Ordered dataclass that inherits from abstract set produces (incorrect) errors

Hi, I am running mypy 0.910 and have the following code:

from collections.abc import Set
from dataclasses import dataclass

@dataclass(order=True)
class MySet(Set):
    pass

And here are the errors it produces:

test.py: error: You may not have a custom __lt__ method when order=True
test.py: error: You may not have a custom __gt__ method when order=True
test.py: error: You may not have a custom __le__ method when order=True
test.py: error: You may not have a custom __ge__ method when order=True
test.py:5: error: Only concrete class can be given where "Type[MySet]" is expected
test.py:6: error: Argument 1 of "__lt__" is incompatible with supertype "AbstractSet"; supertype defines the argument type as "AbstractSet[Any]"
test.py:6: note: This violates the Liskov substitution principle
test.py:6: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
test.py:6: error: Argument 1 of "__gt__" is incompatible with supertype "AbstractSet"; supertype defines the argument type as "AbstractSet[Any]"
test.py:6: error: Argument 1 of "__le__" is incompatible with supertype "AbstractSet"; supertype defines the argument type as "AbstractSet[Any]"
test.py:6: error: Argument 1 of "__ge__" is incompatible with supertype "AbstractSet"; supertype defines the argument type as "AbstractSet[Any]"
Found 9 errors in 1 file (checked 1 source file)

Setting order=False gets rid of all errors except this one:

test.py:5: error: Only concrete class can be given where "Type[MySet]" is expected

It also seems to be related to Set and MutableSet from collections.abc. I don't get this behavior with Mapping for example.

Any ideas what is happening here?

Inizia eseguendo l’esempio minimo di dataclass con mypy 0.910, quindi confronta le relative diagnosi con i casi order=False e Mapping descritti nell’issue. Traccia il modo in cui i metodi astratti di Set e MutableSet interagiscono con l’ordinamento di dataclass. Il lavoro è completato quando il reproducer non produce più gli errori errati, mentre rimangono gli errori effettivi di classe astratta e di override.