[ty] Recognize __dataclass_transform__ to support SQLModel by rayzeller · Pull Request #23070 · astral-sh/ruff (original) (raw)

For backwards compatibility with pre-3.11 Python, ty now recognizes any function named __dataclass_transform__ as equivalent to typing.dataclass_transform, regardless of which module it is defined in. This matches pyright's behavior and enables proper type checking for libraries like SQLModel that use this pattern.

See: microsoft/pyright#5402

Co-Authored-By: Claude Opus 4.5 noreply@anthropic.com

sharkdp marked this pull request as ready for review

February 4, 2026 16:02

This changes how we extract parameters from dataclass_transform() calls from positional pattern matching to named parameter lookup. This allows custom __dataclass_transform__ functions (like SQLModel's) with different signatures to work correctly.

The previous code used if let [6 params] which silently failed for functions with fewer parameters. Named lookup with defaults is more robust and matches how Python interprets the keyword-only parameters.

Also adds a fallback from field_descriptors to field_specifiers for SQLModel compatibility.

Co-Authored-By: Claude Opus 4.5 noreply@anthropic.com

ntBre added the ty

Multi-file analysis & type inference

label

Feb 5, 2026

sharkdp changed the title[ty] Recognize __dataclass_transform__ as dataclass_transform [ty] Recognize __dataclass_transform__ to support SQLModel

Feb 5, 2026

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