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(馃悶) false negative with dataclass "non-default argument follows default argument"聽#12137
Description
from dataclasses import dataclass
@dataclass
class A:
a: int = 0
@dataclass
class B(A):
a: int
b: strMypy shows no error but this fails at runtime with TypeError: non-default argument 'b' follows default argument
Activity
erictraut commentedon Feb 7, 2022
I don't see anywhere that this behavior is documented, but the runtime logic is clearly inheriting the default value from the base class even thought the child class doesn't provide a default value. This check was also missing in pyright, so I just added it.
sobolevn commentedon Feb 10, 2022
Funny thing, this code works correctly:
But,
mypyis confused aboutaredefinition in OP's example.noooonee commentedon Nov 21, 2024
I happened saw a similar question, can this answer fix your issue?
https://stackoverflow.com/a/69822584/1227329
JonasFiechter commentedon Jul 10, 2025
Hello @noooonee. Adding
(kw_only=True)into the decorator function Works for me, thanks