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Incompatible definition of methods reported when using multiple inheritance #9319
Description
Using mypy 0.782, errors about incompatible method redefinitions are issued -- but only if multiple inheritance is in play.
How to Reproduce
Run mypy (without any arguments) on this script:
import enum
class C:
pass
class D(C, enum.IntFlag):
passExpected behaviour
mypy should print
Success: no issues found in 1 source file
Actual behaviour
mypy prints three error messages:
mypy-error.py:6: error: Definition of "__xor__" in base class "int" is incompatible with definition in base class "Flag"
mypy-error.py:6: error: Definition of "__or__" in base class "int" is incompatible with definition in base class "Flag"
mypy-error.py:6: error: Definition of "__and__" in base class "int" is incompatible with definition in base class "Flag"
Found 3 errors in 1 file (checked 1 source file)
Comments
The error messages go away when
- Not using multiple inheritance, i.e.
class D(enum.IntFlag)instead ofclass D(C, enum.IntFlag). - Or: when using
enum.Flaginstead ofenum.IntFlag
Activity
JukkaL commentedon Sep 11, 2020
This looks like a bug in type checking classes with multiple inheritance. You can use
# type: ignoreon line 6 as a workaround for now.mypy bug workaround (python/mypy#9319)
Add-response-model (#64)
add ignore for mypy multiple inheritence bug: python/mypy#9319
adambirds commentedon Jan 30, 2023
Is this related to this issue here? Is there any idea when a proper fix will be available?
benbovy commentedon Sep 7, 2023
Is there any update on this?
Alternatively to adding
# type: ignore, another workaround is to redefine the problematic methods in the subclass with a simple call tosuper. That's not pretty either but that prevents ignoring the whole inheritance.Fix attribute type resolution with multiple inheritance (python#18415)
Add-response-model (#64)
Revert "dirty workaround for mypy 1.5 error"