Overloaded functions and methods with type annotations trigger F811

[asottile]

In GitLab by @wjwwood on May 23, 2018, 23:20

I installed flake8 with:

% sudo -H python3 -m pip install -U flake8

I ran my examples on macOS 10.13.3 using Python 3.6.5 from Homebrew.

Please provide the exact, unmodified output of flake8 --bug-report

% flake8 --bug-report
{
  "dependencies": [
    {
      "dependency": "setuptools",
      "version": "39.0.1"
    }
  ],
  "platform": {
    "python_implementation": "CPython",
    "python_version": "3.6.5",
    "system": "Darwin"
  },
  "plugins": [
    {
      "is_local": false,
      "plugin": "flake8-blind-except",
      "version": "0.1.1"
    },
    {
      "is_local": false,
      "plugin": "flake8-comprehensions",
      "version": "1.4.1"
    },
    {
      "is_local": false,
      "plugin": "flake8-docstrings",
      "version": "1.3.0, pydocstyle: 2.1.1"
    },
    {
      "is_local": false,
      "plugin": "flake8_builtins",
      "version": "0.3"
    },
    {
      "is_local": false,
      "plugin": "flake8_deprecated",
      "version": "1.2"
    },
    {
      "is_local": false,
      "plugin": "flake8_quotes",
      "version": "0.13.0"
    },
    {
      "is_local": false,
      "plugin": "import-order",
      "version": "0.17"
    },
    {
      "is_local": false,
      "plugin": "mccabe",
      "version": "0.6.1"
    },
    {
      "is_local": false,
      "plugin": "new_line_checker",
      "version": "1.6.0"
    },
    {
      "is_local": false,
      "plugin": "pycodestyle",
      "version": "2.3.1"
    },
    {
      "is_local": false,
      "plugin": "pyflakes",
      "version": "1.6.0"
    }
  ],
  "version": "3.5.0"
}

Feature request or bug report:

When using type annotations (Python 3.5+), you can use the typing.overload decorator to redefine functions or methods in order to express how different overloads can map to different return types. Here's a working example based on the example from the Python documentation (https://docs.python.org/3/library/typing.html#typing.overload):

"""Example of type annotations with overload triggering redefinition."""

from typing import Tuple
from typing import overload


@overload
def process(response: None) -> None:
    """Specialize for None."""
    ...


@overload
def process(response: int) -> Tuple[int, str]:
    """Specialize for int."""
    ...


@overload
def process(response: bytes) -> str:
    """Specialize for bytes."""
    ...


def process(response):
    """Implement."""
    print(response)


if __name__ == '__main__':
    process('test')

If you run this (python3 ./example.py) it works:

% python3 ./example.py
test

But if you run flake8 on it you get F811 triggered:

% flake8 example.py
example.py:13:1: F811 redefinition of unused 'process' from line 7
example.py:19:1: F811 redefinition of unused 'process' from line 13
example.py:25:1: F811 redefinition of unused 'process' from line 19

Which I suppose makes sense, and I could disable this check explicitly, but I also think it's a valid use case and pattern so it would be nice if flake8 could use the @overload decorator as a hint to suppress F811 automatically.

[asottile]

In GitLab by @wjwwood on May 23, 2018, 23:20

changed the description

[asottile]

In GitLab by @asottile on Oct 13, 2018, 18:09

This is an issue with upstream pyflakes -- I'd suggest following this issue

[asottile]

In GitLab by @asottile on Oct 23, 2018, 23:51

(closing given the pyflakes issue)

[asottile]

In GitLab by @asottile on Oct 23, 2018, 23:51

closed

[asottile]

In GitLab by @erichiller on Jan 27, 2019, 10:53

It appears the issue has been resolved, and new PyFlakes 2.1.0 released, but I am still having the same issue with Overloads getting F811

[asottile]

In GitLab by @asottile on Jan 27, 2019, 11:00

We have not made a release enabling the new pyflakes yet. It's in progress though, I'm currently waiting on pycodestyle to make a release as well so we can batch up the bumps in the same release

[asottile]

In GitLab by @Melevir on May 13, 2019, 22:35

We have not made a release enabling the new pyflakes yet. It's in progress though, I'm currently waiting on pycodestyle to make a release as well so we can batch up the bumps in the same release

Any progress here? Maybe I can help somehow?

[asottile]

In GitLab by @asottile on May 14, 2019, 24:31

Yes it's fixed, please upgrade to latest

[asottile]

In GitLab by @douardda1 on Apr 2, 2020, 08:17

Looks to me it's not fixed for methods. Am I missing something?

Given a python3.7 (3.7.3, debian buster) venv in which I have:

flake8                      3.7.9          
pyflakes                    2.1.1          

and this 'test.py' file:

from typing import overload


@overload
def test1(arg: str) -> None:
    ...


@overload
def test1(arg: int) -> None:
    ...


def test1(arg) -> None:
    print(arg)

class A:
    @overload
    def test1(self, arg: str) -> None:
        ...

    @overload
    def test1(self, arg: int) -> None:
        ...

    def test1(self, arg) -> None:
        print(arg)

then:

flake8 test.py 
test.py:23:5: F811 redefinition of unused 'test1' from line 19
test.py:27:5: F811 redefinition of unused 'test1' from line 23

Thanks,
David

[asottile]

In GitLab by @asottile on Apr 2, 2020, 08:19

it's fixed on master in pyflakes

[asottile]

In GitLab by @douardda1 on Apr 2, 2020, 08:45

I guess this might answer my next question :-)

Thanks

[asottile]

In GitLab by @adithyabsk on Apr 11, 2020, 19:41

@asottile Can we leave this issue open until the version of pyflakes is updated? It'll help with people tracking this issue.

[asottile]

In GitLab by @asottile on Apr 11, 2020, 19:49

• pyflakes 2.1.x is already in released flake8 3.7.x (what the original issue is about)
• I'm not going to reopen this (or open an issue for every downstream issue that gets fixed since they're not issues on this repository itself)
• if you're interested in updates, I'd suggest following the releases of this repository -- that's far more likely to get activity than this issue anyway upon release

[asottile]

In GitLab by @adithyabsk on Apr 11, 2020, 19:53

I guess that's fair enough.

[asottile]

In GitLab by @asottile on Apr 11, 2020, 19:56

consider also watching !417 for pyflakes specifically, though I'm not sure that helps you all that much

[asottile]

In GitLab by @adithyabsk on Apr 11, 2020, 19:58

@asottile Actually's that more helpful and what I was looking for. I can peg to master once that's merged in.