From 7295c6a871f9cc42a4209a8eebe2e0974194a2a3 Mon Sep 17 00:00:00 2001
From: Benjamin Peterson <benjamin@python.org>
Date: Tue, 1 May 2012 09:51:09 -0400
Subject: fix calling the classmethod descriptor directly (closes #14699)

---
 Lib/test/test_descr.py | 16 ++++++++++++++++
 Misc/NEWS              |  2 ++
 Objects/descrobject.c  | 44 +++++++++++++++++++++++++++++++++++++++++---
 3 files changed, 59 insertions(+), 3 deletions(-)

diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index 2289f6e..cdaf7d2 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -1458,6 +1458,22 @@ order (MRO) for bases """
         self.assertEqual(x, spam.spamlist)
         self.assertEqual(a, a1)
         self.assertEqual(d, d1)
+        spam_cm = spam.spamlist.__dict__['classmeth']
+        x2, a2, d2 = spam_cm(spam.spamlist, *a, **d)
+        self.assertEqual(x2, spam.spamlist)
+        self.assertEqual(a2, a1)
+        self.assertEqual(d2, d1)
+        class SubSpam(spam.spamlist): pass
+        x2, a2, d2 = spam_cm(SubSpam, *a, **d)
+        self.assertEqual(x2, SubSpam)
+        self.assertEqual(a2, a1)
+        self.assertEqual(d2, d1)
+        with self.assertRaises(TypeError):
+            spam_cm()
+        with self.assertRaises(TypeError):
+            spam_cm(spam.spamlist())
+        with self.assertRaises(TypeError):
+            spam_cm(list)
 
     def test_staticmethods(self):
         # Testing static methods...
diff --git a/Misc/NEWS b/Misc/NEWS
index c9752f6..c24caac 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,8 @@ What's New in Python 3.2.4
 Core and Builtins
 -----------------
 
+- Issue #14699: Fix calling the classmethod descriptor directly.
+
 - Issue #14433: Prevent msvcrt crash in interactive prompt when stdin
   is closed.
 
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index a786bae..9934f23 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -256,14 +256,52 @@ static PyObject *
 classmethoddescr_call(PyMethodDescrObject *descr, PyObject *args,
                       PyObject *kwds)
 {
-    PyObject *func, *result;
+    Py_ssize_t argc;
+    PyObject *self, *func, *result;
 
-    func = PyCFunction_New(descr->d_method, (PyObject *)PyDescr_TYPE(descr));
-    if (func == NULL)
+    /* Make sure that the first argument is acceptable as 'self' */
+    assert(PyTuple_Check(args));
+    argc = PyTuple_GET_SIZE(args);
+    if (argc < 1) {
+        PyErr_Format(PyExc_TypeError,
+                     "descriptor '%V' of '%.100s' "
+                     "object needs an argument",
+                     descr_name((PyDescrObject *)descr), "?",
+                     PyDescr_TYPE(descr)->tp_name);
         return NULL;
+    }
+    self = PyTuple_GET_ITEM(args, 0);
+    if (!PyType_Check(self)) {
+        PyErr_Format(PyExc_TypeError,
+                     "descriptor '%V' requires a type "
+                     "but received a '%.100s'",
+                     descr_name((PyDescrObject *)descr), "?",
+                     PyDescr_TYPE(descr)->tp_name,
+                     self->ob_type->tp_name);
+        return NULL;
+    }
+    if (!PyType_IsSubtype((PyTypeObject *)self, PyDescr_TYPE(descr))) {
+        PyErr_Format(PyExc_TypeError,
+                     "descriptor '%V' "
+                     "requires a subtype of '%.100s' "
+                     "but received '%.100s",
+                     descr_name((PyDescrObject *)descr), "?",
+                     PyDescr_TYPE(descr)->tp_name,
+                     self->ob_type->tp_name);
+        return NULL;
+    }
 
+    func = PyCFunction_New(descr->d_method, self);
+    if (func == NULL)
+        return NULL;
+    args = PyTuple_GetSlice(args, 1, argc);
+    if (args == NULL) {
+        Py_DECREF(func);
+        return NULL;
+    }
     result = PyEval_CallObjectWithKeywords(func, args, kwds);
     Py_DECREF(func);
+    Py_DECREF(args);
     return result;
 }
 
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