Add @type_check_only to stub-only private classes in stdlib (#14512)

stdlib/functools.pyi

@@ -3,7 +3,7 @@ import types
 from _typeshed import SupportsAllComparisons, SupportsItems
 from collections.abc import Callable, Hashable, Iterable, Sized
 from types import GenericAlias
-from typing import Any, Final, Generic, Literal, NamedTuple, TypedDict, TypeVar, final, overload
+from typing import Any, Final, Generic, Literal, NamedTuple, TypedDict, TypeVar, final, overload, type_check_only
 from typing_extensions import ParamSpec, Self, TypeAlias
 
 __all__ = [
@@ -48,6 +48,7 @@ class _CacheInfo(NamedTuple):
     maxsize: int | None
     currsize: int
 
+@type_check_only
 class _CacheParameters(TypedDict):
     maxsize: int
     typed: bool
@@ -96,6 +97,7 @@ else:
 
 WRAPPER_UPDATES: tuple[Literal["__dict__"]]
 
+@type_check_only
 class _Wrapped(Generic[_PWrapped, _RWrapped, _PWrapper, _RWrapper]):
     __wrapped__: Callable[_PWrapped, _RWrapped]
     def __call__(self, *args: _PWrapper.args, **kwargs: _PWrapper.kwargs) -> _RWrapper: ...
@@ -103,6 +105,7 @@ class _Wrapped(Generic[_PWrapped, _RWrapped, _PWrapper, _RWrapper]):
     __name__: str
     __qualname__: str
 
+@type_check_only
 class _Wrapper(Generic[_PWrapped, _RWrapped]):
     def __call__(self, f: Callable[_PWrapper, _RWrapper]) -> _Wrapped[_PWrapped, _RWrapped, _PWrapper, _RWrapper]: ...
 
@@ -180,6 +183,7 @@ if sys.version_info >= (3, 11):
 else:
     _RegType: TypeAlias = type[Any]
 
+@type_check_only
 class _SingleDispatchCallable(Generic[_T]):
     registry: types.MappingProxyType[Any, Callable[..., _T]]
     def dispatch(self, cls: Any) -> Callable[..., _T]: ...