[ty] Extend Liskov checks to cover cases where methods are incompatibly overridden by non-methods #21611
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Diagnostic diff on typing conformance testsChanges were detected when running ty on typing conformance tests--- old-output.txt 2025-11-25 10:33:16.881497031 +0000
+++ new-output.txt 2025-11-25 10:33:20.774498275 +0000
@@ -1,4 +1,4 @@
-fatal[panic] Panicked at /home/runner/.cargo/git/checkouts/salsa-e6f3bb7c2a062968/17bc55d/src/function/execute.rs:469:17 when checking `/home/runner/work/ruff/ruff/typing/conformance/tests/aliases_typealiastype.py`: `infer_definition_types(Id(1a6a3)): execute: too many cycle iterations`
+fatal[panic] Panicked at /home/runner/.cargo/git/checkouts/salsa-e6f3bb7c2a062968/17bc55d/src/function/execute.rs:469:17 when checking `/home/runner/work/ruff/ruff/typing/conformance/tests/aliases_typealiastype.py`: `infer_definition_types(Id(1baa3)): execute: too many cycle iterations`
_directives_deprecated_library.py:15:31: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `int`
_directives_deprecated_library.py:30:26: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `str`
_directives_deprecated_library.py:36:41: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `Self@__add__`
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| Lint rule | Added | Removed | Changed |
|---|---|---|---|
invalid-method-override |
716 | 6 | 0 |
unused-ignore-comment |
0 | 147 | 0 |
| Total | 716 | 153 | 0 |
CodSpeed Performance ReportMerging #21611 will degrade performances by 25.02%Comparing Summary
Benchmarks breakdown
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…self` (#21614) ## Summary For something like this: ```py from typing import Callable def my_lossy_decorator(fn: Callable[..., int]) -> Callable[..., int]: return fn class MyClass: @my_lossy_decorator def method(self) -> int: return 42 ``` we will currently infer the type of `MyClass.method` as a function-like `Callable`, but we will infer the type of `MyClass().method` as a `Callable` that is _not_ function-like. That's because a `CallableType` currently "forgets" whether it was function-like or not during the `bound_self` transformation: https://github.com/astral-sh/ruff/blob/a57e29131125bf05db7379e90c7616eec32624fe/crates/ty_python_semantic/src/types.rs#L10985-L10987 This seems incorrect, and it's quite different to what we do when binding the `self` parameter of `FunctionLiteral` types: `BoundMethod` types are all seen as subtypes of function-like `Callable` supertypes -- here's `BoundMethodType::into_callable_type`: https://github.com/astral-sh/ruff/blob/a57e29131125bf05db7379e90c7616eec32624fe/crates/ty_python_semantic/src/types.rs#L10844-L10860 The bug here is also causing lots of false positives in the ecosystem report on #21611: a decorated method on a subclass is currently not seen as validly overriding an undecorated method with the same signature on a superclass, because the undecorated superclass method is seen as function-like after binding `self` whereas the decorated subclass method is not. Fixing the bug required adding a new API in `protocol_class.rs`, because it turns out that for our purposes in protocol subtyping/assignability, we really do want a callable type to forget its function-like-ness when binding `self`. I initially tried out this change without changing anything in `protocol_class.rs`. However, it resulted in many ecosystem false positives and new false positives on the typing conformance test suite. This is because it would mean that no protocol with a `__call__` method would ever be seen as a subtype of a `Callable` type, since the `__call__` method on the protocol would be seen as being function-like whereas the `Callable` type would not be seen as function-like. ## Test Plan Added an mdtest that fails on `main`
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…ly overridden by non-methods
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Summary
Test Plan