[ty] Treat declared dataclass fields as instance attributes in `own_instance_member` by charliermarsh · Pull Request #22965 · astral-sh/ruff

charliermarsh · 2026-01-30T01:59:22Z

Summary

The PR adds a check in own_instance_member to avoid treating dataclass fields with defaults as Member::unbound().

I've also fixed cases in which KW_ONLY attributes are shadowed, as in:

from dataclasses import dataclass, KW_ONLY

@dataclass
class Parent:
    _: int

@dataclass
class Child(Parent):
    _: KW_ONLY
    name: str

We now model the correct constructor (def __init__(self, _: int, *, name: str) -> None: ...).

Closes astral-sh/ty#2636.

astral-sh-bot · 2026-01-30T02:01:09Z

Typing conformance results

No changes detected ✅

astral-sh-bot · 2026-01-30T02:02:20Z

`mypy_primer` results

Changes were detected when running on open source projects

pylox (https://github.com/sco1/pylox)
+ pylox/containers/array.py:25:9: error[unresolved-attribute] Object of type `dict[Unknown, Unknown]` has no attribute `append`
+ pylox/containers/array.py:38:9: error[unresolved-attribute] Object of type `dict[Unknown, Unknown]` has no attribute `appendleft`
- pylox/containers/array.py:25:9: warning[possibly-missing-attribute] Attribute `append` may be missing on object of type `dict[Unknown, Unknown] | Unknown | deque[Unknown | None]`
- pylox/containers/array.py:38:9: warning[possibly-missing-attribute] Attribute `appendleft` may be missing on object of type `dict[Unknown, Unknown] | Unknown | deque[Unknown | None]`
- pylox/containers/array.py:69:16: error[no-matching-overload] No overload of bound method `join` matches arguments
- pylox/containers/array.py:99:20: warning[possibly-missing-attribute] Attribute `popleft` may be missing on object of type `dict[Unknown, Unknown] | Unknown | deque[Unknown | None]`
- pylox/containers/array.py:114:9: warning[possibly-missing-attribute] Attribute `reverse` may be missing on object of type `dict[Unknown, Unknown] | Unknown | deque[Unknown | None]`
+ pylox/containers/array.py:99:20: error[unresolved-attribute] Object of type `dict[Unknown, Unknown]` has no attribute `popleft`
+ pylox/containers/array.py:114:9: error[unresolved-attribute] Object of type `dict[Unknown, Unknown]` has no attribute `reverse`
- Found 48 diagnostics
+ Found 47 diagnostics

pwndbg (https://github.com/pwndbg/pwndbg)
- pwndbg/aglib/kernel/__init__.py:264:20: error[unsupported-operator] Operator `+` is not supported between objects of type `None | Unknown` and `Literal[1]`
+ pwndbg/aglib/kernel/__init__.py:264:20: error[unsupported-operator] Operator `+` is not supported between objects of type `Unknown | None` and `Literal[1]`
- pwndbg/aglib/kernel/__init__.py:270:22: error[unsupported-operator] Operator `+` is not supported between objects of type `None | Unknown` and `int`
+ pwndbg/aglib/kernel/__init__.py:270:22: error[unsupported-operator] Operator `+` is not supported between objects of type `Unknown | None` and `int`

