Relax union math logic to allow signatures with different arg kinds #5222
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Resolves python#5204. This commit relaxes the union math logic so that it allows signatures with arg kinds that are nearly identical except that one arg is positional and the other is optional. This commit also removes the "names must be the same" restriction mostly so that the original example given in python#4576 will pass. (In retrospect, I think this check didn't really buy us much -- even if the alternatives share the same arg names, there's no guarantee the actual implementation signature will also share the same.)
ilevkivskyi
approved these changes
Jun 15, 2018
| reveal_type(f(A())) # E: Revealed type is '__main__.B' | ||
| reveal_type(f(B())) # E: Revealed type is '__main__.C' | ||
| f(x) # E: Argument 1 to "f" has incompatible type "Union[A, B]"; expected "A" | ||
| reveal_type(f(x)) # E: Revealed type is 'Union[__main__.B, __main__.C]' |
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The test case name should be updated (remove "Skip").
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| x: Union[A, B] | ||
| f(x) # E: Argument 1 to "f" has incompatible type "Union[A, B]"; expected "A" | ||
| f(x, B()) # E: Argument 1 to "f" has incompatible type "Union[A, B]"; expected "B" |
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I think ideally we could support something like this. Could you please add a TODO here? (I see you have a TODO in code, but I would prefer to have them both).
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Thanks! Merging now. |
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Resolves #5204.
This commit relaxes the union math logic so that it allows signatures with arg kinds that are nearly identical except that one arg is positional and the other is optional.
This commit also removes the "names must be the same" restriction mostly so that the original example given in #4576 will pass. (In retrospect, I think this check didn't really buy us much -- even if the alternatives share the same arg names, there's no guarantee the actual implementation signature will also share the same.)