Unstructuring of enum.Enum instances in typing.Literal types doesn't work

[daniel-wer]

• cattrs version: 22.2.0
• Python version: 3.9.13
• Operating System: Ubuntu 20.04.1

Description

I was glad to see #231 which fixes the structuring of enum.Enum instances in typing.Literal types. However, the unstructuring doesn't work yet. See this example (adapted from #231).

What I Did

import attr, cattrs, enum
from typing import Literal

class A(enum.Enum):
    BLA = 1

@attr.define
class Works:
    a: A

@attr.define
class Broken:
    a: Literal[A.BLA]

print(cattrs.unstructure(cattrs.structure({"a": 1}, Works)))   # {'a': 1}
print(cattrs.unstructure(cattrs.structure({"a": 1}, Broken)))  # {'a': <A.BLA: 1>}

My temporary fix is rather straightforward, but it would be great if cattrs would work for this out of the box:

import cattrs
from typing import Literal, get_origin

_c = cattrs.GenConverter()
_c.register_unstructure_hook_func(lambda v: get_origin(v) is Literal, _c.unstructure)

[Tinche]

Sorry, for whatever reason I forgot to leave a comment when you created the issue.

You're right, I'll get this fixed for the next version.