Add NoReturn (#811)

* Add NoReturn

stdlib/2/__builtin__.pyi

@@ -11,6 +11,7 @@ from typing import (
     MutableSet, ItemsView, KeysView, ValuesView, Optional, Container,
 )
 from abc import abstractmethod, ABCMeta
+from mypy_extensions import NoReturn
 
 _T = TypeVar('_T')
 _T_co = TypeVar('_T_co', covariant=True)
@@ -682,7 +683,7 @@ def dir(o: object = ...) -> List[str]: ...
 def divmod(a: int, b: int) -> Tuple[int, int]: ...
 @overload
 def divmod(a: float, b: float) -> Tuple[float, float]: ...
-def exit(code: int = ...) -> None: ...
+def exit(code: int = ...) -> NoReturn: ...
 @overload
 def filter(function: Callable[[_T], Any],
            iterable: Iterable[_T]) -> List[_T]: ...

stdlib/2/os/__init__.pyi

@@ -5,6 +5,7 @@ from typing import (
     Dict, MutableMapping, NamedTuple, overload
 )
 from . import path
+from mypy_extensions import NoReturn
 
 error = OSError
 name = ...  # type: str
@@ -185,7 +186,7 @@ def execvpe(file: AnyStr, args: Union[Tuple[AnyStr], List[AnyStr]], env: Mapping
 def execv(path: AnyStr, args: Union[Tuple[AnyStr], List[AnyStr]]) -> None: ...
 def execve(path: AnyStr, args: Union[Tuple[AnyStr], List[AnyStr]], env: Mapping[AnyStr, AnyStr]) -> None: ...
 
-def _exit(n: int) -> None: ...
+def _exit(n: int) -> NoReturn: ...
 
 def fork() -> int: ...
 def forkpty() -> Tuple[int, int]: ...

stdlib/2/sys.pyi

@@ -5,6 +5,7 @@ from typing import (
     overload, Type,
 )
 from types import FrameType, ModuleType, TracebackType, ClassType
+from mypy_extensions import NoReturn
 
 class _flags:
     bytes_warning = ...  # type: int
@@ -118,7 +119,7 @@ def exc_info() -> Tuple[Optional[Type[BaseException]],
                         Optional[TracebackType]]: ...
 
 # sys.exit() accepts an optional argument of anything printable
-def exit(arg: Any = ...) -> None:
+def exit(arg: Any = ...) -> NoReturn:
     raise SystemExit()
 def getcheckinterval() -> int: ...  # deprecated
 def getdefaultencoding() -> str: ...

stdlib/3/builtins.pyi

@@ -10,6 +10,7 @@ from typing import (
 from abc import abstractmethod, ABCMeta
 from types import TracebackType
 import sys
+from mypy_extensions import NoReturn
 
 # Note that names imported above are not automatically made visible via the
 # implicit builtins import.
@@ -697,7 +698,7 @@ def eval(source: str, globals: Dict[str, Any] = None,
          locals: Mapping[str, Any] = None) -> Any: ...  # TODO code object as source
 def exec(object: str, globals: Dict[str, Any] = None,
          locals: Mapping[str, Any] = None) -> Any: ...  # TODO code object as source
-def exit(code: int = None) -> None: ...
+def exit(code: int = None) -> NoReturn: ...
 @overload
 def filter(function: Callable[[_T], Any], iterable: Iterable[_T]) -> Iterator[_T]: ...
 @overload

stdlib/3/os/__init__.pyi

@@ -11,6 +11,7 @@ from typing import (
     Optional, Generic, Set, Callable
 )
 from . import path
+from mypy_extensions import NoReturn
 
 # ----- os variables -----
 
@@ -314,7 +315,7 @@ def execve(path: AnyStr, args: Union[Tuple[AnyStr], List[AnyStr]], env: Mapping[
 def execvp(file: AnyStr, args: Union[Tuple[AnyStr], List[AnyStr]]) -> None: ...
 def execvpe(file: AnyStr, args: Union[Tuple[AnyStr], List[AnyStr]],
             env: Mapping[str, str]) -> None: ...
-def _exit(n: int) -> None: ...
+def _exit(n: int) -> NoReturn: ...
 def fork() -> int: ...  # Unix only
 def forkpty() -> Tuple[int, int]: ...  # some flavors of Unix
 def kill(pid: int, sig: int) -> None: ...

stdlib/3/sys.pyi

@@ -8,6 +8,7 @@ from typing import (
     TypeVar, Callable, Type,
 )
 from types import TracebackType
+from mypy_extensions import NoReturn
 
 _T = TypeVar('_T')
 
@@ -120,7 +121,7 @@ def exc_info() -> Tuple[Optional[Type[BaseException]],
                         Optional[BaseException],
                         Optional[TracebackType]]: ...
 # sys.exit() accepts an optional argument of anything printable
-def exit(arg: Any = ...) -> None:
+def exit(arg: Any = ...) -> NoReturn:
     raise SystemExit()
 def getcheckinterval() -> int: ...  # deprecated
 def getdefaultencoding() -> str: ...

third_party/2/six/__init__.pyi

@@ -9,6 +9,7 @@ from typing import (
 )
 import typing
 import unittest
+from mypy_extensions import NoReturn
 
 # Exports
 from __builtin__ import unichr as unichr
@@ -79,7 +80,7 @@ def assertRaisesRegex(self: unittest.TestCase, msg: str = ...) -> Any: ...
 def assertRaisesRegex(self: unittest.TestCase, callable_obj: Callable[..., Any], *args: Any, **kwargs: Any) -> Any: ...
 def assertRegex(self: unittest.TestCase, text: AnyStr, expected_regex: Union[AnyStr, Pattern[AnyStr]], msg: str = ...) -> None: ...
 
-def reraise(tp: Optional[Type[BaseException]], value: Optional[BaseException], tb: Optional[types.TracebackType] = ...) -> None: ...
+def reraise(tp: Optional[Type[BaseException]], value: Optional[BaseException], tb: Optional[types.TracebackType] = ...) -> NoReturn: ...
 def exec_(_code_: Union[unicode, types.CodeType], _globs_: Dict[str, Any] = ..., _locs_: Dict[str, Any] = ...): ...
 def raise_from(value: BaseException, from_value: BaseException) -> None: ...
 

third_party/2and3/mypy_extensions.pyi

@@ -1,6 +1,11 @@
-from typing import Dict, Type, TypeVar
+from typing import Dict, Type, TypeVar, Union
 
 T = TypeVar('T')
 
 
 def TypedDict(typename: str, fields: Dict[str, Type[T]]) -> Type[dict]: ...
+
+# Return type that indicates a function does not return.
+# This type is equivalent to the None type, but the no-op Union is necessary to
+# distinguish the None type from the None value.
+NoReturn = Union[None]

third_party/3/six/__init__.pyi

@@ -23,6 +23,7 @@ from typing import (
 import types
 import typing
 import unittest
+from mypy_extensions import NoReturn
 
 # Exports
 from io import StringIO as StringIO, BytesIO as BytesIO
@@ -92,7 +93,7 @@ def assertRegex(self: unittest.TestCase, text: AnyStr, expected_regex: Union[Any
 
 exec_ = exec
 
-def reraise(tp: Optional[Type[BaseException]], value: Optional[BaseException], tb: Optional[types.TracebackType] = None) -> None: ...
+def reraise(tp: Optional[Type[BaseException]], value: Optional[BaseException], tb: Optional[types.TracebackType] = None) -> NoReturn: ...
 def raise_from(value: BaseException, from_value: BaseException) -> None: ...
 
 print_ = print