[ty] Fix negation upper bounds in constraint sets#21897
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dcreager
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AlexWaygood,
carljm and
sharkdp
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Diagnostic diff on typing conformance testsNo changes detected when running ty on typing conformance tests ✅ |
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sharkdp
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Dec 10, 2025
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| negated_type = ConstraintSet.range(Never, T, Not[int]) | ||
| negated_constraint = ~ConstraintSet.range(Never, T, int) | ||
| static_assert(negated_type != negated_constraint) |
| result = result.and( | ||
| db, | ||
| ConstrainedTypeVar::new_node(db, typevar, lower, upper_element).negate(db), | ||
| ConstrainedTypeVar::new_node(db, typevar, lower, upper_element.negate(db)), |
dcreager
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Dec 10, 2025
…-cycle * origin/main: [ty] Support implicit type of `cls` in signatures (#21771) [ty] add `SyntheticTypedDictType` and implement `normalized` and `is_equivalent_to` (#21784) [ty] Fix disjointness checks with type-of `@final` classes (#21770) [ty] Fix negation upper bounds in constraint sets (#21897)
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This fixes the logic error that @sharkdp found in the constraint set upper bound normalization logic I introduced in #21871.
I had originally claimed that
(T ≤ α & ~β)should simplify into(T ≤ α) ∧ ¬(T ≤ β). But that also suggests thatT ≤ ~βshould simplify to¬(T ≤ β)on its own, and that's not correct.The correct simplification is that
~αis an "atomic" type, not an "intersection" for the purposes of our upper bound simplifcation. So(T ≤ α & ~β)should simplify to(T ≤ α) ∧ (T ≤ ~β). That is, break apart the elements of a (proper) intersection, regardless of whether each element is negated or not.This PR fixes the logic, adds a test case, and updates the comments to be hopefully more clear and accurate.