Update types.SimpleNamespace for 3.13 (#12297)

stdlib/@tests/stubtest_allowlists/common.txt

@@ -500,7 +500,6 @@ types.MethodType.__closure__  # read-only but not actually a property; stubtest
 types.MethodType.__defaults__  # read-only but not actually a property; stubtest thinks it doesn't exist.
 types.ModuleType.__dict__  # read-only but not actually a property; stubtest thinks it's a mutable attribute.
 types.ModuleType.__getattr__  # this doesn't exist at runtime
-types.SimpleNamespace.__init__  # class doesn't accept positional arguments but has default C signature
 
 # sys attributes that are not always defined
 sys.gettotalrefcount  # Available on python debug builds

stdlib/@tests/stubtest_allowlists/py310.txt

@@ -249,6 +249,7 @@ pkgutil.ImpImporter\..*
 pkgutil.ImpLoader\..*
 
 types.CodeType.replace  # stubtest thinks default values are None but None doesn't work at runtime
+types.SimpleNamespace.__init__ # class doesn't accept positional arguments but has default C signature
 
 # These enums derive from (str, Enum)
 pstats.SortKey.__new__

stdlib/@tests/stubtest_allowlists/py311.txt

@@ -135,6 +135,7 @@ inspect._ParameterKind.description  # Still exists, but stubtest can't see it
 os.PathLike.__class_getitem__  # PathLike is a protocol; we don't expect all PathLike classes to implement class_getitem
 poplib.POP3_SSL.stls  # bad declaration of inherited function. See poplib.pyi
 types.GenericAlias.__call__  # Would be complicated to fix properly, Any could silence problems. #6392
+types.SimpleNamespace.__init__ # class doesn't accept positional arguments but has default C signature
 types.GenericAlias.__getattr__
 types.GenericAlias.__mro_entries__
 weakref.ProxyType.__reversed__  # Doesn't really exist

stdlib/@tests/stubtest_allowlists/py312.txt

@@ -184,6 +184,9 @@ typing.ParamSpecKwargs.__mro_entries__
 typing.TypeVar.__mro_entries__
 typing.TypeVarTuple.__mro_entries__
 
+# class doesn't accept positional arguments but has default C signature
+types.SimpleNamespace.__init__
+
 # TODO: mypy should infer that this attribute is inherited from builtins.type;
 # why doesn't it infer this?
 typing.SupportsAbs.__type_params__

stdlib/@tests/stubtest_allowlists/py38.txt

@@ -206,6 +206,7 @@ types.GetSetDescriptorType.__get__
 types.MemberDescriptorType.__get__
 types.MethodDescriptorType.__get__
 types.WrapperDescriptorType.__get__
+types.SimpleNamespace.__init__  # class doesn't accept positional arguments but has default C signature
 multiprocessing.managers.DictProxy.clear
 multiprocessing.managers.DictProxy.popitem
 

stdlib/@tests/stubtest_allowlists/py39.txt

@@ -223,6 +223,7 @@ pkgutil.ImpImporter\..*
 pkgutil.ImpLoader\..*
 
 types.CodeType.replace  # stubtest thinks default values are None but None doesn't work at runtime
+types.SimpleNamespace.__init__  # class doesn't accept positional arguments but has default C signature
 
 # These enums derive from (str, Enum)
 pstats.SortKey.__new__

stdlib/@tests/test_cases/check_types.py

@@ -0,0 +1,27 @@
+import sys
+import types
+from collections import UserDict
+
+# test `types.SimpleNamespace`
+
+# Valid:
+types.SimpleNamespace()
+types.SimpleNamespace(x=1, y=2)
+
+if sys.version_info >= (3, 13):
+    types.SimpleNamespace(())
+    types.SimpleNamespace([])
+    types.SimpleNamespace([("x", "y"), ("z", 1)])
+    types.SimpleNamespace({})
+    types.SimpleNamespace(UserDict({"x": 1, "y": 2}))
+
+
+# Invalid:
+types.SimpleNamespace(1)  # type: ignore
+types.SimpleNamespace([1])  # type: ignore
+types.SimpleNamespace([["x"]])  # type: ignore
+types.SimpleNamespace(**{1: 2})  # type: ignore
+types.SimpleNamespace({1: 2})  # type: ignore
+types.SimpleNamespace([[1, 2]])  # type: ignore
+types.SimpleNamespace(UserDict({1: 2}))  # type: ignore
+types.SimpleNamespace([[[], 2]])  # type: ignore