False positive for arguments-differ when collecting all arguments

[benf-wspdigital]

The arguments-differ check will complain about this common pattern:

class Ipsum:
    def dolor(self, elit):
        pass


class LoremIpsum(Ipsum):
    def dolor(self, *args, **kwargs):
        super().dolor(*args, **kwargs)

PyLint reports:

$ python3 -m pylint --reports=n --enable=arguments-differ lorem.py 
************* Module lorem
lorem.py:7: [W0235(useless-super-delegation), LoremIpsum.dolor] Useless super delegation in method 'dolor'
lorem.py:7: [W0221(arguments-differ), LoremIpsum.dolor] Parameters differ from overridden 'dolor' method

That code should not trigger the arguments-differ check, because that pattern is explicitly just passing through the arguments to the superclass's method.

[AWhetter]

To any beginner contributors looking to fix this: arguments-differ is raised around https://github.com/PyCQA/pylint/blob/fbdf5ba095ebbbf04db12f6c3e88e21152a30507/pylint/checkers/classes.py#L1233
This will likely need a fix in _different_parameters() or _has_different_parameters() where we should add a check for *args, and **kwargs in overridden.

[kczapla]

Hi,
I made simple fix here #1674.

[GergelyKalmar]

This fix doesn't seem to work when the overridden methods have default values:

class Ipsum:
    def dolor(self, elit=None):
        pass

pylint lorem.py
...
lorem.py:7:4: W0222: Signature differs from overridden 'dolor' method (signature-differs)

Is this to be expected?

[Pierre-Sassoulas]

@GergelyKalmar I don't think the example you gave has all the code it should, we can't know what is inherited.

[GergelyKalmar]

@Pierre-Sassoulas Sorry, I meant it in the same context as the original example in the issue report, just with a default value added:

class Ipsum:
    def dolor(self, elit=None):
        pass


class LoremIpsum(Ipsum):
    def dolor(self, *args, **kwargs):
        super().dolor(*args, **kwargs)

This should fail with a signature-differs error.

[Pierre-Sassoulas]

Thank you. It seems like a bug, I think you can open a new issue with this example :)