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"Cannot determine type" on inner class inheritance #5914
Description
I run mypy on the following code, with no arguments other than the file name:
class InnerBase:
pass
class OuterBase:
class Inner(InnerBase):
pass
class OuterMixin:
class Inner(InnerBase):
pass
class Outer(OuterBase, OuterMixin):
passThe output that I get is as follows:
inner.py:12: error: Cannot determine type of 'Inner' in base class 'OuterBase'
inner.py:12: error: Cannot determine type of 'Inner' in base class 'OuterMixin'
Line 12 is the line that starts with class Outer.
I don't understand why the types cannot be determined: Type[OuterBase.Inner] and Type[OuterMixin.Inner] respectively would be the types for the inner classes, I think.
Note that the errors go away when Outer inherits only from OuterBase or only from OuterMixin.
I'm using mypy 0.641 on Python 3.6.5.
Activity
ilevkivskyi commentedon Nov 19, 2018
Duplicate of #2871
(As a side note this is still technically not type safe, this is like you would a have multiple inheritance with
inner: strandinner: intin two bases.)mthuurne commentedon Nov 19, 2018
Sorry for opening a duplicate; neither the manual search I did nor the GitHub "related issues" beta function turned up the existing report.
This minimal test case leaves out some details that the production code uses. Even so, I think it's type-safe as long as the
Outerclass will only useInneraccording to theInnerBaseinterface.