flagged pylint issues are related to very recent merge of pylint-dev/pylint#3782 with fix of issue pylint-dev/pylint#3468

@fmigneault please pay attention to #713 (comment). This code

from enum import Enum, EnumMeta

import six


class FooMeta(EnumMeta):
    pass


class Foo(six.with_metaclass(FooMeta, Enum)):
    bar = 1

produces error with this fix:

foo.py:3: [W0611 unused-import] Unused import six

@tkukushkin
I don't know enough the internals of astroid to address that specific issue of #841 (comment). Maybe @PCManticore (or other dev from astroid) can help?

The problem in is that after six.with_metaclass(FooMeta, Enum) is processed, the ClassDef effectively becomes:

ClassDef.FooMeta(name='FooMeta',
                 doc=None,
                 decorators=None,
                 bases=[<Name.EnumMeta l.6 at 0x7ff0d24e1a10>],
                 body=[<Pass l.7 at 0x7ff0d24e1a90>])

Therefore there is no more reference to six as seen in the source code. At runtime, the class definition is "converted" and doesn't need six anymore. Is there some way to maintain that reference somewhere in the ClassDef for the check to find it?

@fmigneault I completely understand the cause of this problem and I don't know not hacky solutions and PCManticore did not respond to my comment. That's why I didn't make pull request with this transform.

Thanks for the PR @fmigneault !