Enable flake8-pyi's Y037

.flake8

@@ -18,20 +18,15 @@
 #     F403   import *' used; unable to detect undefined names
 #     F405   defined from star imports
 
-# Rules that we'd like to enable in the future:
-#     Y037   Use PEP 604 syntax instead of `typing.Union` and `typing.Optional`.
-#            Currently can't be enabled due to a few lingering bugs in mypy regarding
-#            PEP 604 type aliases (see #4819).
-
 [flake8]
 per-file-ignores =
   *.py: E203, E301, E302, E305, E501
-  *.pyi: B, E301, E302, E305, E501, E701, E741, F401, F403, F405, F822, Y037
+  *.pyi: B, E301, E302, E305, E501, E701, E741, F401, F403, F405, F822
   # Since typing.pyi defines "overload" this is not recognized by flake8 as typing.overload.
   # Unfortunately, flake8 does not allow to "noqa" just a specific error inside the file itself.
   # https://github.com/PyCQA/flake8/issues/1079
   #     F811 redefinition of unused '...'
-  stdlib/typing.pyi: B, E301, E302, E305, E501, E701, E741, F401, F403, F405, F811, F822, Y037
+  stdlib/typing.pyi: B, E301, E302, E305, E501, E701, E741, F401, F403, F405, F811, F822
   # Generated protobuf files include docstrings
   *_pb2.pyi: B, E301, E302, E305, E501, E701, Y021, Y026
 

stdlib/_csv.pyi

@@ -1,6 +1,6 @@
 from _typeshed import SupportsWrite
 from collections.abc import Iterable, Iterator
-from typing import Any, Union
+from typing import Any
 from typing_extensions import Literal, TypeAlias
 
 __version__: str
@@ -27,7 +27,7 @@ class Dialect:
     strict: bool
     def __init__(self) -> None: ...
 
-_DialectLike: TypeAlias = Union[str, Dialect, type[Dialect]]
+_DialectLike: TypeAlias = str | Dialect | type[Dialect]
 
 class _reader(Iterator[list[str]]):
     @property

stdlib/_decimal.pyi

@@ -3,11 +3,11 @@ import sys
 from _typeshed import Self
 from collections.abc import Container, Sequence
 from types import TracebackType
-from typing import Any, ClassVar, NamedTuple, Union, overload
+from typing import Any, ClassVar, NamedTuple, overload
 from typing_extensions import Literal, TypeAlias
 
 _Decimal: TypeAlias = Decimal | int
-_DecimalNew: TypeAlias = Union[Decimal, float, str, tuple[int, Sequence[int], int]]
+_DecimalNew: TypeAlias = Decimal | float | str | tuple[int, Sequence[int], int]
 _ComparableNum: TypeAlias = Decimal | float | numbers.Rational
 
 __version__: str

stdlib/_typeshed/__init__.pyi

@@ -11,7 +11,7 @@ from collections.abc import Awaitable, Callable, Iterable, Set as AbstractSet
 from dataclasses import Field
 from os import PathLike
 from types import FrameType, TracebackType
-from typing import Any, AnyStr, ClassVar, Generic, Protocol, TypeVar, Union
+from typing import Any, AnyStr, ClassVar, Generic, Protocol, TypeVar
 from typing_extensions import Final, Literal, LiteralString, TypeAlias, final
 
 _KT = TypeVar("_KT")
@@ -265,7 +265,7 @@ IndexableBuffer: TypeAlias = bytes | bytearray | memoryview | array.array[Any] |
 #     def __buffer__(self, __flags: int) -> memoryview: ...
 
