bpo-45664: Fix resolve_bases() and new_class() for GenericAlias instance as a base (GH-29298)
diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
index b1218ab..3dfda5c 100644
--- a/Lib/test/test_types.py
+++ b/Lib/test/test_types.py
@@ -1236,6 +1236,17 @@ def __mro_entries__(self, bases):
self.assertEqual(D.__orig_bases__, (c,))
self.assertEqual(D.__mro__, (D, A, object))
+ def test_new_class_with_mro_entry_genericalias(self):
+ L1 = types.new_class('L1', (typing.List[int],), {})
+ self.assertEqual(L1.__bases__, (list, typing.Generic))
+ self.assertEqual(L1.__orig_bases__, (typing.List[int],))
+ self.assertEqual(L1.__mro__, (L1, list, typing.Generic, object))
+
+ L2 = types.new_class('L2', (list[int],), {})
+ self.assertEqual(L2.__bases__, (list,))
+ self.assertEqual(L2.__orig_bases__, (list[int],))
+ self.assertEqual(L2.__mro__, (L2, list, object))
+
def test_new_class_with_mro_entry_none(self):
class A: pass
class B: pass
@@ -1351,6 +1362,11 @@ def __mro_entries__(self, bases):
for bases in [x, y, z, t]:
self.assertIs(types.resolve_bases(bases), bases)
+ def test_resolve_bases_with_mro_entry(self):
+ self.assertEqual(types.resolve_bases((typing.List[int],)),
+ (list, typing.Generic))
+ self.assertEqual(types.resolve_bases((list[int],)), (list,))
+
def test_metaclass_derivation(self):
# issue1294232: correct metaclass calculation
new_calls = [] # to check the order of __new__ calls
diff --git a/Lib/types.py b/Lib/types.py
index ce1c28d..679c7f6 100644
--- a/Lib/types.py
+++ b/Lib/types.py
@@ -82,7 +82,7 @@ def resolve_bases(bases):
updated = False
shift = 0
for i, base in enumerate(bases):
- if isinstance(base, type):
+ if isinstance(base, type) and not isinstance(base, GenericAlias):
continue
if not hasattr(base, "__mro_entries__"):
continue
diff --git a/Misc/NEWS.d/next/Library/2021-10-28-23-40-54.bpo-45664.7dqtxQ.rst b/Misc/NEWS.d/next/Library/2021-10-28-23-40-54.bpo-45664.7dqtxQ.rst
new file mode 100644
index 0000000..573a569
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-10-28-23-40-54.bpo-45664.7dqtxQ.rst
@@ -0,0 +1,2 @@
+Fix :func:`types.resolve_bases` and :func:`types.new_class` for
+:class:`types.GenericAlias` instance as a base.
