[ty] Add support for dynamic dataclasses via `make_dataclass` by charliermarsh · Pull Request #22586 · astral-sh/ruff

charliermarsh · 2026-01-14T22:20:58Z

Summary

Like #22327, but for dataclasses.

astral-sh-bot · 2026-01-14T22:22:42Z

Typing conformance results

No changes detected ✅

astral-sh-bot · 2026-01-14T22:23:55Z

`mypy_primer` results

Changes were detected when running on open source projects

pydantic (https://github.com/pydantic/pydantic)
- pydantic/_internal/_core_metadata.py:87:54: error[invalid-assignment] Invalid assignment to key "pydantic_js_extra" with declared type `dict[str, int | float | str | ... omitted 3 union elements] | ((dict[str, int | float | str | ... omitted 3 union elements], /) -> None) | ((dict[str, int | float | str | ... omitted 3 union elements], type[Any], /) -> None)` on TypedDict `CoreMetadata`: value of type `dict[object, object]`
+ pydantic/_internal/_core_metadata.py:87:54: error[invalid-assignment] Invalid assignment to key "pydantic_js_extra" with declared type `dict[str, Divergent] | ((dict[str, Divergent], /) -> None) | ((dict[str, Divergent], type[Any], /) -> None)` on TypedDict `CoreMetadata`: value of type `dict[object, object]`
- pydantic/fields.py:949:5: error[invalid-parameter-default] Default value of type `PydanticUndefinedType` is not assignable to annotated parameter type `dict[str, int | float | str | ... omitted 3 union elements] | ((dict[str, int | float | str | ... omitted 3 union elements], /) -> None) | None`
+ pydantic/fields.py:949:5: error[invalid-parameter-default] Default value of type `PydanticUndefinedType` is not assignable to annotated parameter type `dict[str, Divergent] | ((dict[str, Divergent], /) -> None) | None`
- pydantic/fields.py:989:5: error[invalid-parameter-default] Default value of type `PydanticUndefinedType` is not assignable to annotated parameter type `dict[str, int | float | str | ... omitted 3 union elements] | ((dict[str, int | float | str | ... omitted 3 union elements], /) -> None) | None`
+ pydantic/fields.py:989:5: error[invalid-parameter-default] Default value of type `PydanticUndefinedType` is not assignable to annotated parameter type `dict[str, Divergent] | ((dict[str, Divergent], /) -> None) | None`
- pydantic/fields.py:1032:5: error[invalid-parameter-default] Default value of type `PydanticUndefinedType` is not assignable to annotated parameter type `dict[str, int | float | str | ... omitted 3 union elements] | ((dict[str, int | float | str | ... omitted 3 union elements], /) -> None) | None`
+ pydantic/fields.py:1032:5: error[invalid-parameter-default] Default value of type `PydanticUndefinedType` is not assignable to annotated parameter type `dict[str, Divergent] | ((dict[str, Divergent], /) -> None) | None`
- pydantic/fields.py:1072:5: error[invalid-parameter-default] Default value of type `PydanticUndefinedType` is not assignable to annotated parameter type `dict[str, int | float | str | ... omitted 3 union elements] | ((dict[str, int | float | str | ... omitted 3 union elements], /) -> None) | None`
+ pydantic/fields.py:1072:5: error[invalid-parameter-default] Default value of type `PydanticUndefinedType` is not assignable to annotated parameter type `dict[str, Divergent] | ((dict[str, Divergent], /) -> None) | None`
- pydantic/fields.py:1115:5: error[invalid-parameter-default] Default value of type `PydanticUndefinedType` is not assignable to annotated parameter type `dict[str, int | float | str | ... omitted 3 union elements] | ((dict[str, int | float | str | ... omitted 3 union elements], /) -> None) | None`
+ pydantic/fields.py:1115:5: error[invalid-parameter-default] Default value of type `PydanticUndefinedType` is not assignable to annotated parameter type `dict[str, Divergent] | ((dict[str, Divergent], /) -> None) | None`
- pydantic/fields.py:1154:5: error[invalid-parameter-default] Default value of type `PydanticUndefinedType` is not assignable to annotated parameter type `dict[str, int | float | str | ... omitted 3 union elements] | ((dict[str, int | float | str | ... omitted 3 union elements], /) -> None) | None`
+ pydantic/fields.py:1154:5: error[invalid-parameter-default] Default value of type `PydanticUndefinedType` is not assignable to annotated parameter type `dict[str, Divergent] | ((dict[str, Divergent], /) -> None) | None`
- pydantic/fields.py:1194:5: error[invalid-parameter-default] Default value of type `PydanticUndefinedType` is not assignable to annotated parameter type `dict[str, int | float | str | ... omitted 3 union elements] | ((dict[str, int | float | str | ... omitted 3 union elements], /) -> None) | None`
+ pydantic/fields.py:1194:5: error[invalid-parameter-default] Default value of type `PydanticUndefinedType` is not assignable to annotated parameter type `dict[str, Divergent] | ((dict[str, Divergent], /) -> None) | None`
- pydantic/fields.py:1573:13: error[invalid-argument-type] Argument is incorrect: Expected `dict[str, int | float | str | ... omitted 3 union elements] | ((dict[str, int | float | str | ... omitted 3 union elements], /) -> None) | None`, found `Top[dict[Unknown, Unknown]] | (((dict[str, int | float | str | ... omitted 3 union elements], /) -> None) & ~Top[dict[Unknown, Unknown]]) | None`
+ pydantic/fields.py:1573:13: error[invalid-argument-type] Argument is incorrect: Expected `dict[str, Divergent] | ((dict[str, Divergent], /) -> None) | None`, found `Top[dict[Unknown, Unknown]] | (((dict[str, Divergent], /) -> None) & ~Top[dict[Unknown, Unknown]]) | None`