 ExcInfo: TypeAlias = tuple[type[BaseException], BaseException, TracebackType]
-OptExcInfo: TypeAlias = Union[ExcInfo, tuple[None, None, None]]
+OptExcInfo: TypeAlias = ExcInfo | tuple[None, None, None]
 
 # stable
 if sys.version_info >= (3, 10):

stdlib/copyreg.pyi

@@ -1,9 +1,9 @@
 from collections.abc import Callable, Hashable
-from typing import Any, SupportsInt, TypeVar, Union
+from typing import Any, SupportsInt, TypeVar
 from typing_extensions import TypeAlias
 
 _T = TypeVar("_T")
-_Reduce: TypeAlias = Union[tuple[Callable[..., _T], tuple[Any, ...]], tuple[Callable[..., _T], tuple[Any, ...], Any | None]]
+_Reduce: TypeAlias = tuple[Callable[..., _T], tuple[Any, ...]] | tuple[Callable[..., _T], tuple[Any, ...], Any | None]
 
 __all__ = ["pickle", "constructor", "add_extension", "remove_extension", "clear_extension_cache"]
 

stdlib/ctypes/__init__.pyi

@@ -3,7 +3,7 @@ from _ctypes import RTLD_GLOBAL as RTLD_GLOBAL, RTLD_LOCAL as RTLD_LOCAL
 from _typeshed import ReadableBuffer, Self, WriteableBuffer
 from abc import abstractmethod
 from collections.abc import Callable, Iterable, Iterator, Mapping, Sequence
-from typing import Any, ClassVar, Generic, TypeVar, Union as _UnionT, overload
+from typing import Any, ClassVar, Generic, TypeVar, overload
 from typing_extensions import TypeAlias
 
 if sys.version_info >= (3, 9):
@@ -91,7 +91,7 @@ class _CanCastTo(_CData): ...
 class _PointerLike(_CanCastTo): ...
 
 _ECT: TypeAlias = Callable[[type[_CData] | None, _FuncPointer, tuple[_CData, ...]], _CData]
-_PF: TypeAlias = _UnionT[tuple[int], tuple[int, str], tuple[int, str, Any]]
+_PF: TypeAlias = tuple[int] | tuple[int, str] | tuple[int, str, Any]
 
 class _FuncPointer(_PointerLike, _CData):
     restype: type[_CData] | Callable[[int], Any] | None

stdlib/distutils/ccompiler.pyi

@@ -1,8 +1,8 @@
 from collections.abc import Callable
-from typing import Any, Union
+from typing import Any
 from typing_extensions import TypeAlias
 
-_Macro: TypeAlias = Union[tuple[str], tuple[str, str | None]]
+_Macro: TypeAlias = tuple[str] | tuple[str, str | None]
 
 def gen_lib_options(
     compiler: CCompiler, library_dirs: list[str], runtime_library_dirs: list[str], libraries: list[str]

stdlib/email/__init__.pyi

@@ -1,12 +1,12 @@
 from collections.abc import Callable
 from email.message import Message
 from email.policy import Policy
-from typing import IO, Union
+from typing import IO
 from typing_extensions import TypeAlias
 
 # Definitions imported by multiple submodules in typeshed
-_ParamType: TypeAlias = Union[str, tuple[str | None, str | None, str]]  # noqa: Y047
-_ParamsType: TypeAlias = Union[str, None, tuple[str, str | None, str]]  # noqa: Y047
+_ParamType: TypeAlias = str | tuple[str | None, str | None, str]  # noqa: Y047
+_ParamsType: TypeAlias = str | None | tuple[str, str | None, str]  # noqa: Y047
 
 def message_from_string(s: str, _class: Callable[[], Message] = ..., *, policy: Policy = ...) -> Message: ...
 def message_from_bytes(s: bytes | bytearray, _class: Callable[[], Message] = ..., *, policy: Policy = ...) -> Message: ...

stdlib/inspect.pyi

@@ -25,7 +25,7 @@ from types import (
     TracebackType,
     WrapperDescriptorType,
 )
-from typing import Any, ClassVar, NamedTuple, Protocol, TypeVar, Union, overload
+from typing import Any, ClassVar, NamedTuple, Protocol, TypeVar, overload
 from typing_extensions import Literal, ParamSpec, TypeAlias, TypeGuard
 
 if sys.version_info >= (3, 11):
@@ -264,9 +264,9 @@ def isdatadescriptor(object: object) -> TypeGuard[_SupportsSet[Any, Any] | _Supp
 #
 # Retrieving source code
 #
-_SourceObjectType: TypeAlias = Union[
-    ModuleType, type[Any], MethodType, FunctionType, TracebackType, FrameType, CodeType, Callable[..., Any]
-]
+_SourceObjectType: TypeAlias = (
+    ModuleType | type[Any] | MethodType | FunctionType | TracebackType | FrameType | CodeType | Callable[..., Any]
+)
 
 def findsource(object: _SourceObjectType) -> tuple[list[str], int]: ...
 def getabsfile(object: _SourceObjectType, _filename: str | None = None) -> str: ...

