Use Final for Constant Literals in the stdlib (#12332)

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

stdlib/asyncio/base_futures.pyi

@@ -1,6 +1,6 @@
 from collections.abc import Callable, Sequence
 from contextvars import Context
-from typing import Any, Literal
+from typing import Any, Final
 
 from . import futures
 
@@ -11,9 +11,9 @@ __all__ = ()
 # That's why the import order is reversed.
 from .futures import isfuture as isfuture
 
-_PENDING: Literal["PENDING"]  # undocumented
-_CANCELLED: Literal["CANCELLED"]  # undocumented
-_FINISHED: Literal["FINISHED"]  # undocumented
+_PENDING: Final = "PENDING"  # undocumented
+_CANCELLED: Final = "CANCELLED"  # undocumented
+_FINISHED: Final = "FINISHED"  # undocumented
 
 def _format_callbacks(cb: Sequence[tuple[Callable[[futures.Future[Any]], None], Context]]) -> str: ...  # undocumented
 def _future_repr_info(future: futures.Future[Any]) -> list[str]: ...  # undocumented

stdlib/asyncio/constants.pyi

@@ -1,18 +1,18 @@
 import enum
 import sys
-from typing import Literal
+from typing import Final
 
-LOG_THRESHOLD_FOR_CONNLOST_WRITES: Literal[5]
-ACCEPT_RETRY_DELAY: Literal[1]
-DEBUG_STACK_DEPTH: Literal[10]
+LOG_THRESHOLD_FOR_CONNLOST_WRITES: Final = 5
+ACCEPT_RETRY_DELAY: Final = 1
+DEBUG_STACK_DEPTH: Final = 10
 SSL_HANDSHAKE_TIMEOUT: float
-SENDFILE_FALLBACK_READBUFFER_SIZE: Literal[262144]
+SENDFILE_FALLBACK_READBUFFER_SIZE: Final = 262144
 if sys.version_info >= (3, 11):
     SSL_SHUTDOWN_TIMEOUT: float
-    FLOW_CONTROL_HIGH_WATER_SSL_READ: Literal[256]
-    FLOW_CONTROL_HIGH_WATER_SSL_WRITE: Literal[512]
+    FLOW_CONTROL_HIGH_WATER_SSL_READ: Final = 256
+    FLOW_CONTROL_HIGH_WATER_SSL_WRITE: Final = 512
 if sys.version_info >= (3, 12):
-    THREAD_JOIN_TIMEOUT: Literal[300]
+    THREAD_JOIN_TIMEOUT: Final = 300
 
 class _SendfileMode(enum.Enum):
     UNSUPPORTED = 1

stdlib/asyncio/sslproto.pyi

@@ -3,7 +3,7 @@ import sys
 from collections import deque
 from collections.abc import Callable
 from enum import Enum
-from typing import Any, ClassVar, Literal
+from typing import Any, ClassVar, Final, Literal
 from typing_extensions import TypeAlias
 
 from . import constants, events, futures, protocols, transports
@@ -29,10 +29,10 @@ if sys.version_info >= (3, 11):
     def add_flowcontrol_defaults(high: int | None, low: int | None, kb: int) -> tuple[int, int]: ...
 
 else:
-    _UNWRAPPED: Literal["UNWRAPPED"]
-    _DO_HANDSHAKE: Literal["DO_HANDSHAKE"]
-    _WRAPPED: Literal["WRAPPED"]
-    _SHUTDOWN: Literal["SHUTDOWN"]
+    _UNWRAPPED: Final = "UNWRAPPED"
+    _DO_HANDSHAKE: Final = "DO_HANDSHAKE"
+    _WRAPPED: Final = "WRAPPED"
+    _SHUTDOWN: Final = "SHUTDOWN"
 
 if sys.version_info < (3, 11):
     class _SSLPipe:

stdlib/asyncio/windows_events.pyi

@@ -2,7 +2,7 @@ import socket
 import sys
 from _typeshed import Incomplete, ReadableBuffer, WriteableBuffer
 from collections.abc import Callable
-from typing import IO, Any, ClassVar, Literal, NoReturn
+from typing import IO, Any, ClassVar, Final, NoReturn
 
 from . import events, futures, proactor_events, selector_events, streams, windows_utils
 
@@ -28,10 +28,10 @@ if sys.platform == "win32":
             "WindowsProactorEventLoopPolicy",
         )
 
-    NULL: Literal[0]
-    INFINITE: Literal[0xFFFFFFFF]
-    ERROR_CONNECTION_REFUSED: Literal[1225]
-    ERROR_CONNECTION_ABORTED: Literal[1236]
+    NULL: Final = 0
+    INFINITE: Final = 0xFFFFFFFF
+    ERROR_CONNECTION_REFUSED: Final = 1225
+    ERROR_CONNECTION_ABORTED: Final = 1236
     CONNECT_PIPE_INIT_DELAY: float
     CONNECT_PIPE_MAX_DELAY: float
 

stdlib/asyncio/windows_utils.pyi

@@ -2,13 +2,13 @@ import subprocess
 import sys
 from collections.abc import Callable
 from types import TracebackType
-from typing import Any, AnyStr, Literal
+from typing import Any, AnyStr, Final
 from typing_extensions import Self
 
 if sys.platform == "win32":
     __all__ = ("pipe", "Popen", "PIPE", "PipeHandle")
 
-    BUFSIZE: Literal[8192]
+    BUFSIZE: Final = 8192
     PIPE = subprocess.PIPE
     STDOUT = subprocess.STDOUT
     def pipe(*, duplex: bool = False, overlapped: tuple[bool, bool] = (True, True), bufsize: int = 8192) -> tuple[int, int]: ...