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Always complain if returning a value if annotated to return None #1509
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If you're saying that in a function declared as
-> None, any return statement with an expression should always be flagged as an error, I agree with you, though it's technically a style choice, and I've occasionally seen code that uses this knowing the function being called is also returning None, just as a shorthand forg() return
IIRC there was also some discussion with @ddfisher about the opposite -- whether in a function declared to return an Optional type, a bare
return(or falling off the end) is acceptable style or not.Added label
depends-on/strict-optionalbecause I think anything we do here will probably look different in the strict-optional world from the no-strict-optional world, and any discussion should probably be in the context of the strict-optional world which we intend to be the only world in the future.- added this to the milestone
on Aug 4, 2016 - removed this from the milestone
on Mar 29, 2017 Mypy now correctly emits an error if
--warn-return-anyand/or--strictare specified (though the default behavior is still that it emits no errors).Is this sufficient? — can this issue now be closed?
Mypy doesn't complain about this code that returns a value in a function declared to return
None, since the return value isAny:I think that mypy could complain about the return statement even if the value has type
Any. The current behavior is not inconsistent or incorrect, but probably not optimal.