stdlib/logging/__init__.pyi

@@ -7,7 +7,7 @@ from re import Pattern
 from string import Template
 from time import struct_time
 from types import FrameType, TracebackType
-from typing import Any, ClassVar, Generic, TextIO, TypeVar, Union, overload
+from typing import Any, ClassVar, Generic, TextIO, TypeVar, overload
 from typing_extensions import Literal, TypeAlias
 
 if sys.version_info >= (3, 11):
@@ -61,7 +61,7 @@ __all__ = [
 if sys.version_info >= (3, 11):
     __all__ += ["getLevelNamesMapping"]
 
-_SysExcInfoType: TypeAlias = Union[tuple[type[BaseException], BaseException, TracebackType | None], tuple[None, None, None]]
+_SysExcInfoType: TypeAlias = tuple[type[BaseException], BaseException, TracebackType | None] | tuple[None, None, None]
 _ExcInfoType: TypeAlias = None | bool | _SysExcInfoType | BaseException
 _ArgsType: TypeAlias = tuple[object, ...] | Mapping[str, object]
 _FilterType: TypeAlias = Filter | Callable[[LogRecord], bool]

stdlib/marshal.pyi

@@ -1,31 +1,31 @@
 import builtins
 import types
 from _typeshed import ReadableBuffer, SupportsRead, SupportsWrite
-from typing import Any, Union
+from typing import Any
 from typing_extensions import TypeAlias
 
 version: int
 
-_Marshallable: TypeAlias = Union[
+_Marshallable: TypeAlias = (
     # handled in w_object() in marshal.c
-    None,
-    type[StopIteration],
-    builtins.ellipsis,
-    bool,
+    None
+    | type[StopIteration]
+    | builtins.ellipsis
+    | bool
     # handled in w_complex_object() in marshal.c
-    int,
-    float,
-    complex,
-    bytes,
-    str,
-    tuple[_Marshallable, ...],
-    list[Any],
-    dict[Any, Any],
-    set[Any],
-    frozenset[_Marshallable],
-    types.CodeType,
-    ReadableBuffer,
-]
+    | int
+    | float
+    | complex
+    | bytes
+    | str
+    | tuple[_Marshallable, ...]
+    | list[Any]
+    | dict[Any, Any]
+    | set[Any]
+    | frozenset[_Marshallable]
+    | types.CodeType
+    | ReadableBuffer
+)
 
 def dump(__value: _Marshallable, __file: SupportsWrite[bytes], __version: int = 4) -> None: ...
 def load(__file: SupportsRead[bytes]) -> Any: ...

stdlib/multiprocessing/connection.pyi

@@ -3,13 +3,13 @@ import sys
 import types
 from _typeshed import ReadableBuffer, Self
 from collections.abc import Iterable
-from typing import Any, Union
+from typing import Any
 from typing_extensions import SupportsIndex, TypeAlias
 
 __all__ = ["Client", "Listener", "Pipe", "wait"]
 
 # https://docs.python.org/3/library/multiprocessing.html#address-formats
-_Address: TypeAlias = Union[str, tuple[str, int]]
+_Address: TypeAlias = str | tuple[str, int]
 
 class _ConnectionBase:
     def __init__(self, handle: SupportsIndex, readable: bool = True, writable: bool = True) -> None: ...

stdlib/multiprocessing/dummy/connection.pyi

@@ -1,14 +1,14 @@
 from _typeshed import Self
 from queue import Queue
 from types import TracebackType
-from typing import Any, Union
+from typing import Any
 from typing_extensions import TypeAlias
 
 __all__ = ["Client", "Listener", "Pipe"]
 
 families: list[None]
 
-_Address: TypeAlias = Union[str, tuple[str, int]]
+_Address: TypeAlias = str | tuple[str, int]
 
 class Connection:
     _in: Any

stdlib/pickle.pyi

@@ -1,7 +1,7 @@
 import sys
 from _typeshed import ReadableBuffer, SupportsWrite
 from collections.abc import Callable, Iterable, Iterator, Mapping
-from typing import Any, ClassVar, Protocol, SupportsBytes, Union
+from typing import Any, ClassVar, Protocol, SupportsBytes
 from typing_extensions import SupportsIndex, TypeAlias, final
 
 __all__ = [
@@ -142,13 +142,13 @@ class PickleError(Exception): ...
 class PicklingError(PickleError): ...
 class UnpicklingError(PickleError): ...
 
