[New-bugs-announce] [issue43595] Can not add a metclass that inherits both ABCMeta & ABC to a Union

[Erez Zinman]

New submission from Erez Zinman <erezinman.programmer at gmail.com>:

Related to Issue #43594.

When running the following code

```
from abc import ABCMeta, ABC
from typing import Union

class MetaclassMixin(ABC):
    pass 

class Meta(MetaclassMixin, ABCMeta):
    pass

print(Union[str, Meta])
```

An exception is raised

 >>> TypeError: descriptor '__subclasses__' of 'type' object needs an argument


Tested on v3.6.9

----------
messages: 389317
nosy: erezinman
priority: normal
severity: normal
status: open
title: Can not add a metclass that inherits both ABCMeta & ABC to a Union
versions: Python 3.6

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue43595>
_______________________________________