False negative attribute resolution of function's argument

[stanislavlevin]

Steps to reproduce

Given a file a.py:

def test(val):
    val.somethingwrong()

test(1)

Current behavior

Result of pylint a.py:

------------------------------------
Your code has been rated at 10.00/10

Expected behavior

Pylint should report an error.

pylint --version output

Result of pylint --version output:

pylint 2.7.2
astroid 2.5.1
Python 3.9.2 (default, Feb 26 2021, 15:33:46) 
[GCC 10.2.1 20201125 (ALT Sisyphus 10.2.1-alt2)]

[hippo91]

@stanislavlevin thanks for your report. I don't think it is a pylint bug. The only way to detect an error would be to detect that test parameter is 1 and so doesn't have somethingwrong method. However doing this would necessitate that astroid, the pylint's inference engine has control-flow analysis ability. This is not yet the case and it is really a huge work.

[Pierre-Sassoulas]

mypy does not find this either and typing is its specialty. I think it's safe to say you need to at least add typing if you want proper reporting.

Ie:

class MyClass:
    def somethingwrong(self):
        pass

def test(val:MyClass):
    val.somethingwrong()

test(1)

mypy:

a.py:9: error: Argument 1 to "test" has incompatible type "int"; expected "MyClass"

[stanislavlevin]

I've already realized that it is mypy task and without annotations it is unsolvable at all. So if there are no plans to add support for type hints in Pylint then please close this issue.

[Pierre-Sassoulas]

Closing as a duplicate of #4813