-_ReducedType: TypeAlias = Union[
-    str,
-    tuple[Callable[..., Any], tuple[Any, ...]],
-    tuple[Callable[..., Any], tuple[Any, ...], Any],
-    tuple[Callable[..., Any], tuple[Any, ...], Any, Iterator[Any] | None],
-    tuple[Callable[..., Any], tuple[Any, ...], Any, Iterator[Any] | None, Iterator[Any] | None],
-]
+_ReducedType: TypeAlias = (
+    str
+    | tuple[Callable[..., Any], tuple[Any, ...]]
+    | tuple[Callable[..., Any], tuple[Any, ...], Any]
+    | tuple[Callable[..., Any], tuple[Any, ...], Any, Iterator[Any] | None]
+    | tuple[Callable[..., Any], tuple[Any, ...], Any, Iterator[Any] | None, Iterator[Any] | None]
+)
 
 class Pickler:
     fast: bool

stdlib/signal.pyi

@@ -3,7 +3,7 @@ from _typeshed import structseq
 from collections.abc import Callable, Iterable
 from enum import IntEnum
 from types import FrameType
-from typing import Any, Union
+from typing import Any
 from typing_extensions import Final, Never, TypeAlias, final
 
 NSIG: int
@@ -62,7 +62,7 @@ SIG_DFL: Handlers
 SIG_IGN: Handlers
 
 _SIGNUM: TypeAlias = int | Signals
-_HANDLER: TypeAlias = Union[Callable[[int, FrameType | None], Any], int, Handlers, None]
+_HANDLER: TypeAlias = Callable[[int, FrameType | None], Any] | int | Handlers | None
 
 def default_int_handler(__signalnum: int, __frame: FrameType | None) -> Never: ...
 

stdlib/socketserver.pyi

@@ -4,7 +4,7 @@ from _socket import _Address, _RetAddress
 from _typeshed import ReadableBuffer, Self
 from collections.abc import Callable
 from socket import socket as _socket
-from typing import Any, BinaryIO, ClassVar, Union
+from typing import Any, BinaryIO, ClassVar
 from typing_extensions import TypeAlias
 
 __all__ = [
@@ -29,7 +29,7 @@ if sys.platform != "win32":
         "UnixStreamServer",
     ]
 
-_RequestType: TypeAlias = Union[_socket, tuple[bytes, _socket]]
+_RequestType: TypeAlias = _socket | tuple[bytes, _socket]
 _AfUnixAddress: TypeAlias = str | ReadableBuffer  # adddress acceptable for an AF_UNIX socket
 _AfInetAddress: TypeAlias = tuple[str | bytes | bytearray, int]  # address acceptable for an AF_INET socket
 

stdlib/ssl.pyi

@@ -3,15 +3,15 @@ import socket
 import sys
 from _typeshed import ReadableBuffer, Self, StrOrBytesPath, WriteableBuffer
 from collections.abc import Callable, Iterable
-from typing import Any, NamedTuple, Union, overload
+from typing import Any, NamedTuple, overload
 from typing_extensions import Literal, TypeAlias, TypedDict, final
 
 _PCTRTT: TypeAlias = tuple[tuple[str, str], ...]
 _PCTRTTT: TypeAlias = tuple[_PCTRTT, ...]
 _PeerCertRetDictType: TypeAlias = dict[str, str | _PCTRTTT | _PCTRTT]
 _PeerCertRetType: TypeAlias = _PeerCertRetDictType | bytes | None
 _EnumRetType: TypeAlias = list[tuple[bytes, str, set[str] | bool]]
-_PasswordType: TypeAlias = Union[Callable[[], str | bytes | bytearray], str, bytes, bytearray]
+_PasswordType: TypeAlias = Callable[[], str | bytes | bytearray] | str | bytes | bytearray
 
