Weak or improper support for overloads

[flisboac]

Bug description

As requested by @DanielNoord , I'm creating this issue with some of the findings I commented about on another issue.

It seems like pylint either:

1. does not apply the correct set of overloads to the usage of an overloaded method; or
2. completely ignores overloads altogether.

Consider the following base code:

"""whatever"""

# Disabling irrelevant checks
# pylint: disable=too-few-public-methods

from abc import ABCMeta, abstractmethod
from dataclasses import dataclass
from typing import Optional, Union
from typing_extensions import overload, TypedDict


@dataclass
class JobDescriptor:
    """whatever"""
    name: str
    location: str


class JobDescriptorData(TypedDict):
    """whatever"""
    name: str
    location: str


JobDescriptorLike = Union[JobDescriptor, JobDescriptorData]


@dataclass
class RunJobResult:
    """whatever"""
    success: bool


class Service(metaclass=ABCMeta):
    """whatever"""
    @overload
    def run_job(self, descriptor: JobDescriptorLike) -> RunJobResult: ...

    @overload
    def run_job(self, *, name: str, location: str) -> RunJobResult: ...

    @abstractmethod
    def run_job(
        self,
        descriptor: Optional[JobDescriptorLike] = None,
        *,
        name: Optional[str] = None,
        location: Optional[str] = None,
    ) -> RunJobResult:
        """whatever"""


class DefaultService(Service):
    """whatever"""

    # SHOULD BE OKAY, but flags "arguments-differ" for `run_job`. Here's the message:
    #
    # > test_pylint.py:60:4: W0221: Number of parameters was 2 in 'Service.run_job'
    # > and is now 4 in overridden 'DefaultService.run_job' method (arguments-differ)
    def run_job(
        self,
        descriptor: Optional[JobDescriptor] = None,
        *,
        name: Optional[str] = None,
        location: Optional[str] = None,
    ) -> RunJobResult:
        """whatever"""

Now, suppose I'm gonna use Service.run_job in some capacity. The comments expose the behaviour I expect pylint to have, including some comparison with mypy (but could be another linter; I used it as means to comparison, just to confirm if I was mistaken or not):

def main(service: Service):
    """whatever"""
    # This should be ALLOWED.
    # Accepted by both mypy and pylint, which is what I'd expect.
    service.run_job(JobDescriptor("job_1", "/a/b/c"))
    service.run_job(name="job_1", location="/a/b/c")
    service.run_job({"name": "job_1", "location": "/a/b/c"})
    data: JobDescriptorData = {"name": "job_1", "location": "/a/b/c"}
    service.run_job(data)

    # This should be DISALLOWED, but pylint does not flag.
    # mypy properly complains.
    # Why did pylint fail to see that the dict is not of the correct shape?
    service.run_job({})
    service.run_job({"property_not_declared": "shall_not_pass"})

    # DISALLOWED, but pylint does not flag.
    # mypy properly complains.
    # Why?
    # There's no signature on which an int is a valid first argument.
    # Using "/," (instead of, or with, "*,") yields no difference.
    service.run_job(1)

    # DISALLOWED, but pylint does not flag.
    # mypy properly complains.
    # Why?
    # There's no signature on which you can specify both `descriptor`
    # and `name`.
    # The @abstractmethod-marked function in Service shouldn't be a
    # signature candidate, because it refers to the implementation.
    service.run_job(JobDescriptor("a", "b"), name="c")

Note that the problem here is the absence of output for some pretty obvious mistakes.

Configuration

# defaults; no custom config whatsoever

Command used

pylint -- test_pylint.py

Pylint output

************* Module test_pylint
test_pylint.py:60:4: W0221: Number of parameters was 2 in 'Service.run_job' and is now 4 in overridden 'DefaultService.run_job' method (arguments-differ)

------------------------------------------------------------------
Your code has been rated at 9.68/10 (previous run: 9.35/10, +0.32)

Expected behavior

Please, see the comments on main function's implementation.

Pylint version

pylint 2.12.2
astroid 2.9.0
Python 3.8.5 (tags/v3.8.5:580fbb0, Jul 20 2020, 15:57:54) [MSC v.1924 64 bit (AMD64)]

OS / Environment

Microsoft Windows 10 Enterprise (v. 10.0.18363 build 18363)

Additional dependencies

No response

[DanielNoord]

Note that the arguments-differ issue is tracked in #5264. I think we should revisit this issue after that has been fixed to see what remains of the various issues mentioned here.

[jacobtylerwalls]

Thanks for the report. @overload is a known missing feature for pylint. In the past I've suggested closing tickets for @overload as duplicates of pylint-dev/astroid#1015, so I'll keep on with that now.