[ty] Validate sentinel names against assignment targets - #27206
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Typing conformance resultsNo changes detected ✅Current numbersThe percentage of diagnostics emitted that were expected errors held steady at 96.84%. The percentage of expected errors that received a diagnostic held steady at 92.11%. The number of fully passing files held steady at 99/133. |
Memory usage reportMemory usage unchanged ✅ |
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Marking this as draft because python/typing#2277 actually proposes to require that type checkers not error on this mismatch. Until that's resolved we shouldn't add this check. |
carljm
marked this pull request as draft
July 27, 2026 06:20
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Summary
Fixes astral-sh/ty#4091.
Report
mismatched-type-namewhen the name passed to Python 3.15builtins.sentinelortyping_extensions.Sentineldoes not match its assignment target. Accept unqualified and exactly class-qualified sentinel names, including nested classes, without accepting incorrect or partially qualified class paths. Preserve normal call inference for malformed constructor arguments, and update the lint documentation, generated rule reference, and ty schema.Test plan
Add mdtests for mismatched builtin and
typing_extensionssentinels across supported Python versions. Cover aliased constructors, positional and keywordrepr, valid and invalid class-qualified names, and nested class paths.