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Incorrect inferred type for attribute with two partial types #20257
Description
Unexpected type is inferred for attribute x in this example:
class C:
def __init__(self) -> None:
if int():
self.x = None
return
self.x = []
self.x.append("x")
reveal_type(C().x) # "list[str]" -- but should be "list[str] | None"The inferred type should be list[str] | None, or alternatively mypy could require a type annotation for x, if this is too tricky to infer.
This should be tested with and without --allow-redefinition-new, since it may make a difference.
Activity
lamia-bel commentedon Dec 8, 2025
hello , i would like to work on this issue.
Could you please confirm if this issue is still open for contributions? I would be happy to start working on it.
Thank you!