Basilisk fails union-of-members/enum equivalency in some case.

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
48/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Quiet
Tech stack
python, rust
Domain
compilers, devtools

Research direction

Start with the linked Basilisk playground reproduction and the typing-spec enum-literal-expansion section. Trace the type-checker path for enum types versus complete unions of literal members; done means the sample no longer reports assignment_incompatibility and its assert_type expectation is accepted.

Written by the indexing model from the issue text.

Description

In typing spec at: #enum-literal-expansion.

Likewise, a type checker should treat a complete union of all literal members as equivalent to the enum type:

Code below reports assignment_incompatibility for x

class Answer(enum.Enum):
    Yes = 1
    No = 2

def test4(a: Answer) -> None:
    x: Literal[Answer.Yes, Answer.No] = a
    assert_type(a, Literal[Answer.Yes, Answer.No])

Playground link

This was first reported against pyright but since this was a hole in the conformance suite as well and I opened an issue and PR about it here and discovered basilisk also failed in 1 case.

Dominant language
Rust
Stars
54
Forks
3
No merged PRs in 30d

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