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Keep Any when restricting Union in isinstance #2446

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Merged
merged 2 commits into from
Nov 15, 2016
Merged

Keep Any when restricting Union in isinstance #2446

merged 2 commits into from
Nov 15, 2016

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ilevkivskyi
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Fixes #1720

Currently, mypy incorrectly determines restrictions of unions containing Any after isinstance(), for example:

def func(v: Union[int, Any]) -> None:
    if isinstance(v, int):
        reveal_type(s) # This is correctly int
    else:
        reveal_type(s) # But this is incorrectly Union[<ERROR>, void], should be Any

This PR fixes this by not considering Any a subtype-of-every-type when restricting the union.

(Note that this PR is not a replacement for #2197 but a complement to it.)

@gvanrossum
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Probably best for @ddfisher or @JukkaL to review.

@JukkaL
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JukkaL commented Nov 15, 2016

Looks good -- thanks!

@JukkaL JukkaL merged commit a488641 into python:master Nov 15, 2016
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Successfully merging this pull request may close these issues.

type of Union containing Any is incorrectly inferred after an isinstance check
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@ilevkivskyi @gvanrossum @JukkaL