exit() builtin has return type NoneType, but should have return type NoReturn

[wyattscarpenter]

I have this function

from typing import NoReturn
def example() -> NoReturn:
  exit()

pytype gives me this error:

bad return type [bad-return-type]
           Expected: Never
  Actually returned: None

I think this is because https://github.com/google/pytype/blob/main/pytype/stubs/builtins/builtins.pytd#L84 lists the return type of exit as NoneType instead of NoReturn. This also affects quit.

Indeed, reveal_type(exit) is Callable[[Any], None], and if instead I define a new function, example2, that raises an exception and is declared to return NoReturn, then pytype deduces correctly that there is no error when I call that from example instead of calling example from exit.

For further context see also https://github.com/google/pytype/blob/main/pytype/stubs/builtins/typing.pytd#L412 where the NoReturn is set to nothing, not NoneType or None.

You can also see that in typeshed, they've decided the type of exit (and also quit) should be (code: sys._ExitCode = None) -> NoReturn https://github.com/python/typeshed/blob/main/stdlib/builtins.pyi#L1336