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Fix --incremental crash on Type[...] #4038

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Merged
merged 2 commits into from
Oct 11, 2017
Merged

Fix --incremental crash on Type[...] #4038

merged 2 commits into from
Oct 11, 2017

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ilevkivskyi
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@ilevkivskyi ilevkivskyi commented Sep 30, 2017 •
edited by gvanrossum
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This fixes the second traceback reported in #3852. This also improves member lookup on Type[...] by moving it to a later stage (checkmember.py instead of some manipulations in TypeType constructor that are dangerous during de-serialization).

By the way it looks like the first traceback reported in #3852 is just another manifestation of #3052, but instead of just deleting a class it is replaced by a Var or by a FunctionDef.

Also fixes #4058.

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Is this something urgent (fixing a regression in a recent change) that should be cherry-picked into the release branch? Or is this something that has been around for a long time? It seems the second crash in #3852 is related to pointing mypypath to site-packages, which is not recommended.

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Is this something urgent (fixing a regression in a recent change) that should be cherry-picked into the release branch? Or is this something that has been around for a long time?

The bug is quite old (around a year), it started to be a crash in 0.510. So I don't think it is something urgent.

It seems the second crash in #3852 is related to pointing mypypath to site-packages, which is not recommended.

The crash doesn't depend on MYPYPATH setting, but the probability to find more dynamic code in libraries is higher. For example, the crash appears on type(f) , where f is a callable other than class object.

This was referenced Oct 2, 2017
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@ilevkivskyi ilevkivskyi mentioned this pull request Oct 9, 2017
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@JukkaL JukkaL self-assigned this Oct 9, 2017
JukkaL
JukkaL reviewed Oct 10, 2017
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mypy/types.py
self.item = item.fallback
else:
self.item = item
self.item = item
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Why does this change help? Is it because the type attribute of an Instance might refer to FakeInfo during deserialization?

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Yes.

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(Or previously to None)

JukkaL
JukkaL approved these changes Oct 11, 2017
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LGTM. Thanks for the fix!

@JukkaL JukkaL merged commit bd1b3d7 into python:master Oct 11, 2017
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self.__class__.__name__ has type Any in class derived from Any
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