Use typing_extensions.Self in the stdlib (#9694)

stdlib/email/_header_value_parser.pyi

@@ -1,11 +1,10 @@
 import sys
-from _typeshed import Self
 from collections.abc import Iterable, Iterator
 from email.errors import HeaderParseError, MessageDefect
 from email.policy import Policy
 from re import Pattern
 from typing import Any
-from typing_extensions import Final
+from typing_extensions import Final, Self
 
 WSP: Final[set[str]]
 CFWS_LEADER: Final[set[str]]
@@ -318,7 +317,7 @@ class Terminal(str):
     syntactic_break: bool
     token_type: str
     defects: list[MessageDefect]
-    def __new__(cls: type[Self], value: str, token_type: str) -> Self: ...
+    def __new__(cls, value: str, token_type: str) -> Self: ...
     def pprint(self) -> None: ...
     @property
     def all_defects(self) -> list[MessageDefect]: ...

stdlib/email/headerregistry.pyi

@@ -1,6 +1,5 @@
 import sys
 import types
-from _typeshed import Self
 from collections.abc import Iterable, Mapping
 from datetime import datetime as _datetime
 from email._header_value_parser import (
@@ -15,7 +14,7 @@ from email._header_value_parser import (
 from email.errors import MessageDefect
 from email.policy import Policy
 from typing import Any, ClassVar, Protocol
-from typing_extensions import Literal
+from typing_extensions import Literal, Self
 
 class BaseHeader(str):
     # max_count is actually more of an abstract ClassVar (not defined on the base class, but expected to be defined in subclasses)
@@ -24,7 +23,7 @@ class BaseHeader(str):
     def name(self) -> str: ...
     @property
     def defects(self) -> tuple[MessageDefect, ...]: ...
-    def __new__(cls: type[Self], name: str, value: Any) -> Self: ...
+    def __new__(cls, name: str, value: Any) -> Self: ...
     def init(self, name: str, *, parse_tree: TokenList, defects: Iterable[MessageDefect]) -> None: ...
     def fold(self, *, policy: Policy) -> str: ...
 

stdlib/email/message.pyi

@@ -1,4 +1,3 @@
-from _typeshed import Self
 from collections.abc import Generator, Iterator, Sequence
 from email import _ParamsType, _ParamType
 from email.charset import Charset
@@ -6,7 +5,7 @@ from email.contentmanager import ContentManager
 from email.errors import MessageDefect
 from email.policy import Policy
 from typing import Any, TypeVar, overload
-from typing_extensions import TypeAlias
+from typing_extensions import Self, TypeAlias
 
 __all__ = ["Message", "EmailMessage"]
 
@@ -84,7 +83,7 @@ class Message:
     def get_charsets(self, failobj: None = None) -> list[str] | None: ...
     @overload
     def get_charsets(self, failobj: _T) -> list[str] | _T: ...
-    def walk(self: Self) -> Generator[Self, None, None]: ...
+    def walk(self) -> Generator[Self, None, None]: ...
     def get_content_disposition(self) -> str | None: ...
     def as_string(self, unixfrom: bool = False, maxheaderlen: int = 0, policy: Policy | None = None) -> str: ...
     def as_bytes(self, unixfrom: bool = False, policy: Policy | None = None) -> bytes: ...