requested changes

Author: tom-pytel

Lib/test/test_type_params.py

@@ -1184,15 +1184,14 @@ def func2[X, Y](x: X | Y) -> X | Y: ...
 def func3[X, *Y, **Z](x: X, y: tuple[*Y], z: Z) -> X: ...
 def func4[X: int, Y: (bytes, str)](x: X, y: Y) -> X | Y: ...
 def func3b[X, *Y, **Z]() -> X: return Class3[X, Y, Z]()
-def func5[Baz](): return Class5[Baz]()
+def func5[Baz](): return Class1[Baz]()
 
 class Class1[X]: ...
 class Class2[X, Y]: ...
 class Class3[X, *Y, **Z]: ...
 class Class4[X: int, Y: (bytes, str)]: ...
-class Class5(Generic[T]): pass
-class Class6:
-    def meth[Baz](): return Class5[Baz]()
+class Class5:
+    def meth[Baz](): return Class1[Baz]()
 
 
 class TypeParamsPickleTest(unittest.TestCase):
@@ -1271,12 +1270,12 @@ def test_pickling_anonymous_typeparams(self):
             unpickled = pickle.loads(pickled)
             self.assertIs(unpickled, thing)
 
-        thing = Class6.meth()
+        thing = Class5.meth()
         pickled = pickle.dumps(thing)
         unpickled = pickle.loads(pickled)
         self.assertIs(unpickled.__orig_class__, thing.__orig_class__)
         self.assertIs(unpickled.__orig_class__.__args__[0],
-                      Class6.meth.__type_params__[0])
+                      Class5.meth.__type_params__[0])
 
 
 class TypeParamsWeakRefTest(unittest.TestCase):

Misc/NEWS.d/next/Core_and_Builtins/2025-01-29-15-32-02.gh-issue-129250.ExhmQQ.rst

@@ -1 +1 @@
-Allow pickle of instances of generic classes.
+Fix pickling of generic classes instances.

Modules/_typingmodule.c

@@ -49,18 +49,13 @@ _typing__restore_anonymous_typeparam_impl(PyObject *module, PyObject *owner,
                                           PyObject *index)
 /*[clinic end generated code: output=00baec27dbf8d2d9 input=2f048db28d8124fb]*/
 {
-    PyObject *ret = NULL;
     PyObject *type_params = PyObject_GetAttr(owner, &_Py_ID(__type_params__));
-
     if (type_params == NULL) {
-        goto done;
+        return NULL;
     }
-
-    ret = PyObject_GetItem(type_params, index);
-
-done:
-    Py_XDECREF(type_params);
-    return ret;
+    PyObject *res = PyObject_GetItem(type_params, index);
+    Py_DECREF(type_params);
+    return res;
 }