move some stuffs related to Structure and Union from ctypes/__init__.pyi to _ctypes.pyi, as at runtime.

stdlib/_ctypes.pyi

@@ -1,7 +1,7 @@
 import sys
 from _typeshed import ReadableBuffer, WriteableBuffer
 from abc import abstractmethod
-from collections.abc import Iterable, Iterator, Mapping
+from collections.abc import Iterable, Iterator, Mapping, Sequence
 from ctypes import CDLL, _CArgObject, _PointerLike
 from typing import Any, Generic, TypeVar, overload
 from typing_extensions import Self, TypeAlias
@@ -66,6 +66,24 @@ class _SimpleCData(Generic[_T], _CData):
     # but we can't use overloads without creating many, many mypy false-positive errors
     def __init__(self, value: _T = ...) -> None: ...  # pyright: ignore[reportInvalidTypeVarUse]
 
+class _CField:
+    offset: int
+    size: int
+
+class _StructUnionMeta(_CDataMeta):
+    _fields_: Sequence[tuple[str, type[_CData]] | tuple[str, type[_CData], int]]
+    _pack_: int
+    _anonymous_: Sequence[str]
+    def __getattr__(self, name: str) -> _CField: ...
+
+class _StructUnionBase(_CData, metaclass=_StructUnionMeta):
+    def __init__(self, *args: Any, **kw: Any) -> None: ...
+    def __getattr__(self, name: str) -> Any: ...
+    def __setattr__(self, name: str, value: Any) -> None: ...
+
+class Union(_StructUnionBase): ...
+class Structure(_StructUnionBase): ...
+
 class Array(Generic[_CT], _CData):
     @property
     @abstractmethod

stdlib/ctypes/__init__.pyi

@@ -3,9 +3,14 @@ from _ctypes import (
     RTLD_GLOBAL as RTLD_GLOBAL,
     RTLD_LOCAL as RTLD_LOCAL,
     Array as Array,
+    Structure as Structure,
+    Union as Union,
     _CData as _CData,
     _CDataMeta as _CDataMeta,
+    _CField as _CField,
     _SimpleCData as _SimpleCData,
+    _StructUnionBase as _StructUnionBase,
+    _StructUnionMeta as _StructUnionMeta,
 )
 from collections.abc import Callable, Sequence
 from typing import Any, ClassVar, Generic, TypeVar, overload
@@ -216,23 +221,5 @@ if sys.platform == "win32":
     class HRESULT(_SimpleCData[int]): ...  # TODO undocumented
 
 class py_object(_CanCastTo, _SimpleCData[_T]): ...
-
-class _CField:
-    offset: int
-    size: int
-
-class _StructUnionMeta(_CDataMeta):
-    _fields_: Sequence[tuple[str, type[_CData]] | tuple[str, type[_CData], int]]
-    _pack_: int
-    _anonymous_: Sequence[str]
-    def __getattr__(self, name: str) -> _CField: ...
-
-class _StructUnionBase(_CData, metaclass=_StructUnionMeta):
-    def __init__(self, *args: Any, **kw: Any) -> None: ...
-    def __getattr__(self, name: str) -> Any: ...
-    def __setattr__(self, name: str, value: Any) -> None: ...
-
-class Union(_StructUnionBase): ...
-class Structure(_StructUnionBase): ...
 class BigEndianStructure(Structure): ...
 class LittleEndianStructure(Structure): ...

tests/stubtest_allowlists/py3_common.txt

@@ -339,8 +339,6 @@ _ctypes.POINTER
 _ctypes.PyObj_FromPtr
 _ctypes.Py_DECREF
 _ctypes.Py_INCREF
-_ctypes.Structure
-_ctypes.Union
 _ctypes.addressof
 _ctypes.alignment
 _ctypes.buffer_info