[red-knot] simplify gradually-equivalent types out of unions and intersections #17467
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Ecosystem results are mostly just changed types in existing error messages. There are a few new |
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I think it makes sense to simplify As the mypy_primer hits on this PR demonstrate, it obviously isn't currently true that we infer I do think we should prioritise fixing the new ecosystem hits, though: we should be inferring |
AlexWaygood
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Apr 18, 2025
dcreager
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Apr 21, 2025
* main: Update pre-commit dependencies (#17506) [red-knot] Simplify visibility constraint handling for `*`-import definitions (#17486) [red-knot] Detect (some) invalid protocols (#17488) [red-knot] Correctly identify protocol classes (#17487) Update dependency ruff to v0.11.6 (#17516) Update Rust crate shellexpand to v3.1.1 (#17512) Update Rust crate proc-macro2 to v1.0.95 (#17510) Update Rust crate rand to v0.9.1 (#17511) Update Rust crate libc to v0.2.172 (#17509) Update Rust crate jiff to v0.2.9 (#17508) Update Rust crate clap to v4.5.37 (#17507) Update astral-sh/setup-uv action to v5.4.2 (#17504) Update taiki-e/install-action digest to 09dc018 (#17503) [red-knot] infer attribute assignments bound in comprehensions (#17396) [red-knot] simplify gradually-equivalent types out of unions and intersections (#17467) [red-knot] pull primer projects to run from file (#17473)
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Summary
If two types are gradually-equivalent, that means they share the same set of possible materializations. There's no need to keep two such types in the same union or intersection; we should simplify them.
Fixes #17465
The one downside here is that now we will simplify e.g.
Unknown | Todo(...)to justUnknown, ifUnknownwas added to the union first. This is correct from a type perspective (they are equivalent types), but it can mean we lose visibility into part of the cause for the type inferring as unknown. I think this is OK, but if we think it's important to avoid this, I can add a special case to try to preserveTodooverUnknown, if we see them both in the same union or intersection.Test Plan
Added and updated mdtests.