Invalid behavior of ReturnValue\FunctionCall mutator with return type hint?

[lcobucci]

The Humbug\Mutator\ReturnValue\FunctionCall is replacing the return statement with a null value even when a non-nullable return type hint is set, generating a TypeError.

I believe that this mutator should be just executed when return type is not set or is nullable (PHP 7.1+), however I'm not sure how to implement that (or if you think that it should be done).

[padraic]

I'm not really sure if that's a bug though. Generating an error after a mutation is generally a Good Thing. Is there a scenario where it's not?

[lcobucci]

It might not be a bug indeed.
I agree that generating an error after a mutation is a good thing but should it be presented together with the "bad things"?

(btw good to see you back here 😉 )

[padraic]

@lcobucci With a bit more time to recover from being on vacation (my brain may have wanted to stay there ;)), the proper response to this issue should have been that while this is not a bug, it is an omitted feature. Operating under PHP 7, we should be mutating the return value based on the return type hint, so it’s a definite enhancement for Humbug 2.0. This would only apply where we know the return type, or can infer it, otherwise NULL would be the default. The mutation return value would follow the rules for explicit values of the same type, already implemented (e.g. flipping Booleans).