Use TypeAlias for type aliases where possible, part II (#7667)

Author: AlexWaygood

stdlib/_ast.pyi

@@ -1,13 +1,13 @@
 import sys
 from typing import Any, ClassVar
-from typing_extensions import Literal
+from typing_extensions import Literal, TypeAlias
 
 PyCF_ONLY_AST: Literal[1024]
 if sys.version_info >= (3, 8):
     PyCF_TYPE_COMMENTS: Literal[4096]
     PyCF_ALLOW_TOP_LEVEL_AWAIT: Literal[8192]
 
-_identifier = str
+_identifier: TypeAlias = str
 
 class AST:
     if sys.version_info >= (3, 10):
@@ -366,10 +366,10 @@ class Attribute(expr):
     ctx: expr_context
 
 if sys.version_info >= (3, 9):
-    _SliceT = expr
+    _SliceT: TypeAlias = expr
 else:
     class slice(AST): ...
-    _SliceT = slice
+    _SliceT: TypeAlias = slice
 
 class Slice(_SliceT):
     if sys.version_info >= (3, 10):
@@ -524,7 +524,7 @@ if sys.version_info >= (3, 10):
 
     class pattern(AST): ...
     # Without the alias, Pyright complains variables named pattern are recursively defined
-    _pattern = pattern
+    _pattern: TypeAlias = pattern
 
     class match_case(AST):
         __match_args__ = ("pattern", "guard", "body")

stdlib/_socket.pyi

@@ -17,7 +17,7 @@ _CMSGArg: TypeAlias = tuple[int, int, ReadableBuffer]
 # Addresses can be either tuples of varying lengths (AF_INET, AF_INET6,
 # AF_NETLINK, AF_TIPC) or strings (AF_UNIX).
 _Address: TypeAlias = tuple[Any, ...] | str
-_RetAddress = Any
+_RetAddress: TypeAlias = Any
 # TODO Most methods allow bytes as address objects
 
 # ----- Constants -----

stdlib/asyncio/streams.pyi

@@ -120,9 +120,9 @@ else:
 
 if sys.platform != "win32":
     if sys.version_info >= (3, 7):
-        _PathType = StrPath
+        _PathType: TypeAlias = StrPath
     else:
-        _PathType = str
+        _PathType: TypeAlias = str
     if sys.version_info >= (3, 10):
         async def open_unix_connection(
             path: _PathType | None = ..., *, limit: int = ..., **kwds: Any

stdlib/cgi.pyi

@@ -1,6 +1,6 @@
 import sys
 from _typeshed import Self, SupportsGetItem, SupportsItemAccess
-from builtins import type as _type
+from builtins import list as _list, type as _type
 from collections.abc import Iterable, Iterator, Mapping
 from types import TracebackType
 from typing import IO, Any, Protocol
@@ -87,8 +87,6 @@ class MiniFieldStorage:
     value: Any
     def __init__(self, name: Any, value: Any) -> None: ...
 
-_list = list
-
 class FieldStorage:
     FieldStorageClass: _type | None
     keep_blank_values: int

stdlib/configparser.pyi

@@ -36,9 +36,9 @@ _converters: TypeAlias = dict[str, _converter]
 _T = TypeVar("_T")
 
 if sys.version_info >= (3, 7):
-    _Path = StrOrBytesPath
+    _Path: TypeAlias = StrOrBytesPath
 else:
-    _Path = StrPath
+    _Path: TypeAlias = StrPath
 
 DEFAULTSECT: Literal["DEFAULT"]
 MAX_INTERPOLATION_DEPTH: Literal[10]

stdlib/datetime.pyi

@@ -2,7 +2,7 @@ import sys
 from _typeshed import Self
 from time import struct_time
 from typing import ClassVar, NamedTuple, NoReturn, SupportsAbs, TypeVar, overload
-from typing_extensions import Literal, final
+from typing_extensions import Literal, TypeAlias, final
 
 if sys.version_info >= (3, 9):
     __all__ = ("date", "datetime", "time", "timedelta", "timezone", "tzinfo", "MINYEAR", "MAXYEAR")
@@ -19,7 +19,7 @@ class tzinfo:
     def fromutc(self, __dt: datetime) -> datetime: ...
 
 # Alias required to avoid name conflicts with date(time).tzinfo.
-_tzinfo = tzinfo
+_tzinfo: TypeAlias = tzinfo
 
 @final
 class timezone(tzinfo):
@@ -150,8 +150,8 @@ class time:
         fold: int = ...,
     ) -> Self: ...
 
-_date = date
-_time = time
+_date: TypeAlias = date
+_time: TypeAlias = time
 
 class timedelta(SupportsAbs[timedelta]):
     min: ClassVar[timedelta]

stdlib/email/message.pyi

@@ -13,7 +13,7 @@ _T = TypeVar("_T")
 
 _PayloadType: TypeAlias = list[Message] | str | bytes
 _CharsetType: TypeAlias = Charset | str | None
-_HeaderType = Any
+_HeaderType: TypeAlias = Any
 
 class Message:
     policy: Policy  # undocumented

stdlib/functools.pyi

@@ -112,7 +112,7 @@ class partial(Generic[_T]):
         def __class_getitem__(cls, item: Any) -> GenericAlias: ...
 
 # With protocols, this could change into a generic protocol that defines __get__ and returns _T
-_Descriptor = Any
+_Descriptor: TypeAlias = Any
 
 class partialmethod(Generic[_T]):
     func: Callable[..., _T] | _Descriptor

stdlib/inspect.pyi

@@ -514,7 +514,7 @@ def getcoroutinelocals(coroutine: Coroutine[Any, Any, Any]) -> dict[str, Any]: .
 
 # Create private type alias to avoid conflict with symbol of same
 # name created in Attribute class.
-_Object = object
+_Object: TypeAlias = object
 
 class Attribute(NamedTuple):
     name: str

stdlib/lib2to3/refactor.pyi

@@ -1,11 +1,12 @@
 from collections.abc import Container, Generator, Iterable, Mapping
 from logging import Logger
 from typing import Any, ClassVar, NoReturn
+from typing_extensions import TypeAlias
 
 from .pgen2.grammar import Grammar
 
-_Driver = Any  # really lib2to3.driver.Driver
-_BottomMatcher = Any  # really lib2to3.btm_matcher.BottomMatcher
+_Driver: TypeAlias = Any  # really lib2to3.driver.Driver
+_BottomMatcher: TypeAlias = Any  # really lib2to3.btm_matcher.BottomMatcher
 
 def get_all_fix_names(fixer_pkg: str, remove_prefix: bool = ...) -> list[str]: ...
 def get_fixers_from_package(pkg_name: str) -> list[str]: ...