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Inconsistency in Union/promotion interactions #6168
Description
In the following test
from typing import Union
class A:
x: Union[int, float]
def foo(x: Union[int, float], y: A) -> None:
reveal_type(x)
reveal_type(y.x)
we emit:
lol.py:8: error: Revealed type is 'Union[builtins.int, builtins.float]'
lol.py:9: error: Revealed type is 'builtins.float'
That is to say, class attributes have unions simplified using promotions while arguments (and locals) do not.
Probably they ought to have the same behavior?
(And probably the behavior ought to be to not simplify, especially because of #6114)
Activity
Fix mypy_mypyc crash caused by "complex" interaction
Fix mypy_mypyc crash caused by "complex" interaction (#6169)
ilevkivskyi commentedon Jan 9, 2019
Yes, I think we should never use promotions in union simplification. Also this looks like something that may be easy to fix. We just need to use
ignore_promotions=TrueinUnionType.make_simplified_union().ilevkivskyi commentedon Jul 18, 2019
Added usability label because this can cause confusion, see #7241.
hauntsaninja commentedon Apr 26, 2023
These currently have the same type