Copy typechecker-internal symbols to _typeshed._type_checker_internals (#13816)

stdlib/typing.pyi

@@ -220,6 +220,7 @@ class TypeVar:
         def evaluate_default(self) -> EvaluateFunc | None: ...
 
 # Used for an undocumented mypy feature. Does not exist at runtime.
+# Obsolete, use _typeshed._type_checker_internals.promote instead.
 _promote = object()
 
 # N.B. Keep this definition in sync with typing_extensions._SpecialForm
@@ -564,6 +565,7 @@ class Coroutine(Awaitable[_ReturnT_nd_co], Generic[_YieldT_co, _SendT_nd_contra,
 
 # NOTE: This type does not exist in typing.py or PEP 484 but mypy needs it to exist.
 # The parameters correspond to Generator, but the 4th is the original type.
+# Obsolete, use _typeshed._type_checker_internals.AwaitableGenerator instead.
 @type_check_only
 class AwaitableGenerator(
     Awaitable[_ReturnT_nd_co],
@@ -946,6 +948,7 @@ if sys.version_info >= (3, 11):
 
 # Type constructors
 
+# Obsolete, will be changed to a function. Use _typeshed._type_checker_internals.NamedTupleFallback instead.
 class NamedTuple(tuple[Any, ...]):
     _field_defaults: ClassVar[dict[str, Any]]
     _fields: ClassVar[tuple[str, ...]]
@@ -970,6 +973,7 @@ class NamedTuple(tuple[Any, ...]):
 
 # Internal mypy fallback type for all typed dicts (does not exist at runtime)
 # N.B. Keep this mostly in sync with typing_extensions._TypedDict/mypy_extensions._TypedDict
+# Obsolete, use _typeshed._type_checker_internals.TypedDictFallback instead.
 @type_check_only
 class _TypedDict(Mapping[str, object], metaclass=ABCMeta):
     __total__: ClassVar[bool]