pylint doesn't understand that typing.Dict extends dict

[chkno]

Steps to reproduce

1. Run pylint over this file:

"""Extend dict and Dict."""

from typing import Dict

class LittleDDict(dict):
    """An embellished dict."""

    def embellishment(self) -> None:
        """Extra functionality over dict."""
        print("I have %d items" % len(self))


class BigDDict(Dict[int, str]):
    """An embellished Dict."""

    def embellishment(self) -> None:
        """Extra functionality over Dict."""
        print("I have %d items" % len(self))


def _main() -> None:
    little_d = LittleDDict()
    little_d[3] = "three"
    little_d.setdefault(4, "four")
    little_d.embellishment()

    big_d = BigDDict()
    big_d[3] = "three"
    big_d.setdefault(4, "four")
    big_d.embellishment()

if __name__ == '__main__':
    _main()

Current behavior

$ pylint --reports=n --persistent=n extend_dict.py 
************* Module extend_dict
extend_dict.py:13:0: R0903: Too few public methods (1/2) (too-few-public-methods)
extend_dict.py:28:4: E1137: 'big_d' does not support item assignment (unsupported-assignment-operation)
extend_dict.py:29:4: E1101: Instance of 'BigDDict' has no 'setdefault' member (no-member)

-----------------------------------
Your code has been rated at 3.89/10

Expected behavior

$ pylint --reports=n --persistent=n extend_dict.py 
Your code has been rated at 10.00/10

pylint --version output

pylint 2.1.1
astroid 2.0.4
Python 3.6.5 (default, Jul  5 2018, 03:28:36) 
[GCC 8.1.0]

[PCManticore]

Thanks for reporting an issue, I can reproduce the problem as well.

[radkujawa]

Is there a plan to to fix this bug? I can't upgrade my pylint (from ancient 2.3.1) due to multiple false positives connected to #3129, which is closed in favor of this ticket.

[matt2000]

FWIW, I've also reproduced this issue.

[hippo91]

@chkno @radkujawa @matt2000 i close this issue. The bug doesn't occur any more on master branch thanks to pylint-dev/astroid#921