Enum.__members__ not recognized

[FichteFoll]

Despite the update in #1195, I still get an error when accessing an Enum's __members__ attribute with mypy 0.521 and Python 3.6.2:

import enum


class NetworkEventName(str, enum.Enum):
    CONNECTED = "connected"
    DISCONNECTED = "disconnected"
    CLOSE_REQUEST = "close_request"
    MESSAGE = "message"
    RAW_LINE = "raw_line"


print(NetworkEventName.__members__)

> mypy /tmp/enum_test.py
/tmp/enum_test.py:12: error: Type[NetworkEventName] has no attribute "__members__"

> python /tmp/enum_test.py
OrderedDict([('CONNECTED', <NetworkEventName.CONNECTED: 'connected'>), ('DISCONNECTED', <NetworkEventName.DISCONNECTED: 'disconnected'>), ('CLOSE_REQUEST', <NetworkEventName.CLOSE_REQUEST: 'close_request'>), ('MESSAGE', <NetworkEventName.MESSAGE: 'message'>), ('RAW_LINE', <NetworkEventName.RAW_LINE: 'raw_line'>)])

typeshed/stdlib/3.4/enum.pyi

Lines 12 to 13 in 385b9c8

	@property
	def __members__(self: Type[_T]) -> Mapping[str, _T]: ...

[JelleZijlstra]

I wonder if this is a mypy bug, since the property is present on the metaclass in typeshed. cc @elazarg who implemented a lot of the metaclass support in mypy.

[elazarg]

It seems to happen due to a spurious "inconsistent metaclass structure".

str implements Sequence, and therefore has ABC in its MRO. This means NetworkEventName has both EnumMeta and ABCMeta in the meta-mro, neither of which is a subclass of the other. This is the pretty much same problem as with IntEnum.
It is easy to work around in mypy, but I really hope it will be possible to avoid it using Protocols. The ad-hoc special casing is not easy to do consistently and maintainably. Until then, I suggest making Enum inherit from ABCMeta if possible.
If the above suggestions are not possible, I can submit a PR to address this specific case.

[elazarg]

(so this is not a mypy bug, in my opinion)

[elazarg]

In essence, this is duplicate of the more general python/mypy#2824

[FichteFoll]

Seems like it, indeed. I'm closing this then.

[elazarg]

Even more general: #1595.