Use TypeAlias where possible for type aliases (#7630)

stdlib/lib2to3/pgen2/grammar.pyi

@@ -1,8 +1,9 @@
 from _typeshed import Self, StrPath
+from typing_extensions import TypeAlias
 
-_Label = tuple[int, str | None]
-_DFA = list[list[tuple[int, int]]]
-_DFAS = tuple[_DFA, dict[int, int]]
+_Label: TypeAlias = tuple[int, str | None]
+_DFA: TypeAlias = list[list[tuple[int, int]]]
+_DFAS: TypeAlias = tuple[_DFA, dict[int, int]]
 
 class Grammar:
     symbol2number: dict[str, int]

stdlib/lib2to3/pgen2/parse.pyi

@@ -1,8 +1,9 @@
 from lib2to3.pgen2.grammar import _DFAS, Grammar
 from lib2to3.pytree import _NL, _Convert, _RawNode
 from typing import Any, Sequence
+from typing_extensions import TypeAlias
 
-_Context = Sequence[Any]
+_Context: TypeAlias = Sequence[Any]
 
 class ParseError(Exception):
     msg: str

stdlib/lib2to3/pgen2/tokenize.pyi

@@ -1,6 +1,7 @@
 import sys
 from lib2to3.pgen2.token import *
 from typing import Callable, Iterable, Iterator
+from typing_extensions import TypeAlias
 
 if sys.version_info >= (3, 8):
     __all__ = [
@@ -146,9 +147,9 @@ else:
         "untokenize",
     ]
 
-_Coord = tuple[int, int]
-_TokenEater = Callable[[int, str, _Coord, _Coord, str], None]
-_TokenInfo = tuple[int, str, _Coord, _Coord, str]
+_Coord: TypeAlias = tuple[int, int]
+_TokenEater: TypeAlias = Callable[[int, str, _Coord, _Coord, str], None]
+_TokenInfo: TypeAlias = tuple[int, str, _Coord, _Coord, str]
 
 class TokenError(Exception): ...
 class StopTokenizing(Exception): ...

stdlib/lib2to3/pytree.pyi

@@ -1,12 +1,13 @@
 from _typeshed import Self
 from lib2to3.pgen2.grammar import Grammar
 from typing import Any, Callable, Iterator
+from typing_extensions import TypeAlias
 
-_NL = Node | Leaf
-_Context = tuple[str, int, int]
-_Results = dict[str, _NL]
-_RawNode = tuple[int, str, _Context, list[_NL] | None]
-_Convert = Callable[[Grammar, _RawNode], Any]
+_NL: TypeAlias = Node | Leaf
+_Context: TypeAlias = tuple[str, int, int]
+_Results: TypeAlias = dict[str, _NL]
+_RawNode: TypeAlias = tuple[int, str, _Context, list[_NL] | None]
+_Convert: TypeAlias = Callable[[Grammar, _RawNode], Any]
 
 HUGE: int