[ty] Fix narrowing enum literal unions by member identity#25520
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Typing conformance resultsNo changes detected ✅Current numbersThe percentage of diagnostics emitted that were expected errors held steady at 91.94%. The percentage of expected errors that received a diagnostic held steady at 87.09%. The number of fully passing files held steady at 92/134. |
Memory usage reportMemory usage unchanged ✅ |
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carljm
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Jun 1, 2026
* main: [`pydocstyle`] Improve discoverability of rules enabled for each convention (#24973) [ty] Deduplicate retained use-def place states (#25450) [ty] reduce features of low-level crates depended on by `ty_python_semantic` (#25524) [ty] Fix narrowing enum literal unions by member identity (#25520) [ty] Test tagged union narrowing for named tuples (#25519) [ty] Disallow file-system access in `ty_python_core` (#25518) [ty] Nominal Tagged Union Narrowing (#24916) Commit `scripts/uv.lock` (#25517) Fix potential index out of range in `LineIndex` computation (#25492) [ty] Sync vendored typeshed stubs (#25514) [ty] Add disjointness for protocol method members (#25315) [ty] Use compact sets for more immutable fields (#25476) [ty] Derive `Default` for `FunctionDecoratorInference` (#25482) [ty] Ignore rejected assignments for synthesized bindings (#25340) [ty] Handle cycles in function decorator inference (#25475) docs: fix typo `bin/active` → `bin/activate` in tutorial (#25473) [ty] Narrow bound method overloads by receiver (#24707)
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Summary
Prior to this change, we failed to narrow a union containing an explicitly annotated enum literal (e.g.,
x: list[int] | Literal[Answer.NO]) when comparing it against the corresponding enum member:We were comparing the outer literal types, so the intersection builder failed to recognize that both types represented the
same enum member.
Now, we compare the underlying enum-literal identities instead, restoring narrowing for
is,is not,==, and!=.Closes astral-sh/ty#3606.