False negative: Wrong number of arguments for isinstance

[nickdrozd]

Bug description

isinstance(5)
isinstance(5, int, int)

Configuration

No response

Command used

pylint

Pylint output

No warnings

Expected behavior

Pylint should warn that the number of arguments is wrong.

I don't know if this affects other builtin functions.

Pylint version

pylint 3.2.6
astroid 3.2.4
Python 3.11.1 (main, Dec  7 2022, 01:11:44) [GCC 9.4.0]

OS / Environment

No response

Additional dependencies

No response

[rogersheu]

The following comment seems to suggest that addressing this will be difficult.

pylint/pylint/checkers/typecheck.py

Line 1455 in 466c671

# Built-in functions have no argument information.

I tested a number of other built-in functions (hasattr, getattr, bool, int, etc.) and all of them get skipped.

[nickdrozd]

@rogersheu Fixing it for all builtins might be difficult, but fixing it just for isinstance looks easy:

    def _check_isinstance_args(self, node: nodes.Call) -> None:
        if len(node.args) != 2:
            # isinstance called with wrong number of args
            return

Instead of returning, raise the appropriate error instead.

[rogersheu]

Thanks for pointing that out @nickdrozd! I've opened a PR to address this 👌.