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Issues with enum indexing #1464
Description
I encountered some issues with indexing on enum classes that use multiple inheritance. I'm using the following test script:
from enum import Enum
from typing import TYPE_CHECKING
if not TYPE_CHECKING:
reveal_type = print
class I(int, Enum):
a = 1
reveal_type(I['a']) # E: Revealed type is '__main__.I'
class S(str, Enum):
a = '1'
reveal_type(S['a']) # E: Revealed type is '__main__.S'
class F(float, Enum):
a = 1.0
reveal_type(F['a']) # E: Revealed type is '__main__.F'All of this works at runtime; it prints I.a, S.a, F.a.
With current mypy master (incorporating most recent typeshed changes) I get:
$ mypy bin/enumindex.py
bin/enumindex.py:7: error: Definition of "__new__" in base class "int" is incompatible with definition in base class "Enum"
bin/enumindex.py:9: error: Revealed type is 'Any'
bin/enumindex.py:9: error: Value of type Type[I] is not indexable
bin/enumindex.py:11: error: Definition of "__new__" in base class "str" is incompatible with definition in base class "Enum"
bin/enumindex.py:13: error: Revealed type is 'Any'
bin/enumindex.py:13: error: Value of type Type[S] is not indexable
bin/enumindex.py:17: error: Revealed type is 'enumindex.F'
With the most recent mypy release it's better:
$ mypy bin/enumindex.py
bin/enumindex.py:9: error: Revealed type is 'enumindex.I'
bin/enumindex.py:13: error: Revealed type is 'Any'
bin/enumindex.py:13: error: Value of type "S" is not indexable
bin/enumindex.py:17: error: Revealed type is 'enumindex.F'
So there's a regression, which is caused by #1352 (cc @sproshev). Perhaps we should revert that PR? It fixed a relatively obscure case, and multiple inheritance from Enum is explicitly mentioned in the docs (https://docs.python.org/3/library/enum.html#others).
But the previous behavior was buggy too: somehow indexing worked on multiple inheritance from float or int, but not str. I'm not sure how to explain that yet. It doesn't reproduce in a mypy test, so presumably it's due to something in the typeshed stubs.
Activity
gvanrossum commentedon Jul 4, 2017
I never did like #1352 much, so fine to revert if there's nothing better.