 _SrvnmeCbType: TypeAlias = Callable[[SSLSocket | SSLObject, str | None, SSLSocket], int | None]
 

stdlib/tkinter/__init__.pyi

@@ -6,7 +6,7 @@ from enum import Enum
 from tkinter.constants import *
 from tkinter.font import _FontDescription
 from types import TracebackType
-from typing import Any, Generic, NamedTuple, Protocol, TypeVar, Union, overload
+from typing import Any, Generic, NamedTuple, Protocol, TypeVar, overload
 from typing_extensions import Literal, TypeAlias, TypedDict
 
 if sys.version_info >= (3, 9):
@@ -179,7 +179,7 @@ _CanvasItemId: TypeAlias = int
 _Color: TypeAlias = str  # typically '#rrggbb', '#rgb' or color names.
 _Compound: TypeAlias = Literal["top", "left", "center", "right", "bottom", "none"]  # -compound in manual page named 'options'
 # manual page: Tk_GetCursor
-_Cursor: TypeAlias = Union[str, tuple[str], tuple[str, str], tuple[str, str, str], tuple[str, str, str, str]]
+_Cursor: TypeAlias = str | tuple[str] | tuple[str, str] | tuple[str, str, str] | tuple[str, str, str, str]
 # example when it's sequence:  entry['invalidcommand'] = [entry.register(print), '%P']
 _EntryValidateCommand: TypeAlias = str | list[str] | tuple[str, ...] | Callable[[], bool]
 _GridIndex: TypeAlias = int | str
@@ -188,7 +188,7 @@ _Relief: TypeAlias = Literal["raised", "sunken", "flat", "ridge", "solid", "groo
 _ScreenUnits: TypeAlias = str | float  # Often the right type instead of int. Manual page: Tk_GetPixels
 # -xscrollcommand and -yscrollcommand in 'options' manual page
 _XYScrollCommand: TypeAlias = str | Callable[[float, float], object]
-_TakeFocusValue: TypeAlias = Union[int, Literal[""], Callable[[str], bool | None]]  # -takefocus in manual page named 'options'
+_TakeFocusValue: TypeAlias = int | Literal[""] | Callable[[str], bool | None]  # -takefocus in manual page named 'options'
 
 if sys.version_info >= (3, 11):
     class _VersionInfoType(NamedTuple):

stdlib/tkinter/ttk.pyi

@@ -4,7 +4,7 @@ import tkinter
 from _typeshed import Incomplete
 from collections.abc import Callable
 from tkinter.font import _FontDescription
-from typing import Any, Union, overload
+from typing import Any, overload
 from typing_extensions import Literal, TypeAlias, TypedDict
 
 __all__ = [
@@ -38,13 +38,13 @@ __all__ = [
 def tclobjs_to_py(adict: dict[Any, Any]) -> dict[Any, Any]: ...
 def setup_master(master: Incomplete | None = None): ...
 
-_Padding: TypeAlias = Union[
-    tkinter._ScreenUnits,
-    tuple[tkinter._ScreenUnits],
-    tuple[tkinter._ScreenUnits, tkinter._ScreenUnits],
-    tuple[tkinter._ScreenUnits, tkinter._ScreenUnits, tkinter._ScreenUnits],
-    tuple[tkinter._ScreenUnits, tkinter._ScreenUnits, tkinter._ScreenUnits, tkinter._ScreenUnits],
-]
+_Padding: TypeAlias = (
+    tkinter._ScreenUnits
+    | tuple[tkinter._ScreenUnits]
+    | tuple[tkinter._ScreenUnits, tkinter._ScreenUnits]
+    | tuple[tkinter._ScreenUnits, tkinter._ScreenUnits, tkinter._ScreenUnits]
+    | tuple[tkinter._ScreenUnits, tkinter._ScreenUnits, tkinter._ScreenUnits, tkinter._ScreenUnits]
+)
 
 # from ttk_widget (aka ttk::widget) manual page, differs from tkinter._Compound
 _TtkCompound: TypeAlias = Literal["text", "image", tkinter._Compound]