gh-155053: Address review comments

Author: BHUVANSH855

Lib/test/test_genericalias.py

@@ -1,8 +1,6 @@
 """Tests for C-implemented GenericAlias."""
 
 import unittest
-from test import support
-from test.support import import_helper
 import pickle
 from array import array
 import copy
@@ -64,11 +62,10 @@
 from string.templatelib import Template, Interpolation
 
 import typing
-from typing import TypeVar, TypeVarTuple, Unpack
+from typing import TypeVar, Unpack
 T = TypeVar('T')
 K = TypeVar('K')
 V = TypeVar('V')
-Ts = TypeVarTuple("Ts")
 
 _UNPACKED_TUPLES = [
     # Unpacked tuple using `*`
@@ -100,8 +97,6 @@
     tuple[*tuple[Unpack[tuple[int, ...]]]],
 ]
 
-_testcapi = import_helper.import_module("_testcapi")
-
 class BaseTest(unittest.TestCase):
     """Test basics."""
     generic_types = [type, tuple, list, dict, frozendict,
@@ -632,29 +627,6 @@ def test_gh150146(self):
                 with self.assertRaises(TypeError):
                     x[*typing.Mapping[..., ...]]
 
-    @support.nomemtest
-    def test_subs_tvars_nomemory(self):
-        alias = dict[str, tuple[*Ts]]
-        key = (int, str)
-
-        # Warm the code path to stabilize the allocation window.
-        # This injection point was determined experimentally for this build.
-        try:
-            dict[str, tuple[int, str]]
-        except Exception:
-            pass
-
-        _testcapi.set_nomemory(24, 25)
-        raised = False
-        try:
-            alias[key]
-        except MemoryError:
-            raised = True
-        finally:
-            _testcapi.remove_mem_hooks()
-
-        self.assertTrue(raised, "MemoryError not raised")
-
 
 class TypeIterationTests(unittest.TestCase):
     _UNITERABLE_TYPES = (list, tuple)

Objects/genericaliasobject.c

@@ -302,6 +302,8 @@ subs_tvars(PyObject *obj, PyObject *params,
                                     PyTuple_GET_SIZE(arg));
                     if (j < 0) {
                         Py_DECREF(subparams);
+                        /* tuple_extend() clears subargs on failure, so there is no
+                           reference left to decref here. */
                         return NULL;
                     }
                     continue;