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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Incorrect deduplication of Enum values in `Union[Literal[1], Literal[SomeEnum.one]]`","articleBody":"This was fixed on 3.9 (by https://github.com/python/cpython/pull/23294 or followups). Here's a test / example:\r\n\r\n```python\r\nfrom enum import Enum\r\nfrom typing import Literal, Union, get_args\r\n\r\n\r\nclass MyEnum(int, Enum):\r\n    foo = 1\r\n\r\ntp = Union[Literal[MyEnum.foo], Literal[1]]\r\nassert len(get_args(tp)) == 2, get_args(tp)\r\n\r\ntp = Union[Literal[1], Literal[MyEnum.foo]]\r\nassert len(get_args(tp)) == 2, get_args(tp)\r\n```\r\n\r\nThese assertions fail on 3.8 since `Union` deduplicates both `Literal`s into the same thing. The reason you need `Literal` here is because enum values are values not types so they can only appear in a Union if they're also within a Literal.\r\n\r\nAs per https://github.com/python/cpython/pull/23294#issuecomment-728659310 maybe the answer here is to not do anything. And in fact I looked into back porting and it was too big of a change to be called a back port. But I didn't see *this specific* issue w/ Enum and Union reported, so I at least wanted to report it and confirm that it is a bug.\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-103706\n* gh-103720\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/adriangb","@type":"Person","name":"adriangb"},"datePublished":"2023-04-17T16:28:17.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/103592/cpython/issues/103592"}