Make ctypes.Array abstract (#6361)

Co-authored-by: Akuli <akuviljanen17@gmail.com>

Author: sobolevn

stdlib/ctypes/__init__.pyi

@@ -1,5 +1,6 @@
 import sys
 from _typeshed import ReadableBuffer, WriteableBuffer
+from abc import abstractmethod
 from typing import (
     Any,
     Callable,
@@ -268,8 +269,16 @@ class BigEndianStructure(Structure): ...
 class LittleEndianStructure(Structure): ...
 
 class Array(Generic[_CT], _CData):
-    _length_: int
-    _type_: Type[_CT]
+    @property
+    @abstractmethod
+    def _length_(self) -> int: ...
+    @_length_.setter
+    def _length_(self, value: int) -> None: ...
+    @property
+    @abstractmethod
+    def _type_(self) -> Type[_CT]: ...
+    @_type_.setter
+    def _type_(self, value: Type[_CT]) -> None: ...
     raw: bytes  # Note: only available if _CT == c_char
     value: Any  # Note: bytes if _CT == c_char, str if _CT == c_wchar, unavailable otherwise
     # TODO These methods cannot be annotated correctly at the moment.

tests/stubtest_allowlists/py3_common.txt

@@ -73,6 +73,8 @@ csv.Dialect.lineterminator
 csv.Dialect.quoting
 csv.Dialect.skipinitialspace
 ctypes.Array.__iter__  # mypy doesn't support using __getitem__ instead of __iter__ so this is here https://github.com/python/mypy/issues/2220
+ctypes.Array._type_  # _type_ and _length_ are abstract, https://github.com/python/typeshed/pull/6361
+ctypes.Array._length_
 ctypes.CDLL._FuncPtr  # None at class level but initialized in __init__ to this value
 ctypes.memmove  # CFunctionType
 ctypes.memset  # CFunctionType