prefect (https://github.com/PrefectHQ/prefect)
- src/integrations/prefect-dbt/prefect_dbt/core/settings.py:94:28: error[invalid-assignment] Object of type `T@resolve_block_document_references | int | dict[str, Any] | ... omitted 4 union elements` is not assignable to `dict[str, Any]`
+ src/integrations/prefect-dbt/prefect_dbt/core/settings.py:94:28: error[invalid-assignment] Object of type `dict[str, Any] | int | T@resolve_block_document_references | ... omitted 4 union elements` is not assignable to `dict[str, Any]`
- src/prefect/cli/deploy/_core.py:86:21: error[invalid-assignment] Object of type `T@resolve_block_document_references | int | dict[str, Any] | ... omitted 4 union elements` is not assignable to `dict[str, Any]`
+ src/prefect/cli/deploy/_core.py:86:21: error[invalid-assignment] Object of type `dict[str, Any] | int | T@resolve_block_document_references | ... omitted 4 union elements` is not assignable to `dict[str, Any]`
- src/prefect/deployments/steps/core.py:137:38: error[invalid-argument-type] Argument is incorrect: Expected `T@resolve_variables`, found `T@resolve_block_document_references | int | dict[str, Any] | ... omitted 4 union elements`
+ src/prefect/deployments/steps/core.py:137:38: error[invalid-argument-type] Argument is incorrect: Expected `T@resolve_variables`, found `dict[str, Any] | int | T@resolve_block_document_references | ... omitted 4 union elements`
- src/prefect/utilities/templating.py:320:13: error[invalid-assignment] Invalid subscript assignment with key of type `object` and value of type `T@resolve_block_document_references | 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 `dict[str, Any] | int | T@resolve_block_document_references | ... omitted 4 union elements` 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 | T@resolve_block_document_references | int | ... omitted 5 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] | int | ... omitted 5 union elements]`
- src/prefect/workers/base.py:232:13: error[invalid-argument-type] Argument is incorrect: Expected `T@resolve_variables`, found `T@resolve_block_document_references | int | dict[str, Any] | ... omitted 4 union elements`
+ src/prefect/workers/base.py:232:13: error[invalid-argument-type] Argument is incorrect: Expected `T@resolve_variables`, found `dict[str, Any] | int | T@resolve_block_document_references | ... omitted 4 union elements`

strawberry (https://github.com/strawberry-graphql/strawberry)
+ strawberry/experimental/pydantic/error_type.py:149:37: warning[unused-ignore-comment] Unused blanket `type: ignore` directive
+ strawberry/experimental/pydantic/object_type.py:255:24: warning[unused-ignore-comment] Unused blanket `type: ignore` directive
- strawberry/experimental/pydantic/object_type.py:271:9: error[unresolved-attribute] Unresolved attribute `_pydantic_type` on type `type`
- strawberry/experimental/pydantic/object_type.py:293:13: error[unresolved-attribute] Unresolved attribute `from_pydantic` on type `type`
- strawberry/experimental/pydantic/object_type.py:295:13: error[unresolved-attribute] Unresolved attribute `to_pydantic` on type `type`
- Found 345 diagnostics
+ Found 344 diagnostics

