Pylint: Unused arguments not reported in classes

[GergelyKalmar]

Steps to reproduce

Create a class as follows:

class Test:
    def __init__(self, test_arg):
        pass

and run pylint against it.

Current behavior

Pylint does not report 'unused-argument' on class methods.

Expected behavior

Pylint does report 'unused-argument' on class methods.

pylint --version output

pylint 2.4.4
astroid 2.3.3
Python 3.5.2 (default, Oct 8 2019, 13:06:37)
[GCC 5.4.0 20160609]

[PCManticore]

Thanks for the report!

[GergelyKalmar]

Any news on this one? Was someone able to reproduce or is the problem with my setup somehow?

[brycepg]

pylint writes this method off as abstract (and therefore does not emit the error message) because the body of the __init__ method is empty. If you populate the body with a single statement, the message will show.

I don't think we could make this change because it will cause to many false positives for interfaces and abstract classes.

The message works fine with:

class Test(object):
    def __init__(self, test_arg):
        a = 1

---

The code is very explicit:

pylint/checkers/variables.py:880

        # Don't check arguments of abstract methods or within an interface.
        is_method = node.is_method()
        if is_method and node.is_abstract():
            return

astroid/scoped_nodes.py:1626

    def is_abstract(self, pass_is_abstract=True):
        """Check if the method is abstract.

        A method is considered abstract if any of the following is true:
        * The only statement is 'raise NotImplementedError'
        * The only statement is 'pass' and pass_is_abstract is True
        * The method is annotated with abc.astractproperty/abc.abstractmethod

        :returns: True if the method is abstract, False otherwise.
        :rtype: bool
        """

I'm closing this but happy to hear objections