Running mypy --strict-optional on the mypy codebase itself, we get this error:
mypy/build.py: note: In member "wrap_context" of class "State":
mypy/build.py:1170: error: Yield value expected
The function in question looks like this:
@contextlib.contextmanager
def wrap_context(self) -> Iterator[None]:
save_import_context = self.manager.errors.import_context()
self.manager.errors.set_import_context(self.import_context)
try:
yield
except CompileError:
raise
except Exception as err:
report_internal_error(err, self.path, 0)
self.manager.errors.set_import_context(save_import_context)
self.check_blockers()
This is pretty sensible idiomatic code. Arguably there might be some other appropriate annotation to write for the return type; bracketing that question, it looks to be perfectly well-typed code that shouldn't produce an error. It's also not immediately clear to me how to work around it, except I guess with a # type: ignore.
I suspect this is related to the complicated treatment we give in some places to None as a return type -- cf #1509, #299, #359 -- and that treating None in a more regular way as discussed in #1278 and #1847 would fix it.
It may also be related to #1933, but I haven't yet read through that discussion to understand what's going on there.
Running
mypy --strict-optionalon the mypy codebase itself, we get this error:The function in question looks like this:
This is pretty sensible idiomatic code. Arguably there might be some other appropriate annotation to write for the return type; bracketing that question, it looks to be perfectly well-typed code that shouldn't produce an error. It's also not immediately clear to me how to work around it, except I guess with a
# type: ignore.I suspect this is related to the complicated treatment we give in some places to None as a return type -- cf #1509, #299, #359 -- and that treating None in a more regular way as discussed in #1278 and #1847 would fix it.
It may also be related to #1933, but I haven't yet read through that discussion to understand what's going on there.