Fix incorrect scope for functools partials

[Alphadelta14]

Steps

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Description

While working on pylint-dev/pylint#4357, I happened to notice an issue with partial functions where a given scope had both the original function and some remote partial usage returned by the same inference call.

I tracked the underlying issue to partials having their parents set the original function parent.

So in the [abbreviated] code from pylint/checkers/utils.py below, func (partial(error_of_type, ...)) gets Module as the parent (and since it has the same name, PartialFunction(name=error_of_type)), both of these values are locals in Module with the same name. This lead to the extremely strange case of error_of_type(handler, exception) inferred as both error_of_type and partial(error_of_type, ...).
The proper parent for partial(error_of_type, ...) should just be the normal assignment to func.

def error_of_type(handler: astroid.ExceptHandler, error_type) -> bool:
    pass

def _except_handlers_ignores_exception(
    handlers: astroid.ExceptHandler, exception
) -> bool:
    func = partial(error_of_type, error_type=(exception,))
    return any(func(handler) for handler in handlers)

def get_exception_handlers(
    node: astroid.node_classes.NodeNG, exception=Exception
) -> Optional[List[astroid.ExceptHandler]]:
    context = find_try_except_wrapper_node(node)
    if isinstance(context, astroid.TryExcept):
        return [
            handler for handler in context.handlers if error_of_type(handler, exception)
        ]
    return []

This also fixes the underlying issue seen in pylint-dev/pylint#2588 / 87b55a6e without a special case.

Type of Changes

	Type
✓	🐛 Bug fix

Related Issue

pylint-dev/pylint#4357

[Pierre-Sassoulas]

I tested in pylint and I got:

___________________________________________________________________________________ test_functional[too_many_arguments] ___________________________________________________________________________________

self = <pylint.testutils.lint_module_test.LintModuleTest object at 0x7f37c98c7730>

    def runTest(self):
>       self._runTest()
E       AssertionError: Wrong results for file "too_many_arguments":
E       
E       Unexpected in testdata:
E         32: too-many-function-args

On :

def func_call():
    """Test we don't emit a FP for https://github.com/PyCQA/pylint/issues/2588"""
    partial_func = partial(root_function, 1, 2, 3)
    partial_func()
    return root_function(1, 2, 3) # false positive too-many-function-args

This is the test case for #2588 (#632 )

[Alphadelta14]

okay. I've figured out how to reproduce that test locally. Will make sure that is addressed!

[Pierre-Sassoulas]

It's working in pylint now 👍