fix: classmethod __new__

Author: yanyongyu

Lib/inspect.py

@@ -1917,10 +1917,12 @@ def _signature_get_user_defined_method(cls, method_name, *, follow_wrapper_chain
     if meth is None:
         return None
 
+    unwrapped_meth = None
     if follow_wrapper_chains:
-        meth = unwrap(meth, stop=(lambda m: hasattr(m, "__signature__")
+        unwrapped_meth = unwrap(meth, stop=(lambda m: hasattr(m, "__signature__")
                                   or _signature_is_builtin(m)))
-    if isinstance(meth, _NonUserDefinedCallables):
+    if (isinstance(meth, _NonUserDefinedCallables)
+          or isinstance(unwrapped_meth, _NonUserDefinedCallables)):
         # Once '__signature__' will be added to 'C'-level
         # callables, this check won't be necessary
         return None

Lib/test/test_inspect/test_inspect.py

@@ -4154,17 +4154,17 @@ def __new__(cls, a):
                             ...))
 
         # TODO: classmethod is not correct
-        # with self.subTest('classmethod'):
-        #     class C:
-        #         @classmethod
-        #         @identity
-        #         def __new__(cls, cls2, a):
-        #             return a
-
-        #     self.assertEqual(C(1), 1)
-        #     self.assertEqual(self.signature(C),
-        #                     ((('a', ..., ..., "positional_or_keyword"),),
-        #                     ...))
+        with self.subTest('classmethod'):
+            class C:
+                @classmethod
+                @identity
+                def __new__(cls, cls2, a):
+                    return a
+
+            self.assertEqual(C(1), 1)
+            self.assertEqual(self.signature(C),
+                            ((('a', ..., ..., "positional_or_keyword"),),
+                            ...))
 
         with self.subTest('staticmethod'):
             class C:
@@ -4179,18 +4179,18 @@ def __new__(cls, a):
                             ...))
 
         # TODO: method type is not correct
-        # with self.subTest('MethodType'):
-        #     class A:
-        #         @identity
-        #         def call(self, cls, a):
-        #             return a
-        #     class C:
-        #         __new__ = A().call
-
-        #     self.assertEqual(C(1), 1)
-        #     self.assertEqual(self.signature(C),
-        #                     ((('a', ..., ..., "positional_or_keyword"),),
-        #                     ...))
+        with self.subTest('MethodType'):
+            class A:
+                @identity
+                def call(self, cls, a):
+                    return a
+            class C:
+                __new__ = A().call
+
+            self.assertEqual(C(1), 1)
+            self.assertEqual(self.signature(C),
+                            ((('a', ..., ..., "positional_or_keyword"),),
+                            ...))
 
         with self.subTest('partial'):
             class C: