[ty] Fix decorated methods with PEP 695 type alias return types#22902
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[ty] Fix decorated methods with PEP 695 type alias return types#22902
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When a decorator's return type is a PEP 695 type alias that wraps a `Callable` type, the `propagate_callable_kind` function in `apply_decorator` was not unwrapping the type alias before propagating the function-like kind. This caused methods decorated with such decorators to not have their `self` parameter properly bound when accessed via instances or `super()`, resulting in "missing-argument" errors. The fix adds handling for `Type::TypeAlias` in `propagate_callable_kind` to recursively unwrap the type alias and apply the callable kind to the underlying `Callable` type. Fixes astral-sh/ty#2646
Typing conformance resultsNo changes detected ✅ |
|
carljm
requested review from
AlexWaygood,
dcreager and
sharkdp
as code owners
AlexWaygood
approved these changes
Jan 27, 2026
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When a decorator's return type is a PEP 695 type alias that wraps a
Callabletype, thepropagate_callable_kindfunction inapply_decoratorwas not unwrapping the type alias before propagating the function-like kind.This caused methods decorated with such decorators to not have their
selfparameter properly bound when accessed via instances orsuper(), resulting in "missing-argument" errors.The fix adds handling for
Type::TypeAliasinpropagate_callable_kindto recursively unwrap the type alias and apply the callable kind to the underlyingCallabletype.Fixes astral-sh/ty#2646