[ty] Fix subtyping of intersections containing newtypes of unions vs unions#24087
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AlexWaygood merged 1 commit intomainfrom Mar 20, 2026
Merged
[ty] Fix subtyping of intersections containing newtypes of unions vs unions#24087AlexWaygood merged 1 commit intomainfrom
AlexWaygood merged 1 commit intomainfrom
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charliermarsh
approved these changes
Mar 20, 2026
Typing conformance resultsNo changes detected ✅Current numbersThe percentage of diagnostics emitted that were expected errors held steady at 85.29%. The percentage of expected errors that received a diagnostic held steady at 78.13%. The number of fully passing files held steady at 64/132. |
Memory usage reportMemory usage unchanged ✅ |
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Summary
We recognise a newtype as a subtype of its concrete base type, and we even recognise newtypes of unions as a subtype of their concrete base type, but we do not currently recognise intersections of newtypes of unions as subtypes of the newtype's concrete base type. This PR fixes that.
Fixes astral-sh/ty#2940
Co-authored-by: Brent Westbrook [email protected]
Test Plan
added mdtests that fail on
main