Special-case class objects

Author: johnslavik

Lib/test/test_exceptions.py

@@ -2084,6 +2084,42 @@ def __getattr__(self, name):
         self.assertIs(cm.exception.obj, obj)
         self.assertEqual(cm.exception.name, "missing3")
 
+    def test_class_getattr_error_message(self):
+        def fqn(type):
+            return f'{type.__module__}.{type.__qualname__}'
+
+        class MetaclassRaiseWithName(type):
+            def __getattr__(self, name):
+                raise AttributeError(name)
+        cls = MetaclassRaiseWithName("spam", (), {})
+        with self.assertRaises(AttributeError) as cm:
+            getattr(cls, "missing1")
+        self.assertEqual(str(cm.exception),
+                         f"type object '{fqn(cls)}' has no attribute 'missing1'")
+        self.assertIs(cm.exception.obj, cls)
+        self.assertEqual(cm.exception.name, "missing1")
+
+        class MetaclassBareRaise(type):
+            def __getattr__(self, name):
+                raise AttributeError
+        cls = MetaclassBareRaise("eggs", (), {})
+        with self.assertRaises(AttributeError) as cm:
+            getattr(cls, "missing2")
+        self.assertEqual(str(cm.exception),
+                         f"type object '{fqn(cls)}' has no attribute 'missing2'")
+        self.assertIs(cm.exception.obj, cls)
+        self.assertEqual(cm.exception.name, "missing2")
+
+        class MetaclassRaiseCustom(type):
+            def __getattr__(self, name):
+                raise AttributeError("custom")
+        cls = MetaclassRaiseCustom("ham", (), {})
+        with self.assertRaises(AttributeError) as cm:
+            getattr(cls, "missing3")
+        self.assertEqual(str(cm.exception), "custom")
+        self.assertIs(cm.exception.obj, cls)
+        self.assertEqual(cm.exception.name, "missing3")
+
     def test_module_getattr_error_message(self):
         raisewithname_mod = ModuleType("raisewithname")
         def raise_with_name(name):

Objects/exceptions.c

@@ -2738,6 +2738,9 @@ AttributeError_str(PyObject *op)
         } else {
             result = PyUnicode_FromFormat("module has no attribute '%U'", name);
         }
+    } else if (PyType_Check(obj)) {
+        result = PyUnicode_FromFormat("type object '%N' has no attribute '%U'",
+                                      _PyType_CAST(obj), name);
     } else {
         result = PyUnicode_FromFormat("'%T' object has no attribute '%U'",
                                       obj, name);