Sync recent typing and typing_extensions updates (#3070)

This includes two things to sync up with recent runtime updates:
* Move `Final`, `@final`, `Literal`, and `TypedDict` to `typing` (`typing_extensions` still defines or re-exports them)
* Rename `@typing.runtime` to `@typing.runtime_checkable`, while keeping `@runtime` as a backwards-compatible alias in `typing_extensions`.

stdlib/2/typing.pyi

@@ -22,6 +22,12 @@ Protocol: _SpecialForm = ...
 Callable: _SpecialForm = ...
 Type: _SpecialForm = ...
 ClassVar: _SpecialForm = ...
+Final: _SpecialForm = ...
+_F = TypeVar('_F', bound=Callable[..., Any])
+def final(f: _F) -> _F: ...
+Literal: _SpecialForm = ...
+# TypedDict is a (non-subscriptable) special form.
+TypedDict: object = ...
 
 class GenericMeta(type): ...
 
@@ -65,39 +71,39 @@ _T_contra = TypeVar('_T_contra', contravariant=True)  # Ditto contravariant.
 _TC = TypeVar('_TC', bound=Type[object])
 _C = TypeVar("_C", bound=Callable)
 
-def runtime(cls: _TC) -> _TC: ...
+def runtime_checkable(cls: _TC) -> _TC: ...
 
-@runtime
+@runtime_checkable
 class SupportsInt(Protocol, metaclass=ABCMeta):
     @abstractmethod
     def __int__(self) -> int: ...
 
-@runtime
+@runtime_checkable
 class SupportsFloat(Protocol, metaclass=ABCMeta):
     @abstractmethod
     def __float__(self) -> float: ...
 
-@runtime
+@runtime_checkable
 class SupportsComplex(Protocol, metaclass=ABCMeta):
     @abstractmethod
     def __complex__(self) -> complex: ...
 
-@runtime
+@runtime_checkable
 class SupportsAbs(Protocol[_T_co]):
     @abstractmethod
     def __abs__(self) -> _T_co: ...
 
-@runtime
+@runtime_checkable
 class Reversible(Protocol[_T_co]):
     @abstractmethod
     def __reversed__(self) -> Iterator[_T_co]: ...
 
-@runtime
+@runtime_checkable
 class Sized(Protocol, metaclass=ABCMeta):
     @abstractmethod
     def __len__(self) -> int: ...
 
-@runtime
+@runtime_checkable
 class Hashable(Protocol, metaclass=ABCMeta):
     # TODO: This is special, in that a subclass of a hashable class may not be hashable
     #   (for example, list vs. object). It's not obvious how to represent this. This class
@@ -105,12 +111,12 @@ class Hashable(Protocol, metaclass=ABCMeta):
     @abstractmethod
     def __hash__(self) -> int: ...
 
-@runtime
+@runtime_checkable
 class Iterable(Protocol[_T_co]):
     @abstractmethod
     def __iter__(self) -> Iterator[_T_co]: ...
 
-@runtime
+@runtime_checkable
 class Iterator(Iterable[_T_co], Protocol[_T_co]):
     @abstractmethod
     def next(self) -> _T_co: ...
@@ -135,7 +141,7 @@ class Generator(Iterator[_T_co], Generic[_T_co, _T_contra, _V_co]):
     @property
     def gi_running(self) -> bool: ...
 
-@runtime
+@runtime_checkable
 class Container(Protocol[_T_co]):
     @abstractmethod
     def __contains__(self, x: object) -> bool: ...
@@ -234,7 +240,7 @@ class ValuesView(MappingView, Iterable[_VT_co], Generic[_VT_co]):
     def __contains__(self, o: object) -> bool: ...
     def __iter__(self) -> Iterator[_VT_co]: ...
 
-@runtime
+@runtime_checkable
 class ContextManager(Protocol[_T_co]):
     def __enter__(self) -> _T_co: ...
     def __exit__(self, __exc_type: Optional[Type[BaseException]],
@@ -462,6 +468,21 @@ class NamedTuple(tuple):
     def _asdict(self) -> dict: ...
     def _replace(self: _T, **kwargs: Any) -> _T: ...
 
+# Internal mypy fallback type for all typed dicts (does not exist at runtime)
+class _TypedDict(Mapping[str, object], metaclass=ABCMeta):
+    def copy(self: _T) -> _T: ...
+    # Using NoReturn so that only calls using mypy plugin hook that specialize the signature
+    # can go through.
+    def setdefault(self, k: NoReturn, default: object) -> object: ...
+    # Mypy plugin hook for 'pop' expects that 'default' has a type variable type.
+    def pop(self, k: NoReturn, default: _T = ...) -> object: ...
+    def update(self: _T, __m: _T) -> None: ...
+    def has_key(self, k: str) -> bool: ...
+    def viewitems(self) -> ItemsView[str, object]: ...
+    def viewkeys(self) -> KeysView[str]: ...
+    def viewvalues(self) -> ValuesView[object]: ...
+    def __delitem__(self, k: NoReturn) -> None: ...
+
 def NewType(name: str, tp: Type[_T]) -> Type[_T]: ...
 
 # This itself is only available during type checking