Subclasses of enum.Enum can't be dumped

[VOsakosa]

Steps to reproduce:

import yaml
import enum
class Spam(enum.Enum):
    Value = 1
yaml.dump(Spam)

gives
TypeError: __reduce_ex__() missing 1 required positional argument: 'proto'
in represent_object(self, data).

My analysis:
The dumping code is calling Spam's __reduce_ex__ method on the class itself and therefore supplies one argument less than needed. Since enum.Enum has a meta class, the normal dumping for type instances is not run.

Adding a representer for enum.EnumMeta is a simple workaround, but I suppose the problem could also be solved by making
the representer for type a multi representer.

[nitzmahone]

One way or another, this shouldn't be too hard to fix for pyyaml 6.0...

That said- I am curious what you're doing that you're serializing actual types- care to share? Serializing instances of custom enums makes total sense (and works fine), but the tests around serializing language infra are ancient (ie, long-predating enum). I'm sure there are a number of other cases like these (off the top of my head, dataclasses, namedtuples, and anything involving abc probably don't work right either), but they're also not done by the vast majority of users.

[VOsakosa]

I was dumping a quick attempt at an ECS, where types were used as keys in a dict. Essentially, a value is saved in a dict with its type as key.
I was a bit hesitant to open this issue because I knew it is an obscure case.:)

[nitzmahone]

fixed by #556