c	Sat Mar 21 00:16:14 2009 +0100
+++ b/Modules/datetimemodule.c	Mon Mar 23 14:12:11 2009 -0500
@@ -2575,10 +2575,15 @@
 {
 	int diff = 42;	/* nonsense */
 
-	if (PyDate_Check(other))
-		diff = memcmp(self->data, ((PyDateTime_Date *)other)->data,
-			      _PyDateTime_DATE_DATASIZE);
-
+	if (PyDate_Check(other)) {
+		if (PyDateTime_Check(other))
+			diff = 1;
+		else
+			diff = memcmp(self->data,
+				      ((PyDateTime_Date *)other)->data,
+				      _PyDateTime_DATE_DATASIZE);
+
+	}
 	else if (PyObject_HasAttrString(other, "timetuple")) {
 		/* A hook for other kinds of date objects. */
 		Py_INCREF(Py_NotImplemented);