prefect (https://github.com/PrefectHQ/prefect)
- src/integrations/prefect-dbt/prefect_dbt/core/settings.py:94:28: error[invalid-assignment] Object of type `dict[Any, Any] | int | dict[str, Any] | ... omitted 4 union elements` is not assignable to `dict[str, Any]`
- src/integrations/prefect-dbt/prefect_dbt/core/settings.py:99:28: error[invalid-assignment] Object of type `int | dict[Any, Any] | float | ... omitted 3 union elements` is not assignable to `dict[str, Any]`
- src/prefect/cli/deploy/_core.py:86:21: error[invalid-assignment] Object of type `dict[Any, Any] | int | dict[str, Any] | ... omitted 4 union elements` is not assignable to `dict[str, Any]`
- src/prefect/cli/deploy/_core.py:87:21: error[invalid-assignment] Object of type `int | dict[Any, Any] | float | ... omitted 3 union elements` is not assignable to `dict[str, Any]`
- src/prefect/deployments/steps/core.py:137:38: error[invalid-argument-type] Argument is incorrect: Argument type `dict[Any, Any] | int | dict[str, Any] | ... omitted 4 union elements` does not satisfy constraints (`str`, `int`, `int | float`, `bool`, `dict[Any, Any]`, `list[Any]`, `None`) of type variable `T`
- src/prefect/flow_engine.py:535:20: error[invalid-return-type] Return type does not match returned value: expected `R@FlowRunEngine | State[Any] | None`, found `(R@FlowRunEngine & ~<class 'NotSet'> & ~Top[State[Any]] & ~Coroutine[object, Never, object]) | (type[NotSet] & ~<class 'NotSet'> & ~Coroutine[object, Never, object]) | Unknown | (PrefectFuture[Unknown] & ~Top[State[Any]] & ~Coroutine[object, Never, object]) | None`
+ src/prefect/flow_engine.py:535:20: error[invalid-return-type] Return type does not match returned value: expected `R@FlowRunEngine | State[Any] | None`, found `(R@FlowRunEngine & ~<class 'NotSet'> & ~Top[State[Any]] & ~Coroutine[object, Never, object]) | (type[NotSet] & ~<class 'NotSet'> & ~Coroutine[object, Never, object]) | Unknown`
- src/prefect/flow_engine.py:539:23: error[invalid-raise] Cannot raise object of type `BaseException | (type[NotSet] & ~<class 'NotSet'>) | (Unknown & ~<class 'NotSet'>)`: Not an instance or subclass of `BaseException`
+ src/prefect/flow_engine.py:539:23: error[invalid-raise] Cannot raise object of type `Exception | (type[NotSet] & ~<class 'NotSet'>)`: Not an instance or subclass of `BaseException`
- src/prefect/flow_engine.py:540:20: error[invalid-return-type] Return type does not match returned value: expected `R@FlowRunEngine | State[Any] | None`, found `BaseException | (type[NotSet] & ~<class 'NotSet'>) | (Unknown & ~<class 'NotSet'>)`
+ src/prefect/flow_engine.py:540:20: error[invalid-return-type] Return type does not match returned value: expected `R@FlowRunEngine | State[Any] | None`, found `Exception | (type[NotSet] & ~<class 'NotSet'>)`
- src/prefect/flow_engine.py:1128:23: error[invalid-raise] Cannot raise object of type `BaseException | (type[NotSet] & ~<class 'NotSet'>) | (Unknown & ~<class 'NotSet'>)`: Not an instance or subclass of `BaseException`
+ src/prefect/flow_engine.py:1128:23: error[invalid-raise] Cannot raise object of type `Exception | (type[NotSet] & ~<class 'NotSet'>)`: Not an instance or subclass of `BaseException`
- src/prefect/flow_engine.py:1129:20: error[invalid-return-type] Return type does not match returned value: expected `R@AsyncFlowRunEngine | State[Any] | None`, found `BaseException | (type[NotSet] & ~<class 'NotSet'>) | (Unknown & ~<class 'NotSet'>)`
+ src/prefect/flow_engine.py:1129:20: error[invalid-return-type] Return type does not match returned value: expected `R@AsyncFlowRunEngine | State[Any] | None`, found `Exception | (type[NotSet] & ~<class 'NotSet'>)`
- src/prefect/task_engine.py:605:20: error[invalid-return-type] Return type does not match returned value: expected `R@SyncTaskRunEngine | State[Any] | None`, found `(R@SyncTaskRunEngine & ~<class 'NotSet'> & ~Top[ResultRecord[Unknown]]) | (type[NotSet] & ~<class 'NotSet'>) | (Unknown & ~<class 'NotSet'> & ~Top[ResultRecord[Unknown]])`
+ src/prefect/task_engine.py:605:20: error[invalid-return-type] Return type does not match returned value: expected `R@SyncTaskRunEngine | State[Any] | None`, found `(R@SyncTaskRunEngine & ~<class 'NotSet'> & ~Top[ResultRecord[Unknown]]) | (type[NotSet] & ~<class 'NotSet'>)`
- src/prefect/task_engine.py:610:23: error[invalid-raise] Cannot raise object of type `BaseException | (type[NotSet] & ~<class 'NotSet'>) | (Unknown & ~<class 'NotSet'>)`: Not an instance or subclass of `BaseException`