static-frame (https://github.com/static-frame/static-frame)
- static_frame/core/bus.py:675:16: error[invalid-return-type] Return type does not match returned value: expected `InterGetItemILocReduces[Bus[Any], object_]`, found `InterGetItemILocReduces[Self@iloc | Bus[Any], object_ | Self@iloc]`
+ static_frame/core/bus.py:671:16: error[invalid-return-type] Return type does not match returned value: expected `InterGetItemLocReduces[Bus[Any], object_]`, found `InterGetItemLocReduces[Bus[Any] | Bottom[Series[Any, Any]] | TypeBlocks | ... omitted 6 union elements, object_]`
+ static_frame/core/bus.py:675:16: error[invalid-return-type] Return type does not match returned value: expected `InterGetItemILocReduces[Bus[Any], object_]`, found `InterGetItemILocReduces[Bus[Any] | Bottom[Index[Any]] | Bottom[Series[Any, Any]] | ... omitted 7 union elements, object_ | Self@iloc]`
+ static_frame/core/series.py:772:16: error[invalid-return-type] Return type does not match returned value: expected `InterGetItemILocReduces[Series[Any, Any], TVDtype@Series]`, found `InterGetItemILocReduces[Series[Any, Any] | IndexHierarchy | TypeBlocks | ... omitted 7 union elements, TVDtype@Series]`
+ static_frame/core/series.py:4072:16: error[invalid-return-type] Return type does not match returned value: expected `InterGetItemILocReduces[SeriesHE[Any, Any], TVDtype@SeriesHE]`, found `InterGetItemILocReduces[Bottom[Series[Any, Any]] | Bottom[Index[Any]] | TypeBlocks | ... omitted 8 union elements, TVDtype@SeriesHE]`
+ static_frame/core/yarn.py:418:16: error[invalid-return-type] Return type does not match returned value: expected `InterGetItemILocReduces[Yarn[Any], object_]`, found `InterGetItemILocReduces[Yarn[Any] | Bottom[Index[Any]] | Bottom[Series[Any, Any]] | ... omitted 7 union elements, object_]`
- Found 1821 diagnostics
+ Found 1825 diagnostics

rotki (https://github.com/rotki/rotki)
+ rotkehlchen/chain/decoding/tools.py:96:44: warning[unused-ignore-comment] Unused blanket `type: ignore` directive
- rotkehlchen/chain/decoding/tools.py:97:13: error[invalid-argument-type] Argument to function `decode_transfer_direction` is incorrect: Expected `BTCAddress | ChecksumAddress | SubstrateAddress | SolanaAddress`, found `A@BaseDecoderTools`
+ rotkehlchen/chain/decoding/tools.py:99:13: error[invalid-argument-type] Argument to function `decode_transfer_direction` is incorrect: Expected `Sequence[A@BaseDecoderTools]`, found `Unknown | tuple[BTCAddress, ...] | tuple[ChecksumAddress, ...] | tuple[SubstrateAddress, ...] | tuple[SolanaAddress, ...]`
- rotkehlchen/chain/decoding/tools.py:98:13: error[invalid-argument-type] Argument to function `decode_transfer_direction` is incorrect: Expected `BTCAddress | ChecksumAddress | SubstrateAddress | SolanaAddress | None`, found `A@BaseDecoderTools | None`
+ rotkehlchen/chain/decoding/tools.py:100:62: warning[unused-ignore-comment] Unused blanket `type: ignore` directive
- Found 2049 diagnostics
+ Found 2050 diagnostics

No memory usage changes detected ✅

astral-sh-bot · 2026-01-15T09:23:52Z

`ecosystem-analyzer` results

Lint rule	Added	Removed	Changed
`invalid-return-type`	1	4	4
`invalid-argument-type`	1	2	3
`invalid-assignment`	0	0	5
`unused-ignore-comment`	4	0	0
`unresolved-attribute`	0	3	0
Total	6	9	12

Full report with detailed diff (timing results)

AlexWaygood · 2026-01-15T13:46:02Z

I'm a bit hesitant about this one. The typing spec doesn't say anything about this function AFAIK, and I don't remember seeing any user requests on the issue tracker for us to add special-cased support. Mypy_primer only shows two diagnostics going away in the ecosystem, on strawberry -- and it looks like those lines already have type: ignores on them for mypy.

Meanwhile, this is quite a bit of new code, and the manual parsing of arguments in infer/builder.rs is quite complicated and error-prone.

Do any other type checkers have special-cased support for this function? We do have to draw the line somewhere.

I think I'd feel differently if we could share more of the call-expression-parsing logic with what we've already added for namedtuples (which definitely was necessary), but the schema make_dataclass() expects is just different enough that sharing more of the code seems like it could be pretty difficult?

