[ty] fix query cycles in decorated function with parameter defaults#23014
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[ty] fix query cycles in decorated function with parameter defaults#23014
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…meters When a protocol method is decorated (e.g., with `@contextmanager`) and has default parameter values, the type checker would incorrectly report an `invalid-argument-type` error when passing a conforming implementation. The root cause was a query cycle during signature computation. When computing the signature for a function with defaults, `definition_expression_type` was called for each default, which first tries `infer_definition_types`. If we're already in the middle of inferring that definition (e.g., during decorator application), this creates a cycle. The fix uses `infer_deferred_types` directly for default value types, following the same pattern already used for parameter annotations in `function_signature_expression_type`. Since defaults are always deferred (as noted in `infer_function_definition`), we can skip the `infer_definition_types` check and go directly to deferred inference, avoiding the cycle. Additionally, when getting the `propagatable_kind` for a `FunctionLiteral` during decorator application, we now get the kind directly from the function without computing its full signature, which is a related optimization. Fixes: astral-sh/ty#2692 https://claude.ai/code/session_01GZpEtiXNH5JVFUK4ntvUF7
Typing conformance resultsNo changes detected ✅ |
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carljm
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charliermarsh
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Feb 2, 2026
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* main: (48 commits) add info for non_octal permissions (#22972) Fix empty body rule rendering (#23039) [ty] Infer `ParamSpec` from class constructors for callable protocols (#22853) Update NPM Development dependencies (#23030) Update CodSpeedHQ/action action to v4.8.2 (#23029) [ty] remove special handling for `Any()` in match class patterns (#23011) Update Rust crate get-size2 to v0.7.4 (#23022) Update Rust crate insta to v1.46.1 (#23023) Update taiki-e/install-action action to v2.67.11 (#23033) Update Rust crate colored to v3.1.1 (#23031) Update cargo-bins/cargo-binstall action to v1.17.3 (#23028) Update Rust crate uuid to v1.20.0 (#23032) [ty] Avoid using `.node()` for detecting `Self` (#23000) Update Rust crate proc-macro2 to v1.0.106 (#23024) Update actions/setup-python action to v6.2.0 (#23027) [ty] fix query cycles in decorated function with parameter defaults (#23014) Update Rust crate quote to v1.0.44 (#23025) Update Rust crate thiserror to v2.0.18 (#23026) Update Rust crate filetime to v0.2.27 (#23021) Update Rust crate clearscreen to v4.0.3 (#23020) ...
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Fixes astral-sh/ty#2692
Summary
This PR fixes query cycles that occur when processing decorated functions with default parameter values. The issue arises because computing a function's full signature requires evaluating default parameter expressions, which can trigger deferred type inference that may cycle back to the original query.
For
FunctionLiteraltypes, directly check decorator attributes (is_classmethod,is_staticmethod) instead of computing the full callable signature. This avoids unnecessary query cycles while still propagating the callable kind through decorators.When computing parameter default types, use
infer_deferred_typesdirectly instead ofdefinition_expression_type. Since defaults are always deferred (as per the function definition logic), this approach is more efficient and avoids potential cycles (becausedefinition_expression_typere-queriesinfer_definition_typesfor the function definitionTest Plan
Added protocol subtyping test cases in
protocols.mdcovering decorated methods with various configurations. Existing test suite passes without regressions.We also see some significant memory-use reductions on some projects, presumably due to reduced query cycles.