fix Dataclass/Pydantic: go-to-def on named arguments in an __init__ call should go to specific fields #1231

[asukaminato0721]

Summary

Fixes #1231

Updated keyword-argument go-to-definition so class-constructor calls prefer class field annotations and fall back to __init__ parameters, which aligns with issue #1231.

Test Plan

Added a class-field keyword-argument definition test

[github-actions]

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅

[Copilot]

Pull request overview

This PR fixes go-to-definition behavior for keyword arguments in class constructor calls. When using go-to-definition on a named argument in a class instantiation (e.g., Foo(x=1)), it now correctly navigates to the class field annotation (x: int) instead of the __init__ parameter. This aligns with the expected behavior for dataclasses and Pydantic models where fields are defined as class attributes.

Changes:

• Enhanced keyword argument definition resolution to prefer class field annotations over __init__ parameters
• Added test coverage for class field keyword argument navigation

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
pyrefly/lib/state/lsp.rs	Implements new logic to resolve keyword argument definitions by checking class fields first, then falling back to __init__ parameters
pyrefly/lib/test/lsp/definition.rs	Adds test case verifying that go-to-definition on keyword arguments in class constructors navigates to class field annotations

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