+ src/prefect/task_engine.py:610:23: error[invalid-raise] Cannot raise object of type `BaseException | (type[NotSet] & ~<class 'NotSet'>)`: Not an instance or subclass of `BaseException`
- src/prefect/task_engine.py:613:20: error[invalid-return-type] Return type does not match returned value: expected `R@SyncTaskRunEngine | State[Any] | None`, found `BaseException | (type[NotSet] & ~<class 'NotSet'>) | (Unknown & ~<class 'NotSet'>)`
+ src/prefect/task_engine.py:613:20: error[invalid-return-type] Return type does not match returned value: expected `R@SyncTaskRunEngine | State[Any] | None`, found `BaseException | (type[NotSet] & ~<class 'NotSet'>)`
- src/prefect/task_engine.py:1224:20: error[invalid-return-type] Return type does not match returned value: expected `R@AsyncTaskRunEngine | State[Any] | None`, found `(R@AsyncTaskRunEngine & ~<class 'NotSet'> & ~Top[ResultRecord[Unknown]]) | (type[NotSet] & ~<class 'NotSet'>) | (Unknown & ~<class 'NotSet'> & ~Top[ResultRecord[Unknown]])`
+ src/prefect/task_engine.py:1224:20: error[invalid-return-type] Return type does not match returned value: expected `R@AsyncTaskRunEngine | State[Any] | None`, found `(R@AsyncTaskRunEngine & ~<class 'NotSet'> & ~Top[ResultRecord[Unknown]]) | (type[NotSet] & ~<class 'NotSet'>)`
- src/prefect/task_engine.py:1229:23: error[invalid-raise] Cannot raise object of type `BaseException | (type[NotSet] & ~<class 'NotSet'>) | (Unknown & ~<class 'NotSet'>)`: Not an instance or subclass of `BaseException`
+ src/prefect/task_engine.py:1229:23: error[invalid-raise] Cannot raise object of type `BaseException | (type[NotSet] & ~<class 'NotSet'>)`: Not an instance or subclass of `BaseException`
- src/prefect/task_engine.py:1232:20: error[invalid-return-type] Return type does not match returned value: expected `R@AsyncTaskRunEngine | State[Any] | None`, found `BaseException | (type[NotSet] & ~<class 'NotSet'>) | (Unknown & ~<class 'NotSet'>)`
+ src/prefect/task_engine.py:1232:20: error[invalid-return-type] Return type does not match returned value: expected `R@AsyncTaskRunEngine | State[Any] | None`, found `BaseException | (type[NotSet] & ~<class 'NotSet'>)`
- src/prefect/utilities/templating.py:320:13: error[invalid-assignment] Invalid subscript assignment with key of type `object` and value of type `Unknown | int | dict[str, Any] | ... omitted 4 union elements` on object of type `dict[str, Any]`
+ src/prefect/utilities/templating.py:320:13: error[invalid-assignment] Invalid subscript assignment with key of type `object` and value of type `Unknown | dict[str, Any]` on object of type `dict[str, Any]`
- src/prefect/utilities/templating.py:323:16: error[invalid-return-type] Return type does not match returned value: expected `T@resolve_block_document_references | dict[str, Any]`, found `list[Unknown | int | dict[str, Any] | ... omitted 4 union elements]`
+ src/prefect/utilities/templating.py:323:16: error[invalid-return-type] Return type does not match returned value: expected `T@resolve_block_document_references | dict[str, Any]`, found `list[Unknown | dict[str, Any]]`
- src/prefect/utilities/templating.py:437:16: error[invalid-return-type] Return type does not match returned value: expected `T@resolve_variables`, found `dict[object, Unknown | int | float | ... omitted 4 union elements]`
+ src/prefect/utilities/templating.py:437:16: error[invalid-return-type] Return type does not match returned value: expected `T@resolve_variables`, found `dict[object, Unknown]`
- src/prefect/utilities/templating.py:442:16: error[invalid-return-type] Return type does not match returned value: expected `T@resolve_variables`, found `list[Unknown | int | float | ... omitted 4 union elements]`
+ src/prefect/utilities/templating.py:442:16: error[invalid-return-type] Return type does not match returned value: expected `T@resolve_variables`, found `list[Unknown]`
+ src/prefect/workers/base.py:232:13: error[invalid-argument-type] Argument is incorrect: Argument type `str | dict[str, Any]` does not satisfy constraints (`str`, `int`, `int | float`, `bool`, `dict[Any, Any]`, `list[Any]`, `None`) of type variable `T`
- src/prefect/workers/base.py:232:13: error[invalid-argument-type] Argument is incorrect: Argument type `str | int | dict[str, Any] | ... omitted 3 union elements` does not satisfy constraints (`str`, `int`, `int | float`, `bool`, `dict[Any, Any]`, `list[Any]`, `None`) of type variable `T`
- src/prefect/workers/base.py:234:22: error[invalid-argument-type] Argument expression after ** must be a mapping type: Found `int | Unknown | float | ... omitted 4 union elements`
- Found 5375 diagnostics
+ Found 5369 diagnostics

