unexpected-keyword-arg in dataclasses with kw_only=True, inheritance and defaults

[sharhalakis]

Bug description

This is practically #6275 when using the new kw_only=True

The following code causes the bogus error. The key points are:

• the kw_only argument on class A
• the presence of a default in class A
• that class B includes a value without a default.

The problem doesn't happen if there's no default in-between or if inheritance isn't used.

# pylint: disable=missing-module-docstring,invalid-name,too-few-public-methods,missing-class-docstring

import dataclasses as dc

@dc.dataclass(kw_only=True)
class A:
    a: str
    b: int = 1

@dc.dataclass(kw_only=True)
class B(A):
    c: str

c = B(a='aaa', c='ccc')

Command used

pylint b.py

Pylint output

$ pylint b.py 
************* Module b
b.py:15:4: E1123: Unexpected keyword argument 'c' in constructor call (unexpected-keyword-arg)

------------------------------------------------------------------
Your code has been rated at 3.75/10 (previous run: 3.75/10, +0.00)

Expected behavior

No pylint errors. This is valid code.

Pylint version

$ pylint --version
pylint 2.12.2
astroid 2.9.3
Python 3.10.4 (main, Mar 24 2022, 13:07:27) [GCC 11.2.0]

OS / Environment

$ lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description:    Debian GNU/Linux bookworm/sid
Release:        testing
Codename:       bookworm

[anis-campos]

+1. kw_only is very useful and the completely disabling unexpected-keyword-arg seems counter productive.

So for now we are disabling the linter on every instantiation.

[smrnff]

+1 We really need the feature too.

So for now we are disabling the linter on every instantiation.

We do the same things. It freaks me out.

[DanielNoord]

Fixed with in pylint-dev/astroid#1764

@jacobtylerwalls Do we want test for this and for the original issue that that PR targeted in pylint? Or is astroid enough in your opinion?

[jacobtylerwalls]

Let's merge at least one test case in pylint, since the astroid one is a little convoluted (on purpose, to catch the string contains issue.)

[DanielNoord]

Sure! I'll open a PR for you to review 😄

[yarinbar]

I am experiencing the same issue even when i dont use default values and I even tried defining my own init function:

@dataclass(kw_only=True)
class Alert:
    """of alerts"""
    alert_type: str
    location: torch.Tensor
    # score: float = 1.

    def __init__(self, **kwargs):
        for k, v in kwargs.items():
            if k != 'self':
                setattr(self, k, v)


@dataclass(kw_only=True)
class RoofingAlert(Alert):
    # type = 'roofing'
    # location: torch.Tensor
    angle: float
    cath_direction: torch.Tensor
    vess_direction: torch.Tensor

    def __init__(self, **kwargs):
        super().__init__(alert_type=kwargs.get('alert_type'), location=kwargs.get('location'))
        for k, v in kwargs.items():
            if k != 'self':
                setattr(self, k, v)

and the error:

     80     if point_res:
     81         alerts.append(
---> 82             RoofingAlert(
     83                 alert_type='roofing',
     84                 location=torch.tensor(point),
     85                 angle=angle,
     86                 cath_direction=cath_dir,
     87                 vess_direction=vess_dir
     88             )
     89         )
     91 return alerts

TypeError: RoofingAlert.__init__() got an unexpected keyword argument 'alert_type'

[Pierre-Sassoulas]

Hello and thank you for reporting an issue @yarinbar. Could you open a new issue, this one is closed and the comment is going to get lost.