Another -- much simpler -- way to avoid false positives with the objects returned by this function would be to just special-case the return type so that we infer type[Unknown] rather than type -- that wouldn't involve any custom call-expression parsing.

charliermarsh · 2026-01-15T13:59:12Z

AFAICT, Mypy and Pyright do not support it. But... I would still advocate for us to support it? We have all the infrastructure to do so! And almost all of the new code is in argument parsing -- which is very verbose, but at least fairly mechanical and testable? (E.g., it's much easier to know when we have that right, as opposed to something deep in type inference.) I think I don't agree that this is where we should draw the line, unless it's a feature that we can't support for reasons that I don't yet understand or would be uncovered by your review.

AlexWaygood · 2026-01-15T14:01:58Z

(I'm curious for @carljm's and @dcreager's opinions!)

charliermarsh · 2026-01-15T14:08:36Z

Ditto and am totally fine to be overruled on it of course. I took it as a given that we'd support this given that it's in the type system overview; that may have been a mistake!

AlexWaygood · 2026-01-15T14:10:28Z

Ditto and am totally fine to be overruled on it of course. I took it as a given that we'd support this given that it's in the type system overview; that may have been a mistake!

Well, that issue just says that we don't have any tests for the function right now. But this PR adds a lot more than just test coverage 😆

crates/ty_python_semantic/src/types/infer/builder.rs

MichaReiser · 2026-01-15T14:13:31Z

crates/ty_python_semantic/src/types/class.rs

+    }
+
+    /// Look up an instance member by name (including superclasses).
+    pub(crate) fn instance_member(self, db: &'db dyn Db, name: &str) -> PlaceAndQualifiers<'db> {


It seems unfortunate that we have to repeat all those methods for every dynamic class literal. Can't we share more infrastructure?

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

crates/ty_python_semantic/src/types/class.rs

charliermarsh · 2026-01-16T20:00:38Z

Can probably hold off on further review until #22627 is resolved, since it will have implications for this PR.

charliermarsh · 2026-01-19T13:41:33Z

(Marking as draft while we finish the recursive definition work upstream.)

crates/ty_python_semantic/src/types/infer/builder.rs

charliermarsh · 2026-01-22T19:27:17Z

I'm going to mark as draft because I think we should merge #22792 first.

charliermarsh added the ty Multi-file analysis & type inference label Jan 14, 2026

charliermarsh force-pushed the charlie/functional-dict branch 2 times, most recently from 0c2c95b to c9c3caa Compare January 14, 2026 22:36

charliermarsh marked this pull request as ready for review January 15, 2026 02:58

charliermarsh requested review from AlexWaygood, carljm, dcreager and sharkdp as code owners January 15, 2026 02:58

charliermarsh marked this pull request as draft January 15, 2026 02:59

charliermarsh force-pushed the charlie/functional-dict branch 2 times, most recently from 71f3816 to 929be6b Compare January 15, 2026 03:22

charliermarsh marked this pull request as ready for review January 15, 2026 03:22

charliermarsh force-pushed the charlie/functional-dict branch 2 times, most recently from 37f23f2 to 0bcbb7e Compare January 15, 2026 03:59

charliermarsh requested a review from MichaReiser as a code owner January 15, 2026 03:59

AlexWaygood added the ecosystem-analyzer label Jan 15, 2026

AlexWaygood closed this Jan 15, 2026

AlexWaygood reopened this Jan 15, 2026

MichaReiser reviewed Jan 15, 2026

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charliermarsh force-pushed the charlie/functional-dict branch 2 times, most recently from b968cdf to b66f74a Compare January 15, 2026 20:38

charliermarsh force-pushed the charlie/functional-dict branch 3 times, most recently from 07207c7 to 6e36caa Compare January 16, 2026 14:59

charliermarsh marked this pull request as ready for review January 16, 2026 14:59

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charliermarsh marked this pull request as draft January 19, 2026 13:41

charliermarsh force-pushed the charlie/functional-dict branch 2 times, most recently from ccabd74 to 16f4349 Compare January 21, 2026 23:16

carljm removed their request for review January 21, 2026 23:47

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charliermarsh force-pushed the charlie/functional-dict branch from 74ec01d to 239ac3a Compare January 22, 2026 03:52

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charliermarsh marked this pull request as draft January 22, 2026 18:20

[ty] Add support for dynamic dataclasses via make_dataclass

3e78ed6

charliermarsh force-pushed the charlie/functional-dict branch from c7ab85f to 3e78ed6 Compare January 22, 2026 19:14

charliermarsh marked this pull request as ready for review January 22, 2026 19:16

charliermarsh marked this pull request as draft January 22, 2026 19:27

AlexWaygood mentioned this pull request Jan 26, 2026

[ty] Defer base inference for functional type(...) classes #22792

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charliermarsh commented Jan 14, 2026

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