Charlie Marsh 9333f15433 [ty] Fix match exhaustiveness for enum | None unions (#22290) ...

## Summary

If we match on an `TestEnum | None`, then when adding a case like
`~Literal[TestEnum.FOO]` (i.e., after `if value == TestEnum.FOO:
return`), we'd distribute `Literal[TestEnum.BAR]` on the entire builder,
creating `None & Literal[TestEnum.BAR]` which simplified to `Never`.
Instead, we should only expand to the remaining members for pieces of
the intersection that contain the enum.

Now, `(TestEnum | None) & ~Literal[TestEnum.FOO] &
~Literal[TestEnum.BAR]` correctly simplifies to `None` instead of
`Never`.

Closes https://github.com/astral-sh/ty/issues/2260.

2025-12-29 22:19:28 -05:00

..

if_expression.md

[ty] Uniformly use "not supported" in diagnostics (#21916)

2025-12-11 15:03:55 +00:00

if_statement.md

[ty] Uniformly use "not supported" in diagnostics (#21916)

2025-12-11 15:03:55 +00:00

match.md

[ty] Fix match exhaustiveness for enum | None unions (#22290)

2025-12-29 22:19:28 -05:00