egglog-python (https://github.com/egraphs-good/egglog-python)
+ python/egglog/runtime.py:745:9: error[invalid-assignment] Object of type `() -> Declarations` is not assignable to attribute `__egg_decls_thunk__` of type `() -> Declarations`
- Found 1483 diagnostics
+ Found 1484 diagnostics

core (https://github.com/home-assistant/core)
- homeassistant/util/variance.py:47:12: error[invalid-return-type] Return type does not match returned value: expected `(**_P@ignore_variance) -> _R@ignore_variance`, found `_Wrapped[_P@ignore_variance, int | _R@ignore_variance | float | datetime, _P@ignore_variance, _R@ignore_variance | int | float | datetime]`
- Found 14516 diagnostics
+ Found 14515 diagnostics

Memory usage changes were detected when running on open source projects

trio (https://github.com/python-trio/trio)
-     memo metadata = ~31MB
+     memo metadata = ~33MB

sphinx (https://github.com/sphinx-doc/sphinx)
- TOTAL MEMORY USAGE: ~287MB
+ TOTAL MEMORY USAGE: ~301MB

AlexWaygood

Nice, this looks good

crates/ty_python_semantic/resources/mdtest/dataclasses/fields.md

AlexWaygood · 2026-01-30T13:15:48Z

crates/ty_python_semantic/src/types/class.rs

+            return None;
+        }
+
+        let fields = self.own_fields(db, None, field_policy);


The own_fields() call here is probably somewhat expensive, since it isn't a Salsa-tracked method (ClassType::fields() is currently, but not ClassType::own_fields()). This may be the cause of the 2% perf regression on the tanjun benchmark on Codspeed. We could consider adding Salsa caching to that method and see if it gets rid of the regression -- though the regression is small enough that I don't think it should be blocking; we could try adding Salsa caching as a separate, standalone change.

crates/ty_python_semantic/src/types/class.rs

AlexWaygood · 2026-01-30T13:18:18Z

crates/ty_python_semantic/src/types/class.rs

+            }
+        )
+        .then_some(field.clone())
+        .filter(|field| !field.is_kw_only_sentinel(db))


thsi looks correct, but no tests fail if I make this change

Suggested change

.filter(|field| !field.is_kw_only_sentinel(db))

is it possible to improve the test coverage here?

(Looking at this.)

crates/ty_python_semantic/src/types/class.rs

AlexWaygood

Nice!

[ty] Treat declared dataclass fields as implicitly defined attributes

c26ec43

Move to own_instance_member

0c18616

charliermarsh force-pushed the charlie/imp branch from fc6bc07 to 0c18616 Compare January 30, 2026 02:25

charliermarsh changed the title ~~[ty] Treat declared dataclass fields as implicitly defined attributes~~ [ty] Treat declared dataclass fields as instance attributes in own_instance_member Jan 30, 2026

charliermarsh added the ty Multi-file analysis & type inference label Jan 30, 2026

charliermarsh marked this pull request as ready for review January 30, 2026 02:34

charliermarsh requested review from AlexWaygood, carljm, dcreager and sharkdp as code owners January 30, 2026 02:34

AlexWaygood reviewed Jan 30, 2026

View reviewed changes

Review feedback

352efcf

charliermarsh marked this pull request as draft January 30, 2026 14:19

Handle sentinel

8ce5ced

charliermarsh force-pushed the charlie/imp branch from bbdb716 to 8ce5ced Compare January 30, 2026 17:34

Fix shadowed fields

36bcc40

charliermarsh force-pushed the charlie/imp branch from c2259e6 to 36bcc40 Compare January 30, 2026 17:48

charliermarsh marked this pull request as ready for review January 30, 2026 17:51

AlexWaygood approved these changes Jan 30, 2026

View reviewed changes

Inline

8fb891d

charliermarsh merged commit c2f7cef into main Jan 30, 2026
48 checks passed

charliermarsh deleted the charlie/imp branch January 30, 2026 18:09

sharkdp mentioned this pull request Feb 23, 2026

[ty] Dataclasses: descriptor-typed fields without defaults #23512

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[ty] Treat declared dataclass fields as instance attributes in `own_instance_member`#22965

[ty] Treat declared dataclass fields as instance attributes in `own_instance_member`#22965
charliermarsh merged 6 commits intomainfrom
charlie/imp

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charliermarsh commented Jan 30, 2026 •

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`mypy_primer` results