bpo-1617161: Make the hash and equality of methods not depending on the value of self. (GH-7848)

* The hash of BuiltinMethodType instances no longer depends on the hash
  of __self__. It depends now on the hash of id(__self__).
* The hash and equality of ModuleType and MethodWrapperType instances no
  longer depend on the hash and equality of __self__. They depend now on
  the hash and equality of id(__self__).
* MethodWrapperType instances no longer support ordering.

Lib/test/test_descr.py

@@ -4350,38 +4350,71 @@ order (MRO) for bases """
         else:
             self.fail("did not test __init__() for None return")
 
+    def assertNotOrderable(self, a, b):
+        with self.assertRaises(TypeError):
+            a < b
+        with self.assertRaises(TypeError):
+            a > b
+        with self.assertRaises(TypeError):
+            a <= b
+        with self.assertRaises(TypeError):
+            a >= b
+
     def test_method_wrapper(self):
         # Testing method-wrapper objects...
         # <type 'method-wrapper'> did not support any reflection before 2.5
-
-        # XXX should methods really support __eq__?
-
         l = []
-        self.assertEqual(l.__add__, l.__add__)
-        self.assertEqual(l.__add__, [].__add__)
-        self.assertNotEqual(l.__add__, [5].__add__)
-        self.assertNotEqual(l.__add__, l.__mul__)
+        self.assertTrue(l.__add__ == l.__add__)
+        self.assertFalse(l.__add__ != l.__add__)
+        self.assertFalse(l.__add__ == [].__add__)
+        self.assertTrue(l.__add__ != [].__add__)
+        self.assertFalse(l.__add__ == l.__mul__)
+        self.assertTrue(l.__add__ != l.__mul__)
+        self.assertNotOrderable(l.__add__, l.__add__)
         self.assertEqual(l.__add__.__name__, '__add__')
-        if hasattr(l.__add__, '__self__'):
-            # CPython
-            self.assertIs(l.__add__.__self__, l)
-            self.assertIs(l.__add__.__objclass__, list)
-        else:
-            # Python implementations where [].__add__ is a normal bound method
-            self.assertIs(l.__add__.im_self, l)
-            self.assertIs(l.__add__.im_class, list)
+        self.assertIs(l.__add__.__self__, l)
+        self.assertIs(l.__add__.__objclass__, list)
         self.assertEqual(l.__add__.__doc__, list.__add__.__doc__)
-        try:
-            hash(l.__add__)
-        except TypeError:
-            pass
-        else:
-            self.fail("no TypeError from hash([].__add__)")
+        # hash([].__add__) should not be based on hash([])
+        hash(l.__add__)
 
-        t = ()
-        t += (7,)
-        self.assertEqual(t.__add__, (7,).__add__)
-        self.assertEqual(hash(t.__add__), hash((7,).__add__))
+    def test_builtin_function_or_method(self):
+        # Not really belonging to test_descr, but introspection and
+        # comparison on <type 'builtin_function_or_method'> seems not
+        # to be tested elsewhere
+        l = []
+        self.assertTrue(l.append == l.append)
+        self.assertFalse(l.append != l.append)
+        self.assertFalse(l.append == [].append)
+        self.assertTrue(l.append != [].append)
+        self.assertFalse(l.append == l.pop)
+        self.assertTrue(l.append != l.pop)
+        self.assertNotOrderable(l.append, l.append)
+        self.assertEqual(l.append.__name__, 'append')
+        self.assertIs(l.append.__self__, l)
+        # self.assertIs(l.append.__objclass__, list) --- could be added?
+        self.assertEqual(l.append.__doc__, list.append.__doc__)
+        # hash([].append) should not be based on hash([])
+        hash(l.append)
+
+    def test_special_unbound_method_types(self):
+        # Testing objects of <type 'wrapper_descriptor'>...
+        self.assertTrue(list.__add__ == list.__add__)
+        self.assertFalse(list.__add__ != list.__add__)
+        self.assertFalse(list.__add__ == list.__mul__)
+        self.assertTrue(list.__add__ != list.__mul__)
+        self.assertNotOrderable(list.__add__, list.__add__)
+        self.assertEqual(list.__add__.__name__, '__add__')
+        self.assertIs(list.__add__.__objclass__, list)
+
+        # Testing objects of <type 'method_descriptor'>...
+        self.assertTrue(list.append == list.append)
+        self.assertFalse(list.append != list.append)
+        self.assertFalse(list.append == list.pop)
+        self.assertTrue(list.append != list.pop)
+        self.assertNotOrderable(list.append, list.append)
+        self.assertEqual(list.append.__name__, 'append')
+        self.assertIs(list.append.__objclass__, list)
 
     def test_not_implemented(self):
         # Testing NotImplemented...