commit 871309c775fd4d72048bfaa31affd54f9934f7dd
author Inada Naoki <songofacandy@gmail.com> Tue Mar 26 18:26:33 2019 +0900
committer Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Tue Mar 26 02:26:33 2019 -0700
tree 74a8d1910e61d82b91bf5a0d16de147a6f5a5588
parent b4d8f28a8af4f35c951c13a5c29630d1fb401105

bpo-36433: fix confusing error messages in classmethoddescr_call (GH-12556)



https://bugs.python.org/issue36433

Lib/test/test_descr.py

diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index e39fea6..09eef8c 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -1597,12 +1597,27 @@
         self.assertEqual(x2, SubSpam)
         self.assertEqual(a2, a1)
         self.assertEqual(d2, d1)
-        with self.assertRaises(TypeError):
+
+        with self.assertRaises(TypeError) as cm:
             spam_cm()
-        with self.assertRaises(TypeError):
+        self.assertEqual(
+            str(cm.exception),
+            "descriptor 'classmeth' of 'xxsubtype.spamlist' "
+            "object needs an argument")
+
+        with self.assertRaises(TypeError) as cm:
             spam_cm(spam.spamlist())
-        with self.assertRaises(TypeError):
+        self.assertEqual(
+            str(cm.exception),
+            "descriptor 'classmeth' requires a type "
+            "but received a 'xxsubtype.spamlist' instance")
+
+        with self.assertRaises(TypeError) as cm:
             spam_cm(list)
+        self.assertEqual(
+            str(cm.exception),
+            "descriptor 'classmeth' requires a subtype of 'xxsubtype.spamlist' "
+            "but received 'list'")
 
     def test_staticmethods(self):
         # Testing static methods...

Misc/NEWS.d/next/Core and Builtins/2019-03-26-17-23-02.bpo-36433.-8XzZf.rst

diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-03-26-17-23-02.bpo-36433.-8XzZf.rst b/Misc/NEWS.d/next/Core and Builtins/2019-03-26-17-23-02.bpo-36433.-8XzZf.rst
new file mode 100644
index 0000000..6d1bd28
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-03-26-17-23-02.bpo-36433.-8XzZf.rst
@@ -0,0 +1 @@
+Fixed TypeError message in classmethoddescr_call.

Objects/descrobject.c

diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index 22546a5..ab4151e 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -315,20 +315,18 @@
     if (!PyType_Check(self)) {
         PyErr_Format(PyExc_TypeError,
                      "descriptor '%V' requires a type "
-                     "but received a '%.100s'",
+                     "but received a '%.100s' instance",
                      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",
+                     "descriptor '%V' requires a subtype of '%.100s' "
+                     "but received '%.100s'",
                      descr_name((PyDescrObject *)descr), "?",
                      PyDescr_TYPE(descr)->tp_name,
-                     self->ob_type->tp_name);
+                     ((PyTypeObject*)self)->tp_name);
         return NULL;
     }