[ty] Support dataclass-transform field_specifiers
#20888
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Diagnostic diff on typing conformance testsChanges were detected when running ty on typing conformance tests--- old-output.txt 2025-10-16 13:58:15.685593376 +0000
+++ new-output.txt 2025-10-16 13:58:19.040608580 +0000
@@ -1,5 +1,5 @@
fatal[panic] Panicked at /home/runner/.cargo/git/checkouts/salsa-e6f3bb7c2a062968/ef9f932/src/function/execute.rs:402:17 when checking `/home/runner/work/ruff/ruff/typing/conformance/tests/aliases_type_statement.py`: `PEP695TypeAliasType < 'db >::value_type_(Id(d417)): execute: too many cycle iterations`
-fatal[panic] Panicked at /home/runner/.cargo/git/checkouts/salsa-e6f3bb7c2a062968/ef9f932/src/function/execute.rs:402:17 when checking `/home/runner/work/ruff/ruff/typing/conformance/tests/aliases_typealiastype.py`: `infer_definition_types(Id(16c43)): execute: too many cycle iterations`
+fatal[panic] Panicked at /home/runner/.cargo/git/checkouts/salsa-e6f3bb7c2a062968/ef9f932/src/function/execute.rs:402:17 when checking `/home/runner/work/ruff/ruff/typing/conformance/tests/aliases_typealiastype.py`: `infer_definition_types(Id(17443)): execute: too many cycle iterations`
_directives_deprecated_library.py:15:31: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `int`
_directives_deprecated_library.py:30:26: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `str`
_directives_deprecated_library.py:36:41: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `Self@__add__`
@@ -279,6 +279,8 @@
dataclasses_transform_converter.py:121:11: error[too-many-positional-arguments] Too many positional arguments to bound method `__init__`: expected 1, got 7
dataclasses_transform_converter.py:130:31: error[invalid-argument-type] Argument to function `model_field` is incorrect: Expected `(Literal[1], /) -> int`, found `def converter_simple(s: str) -> int`
dataclasses_transform_field.py:49:43: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `(...) -> @Todo(unsupported type[X] special form)`
+dataclasses_transform_field.py:64:16: error[unknown-argument] Argument `id` does not match any known parameter
+dataclasses_transform_field.py:75:1: error[missing-argument] No argument provided for required parameter `name`
dataclasses_transform_field.py:75:16: error[too-many-positional-arguments] Too many positional arguments: expected 0, got 1
dataclasses_transform_func.py:57:1: error[invalid-assignment] Object of type `Literal[3]` is not assignable to attribute `name` of type `str`
dataclasses_transform_func.py:61:6: error[unsupported-operator] Operator `<` is not supported for types `Customer1` and `Customer1`
@@ -288,6 +290,7 @@
dataclasses_transform_func.py:77:36: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `T@create_model_frozen`
dataclasses_transform_func.py:97:1: error[invalid-assignment] Property `id` defined in `Customer3` is read-only
dataclasses_transform_meta.py:60:36: error[unknown-argument] Argument `other_name` does not match any known parameter
+dataclasses_transform_meta.py:66:8: error[missing-argument] No arguments provided for required parameters `id`, `name`
dataclasses_transform_meta.py:66:18: error[too-many-positional-arguments] Too many positional arguments: expected 0, got 2
dataclasses_transform_meta.py:73:6: error[unsupported-operator] Operator `<` is not supported for types `Customer1` and `Customer1`
dataclasses_transform_meta.py:79:6: error[unsupported-operator] Operator `<` is not supported for types `Customer2` and `Customer2`
@@ -898,5 +901,5 @@
typeddicts_usage.py:28:17: error[missing-typed-dict-key] Missing required key 'name' in TypedDict `Movie` constructor
typeddicts_usage.py:28:18: error[invalid-key] Invalid key access on TypedDict `Movie`: Unknown key "title"
typeddicts_usage.py:40:24: error[invalid-type-form] The special form `typing.TypedDict` is not allowed in type expressions. Did you mean to use a concrete TypedDict or `collections.abc.Mapping[str, object]` instead?
-Found 900 diagnostics
+Found 903 diagnostics
WARN A fatal error occurred while checking some files. Not all project files were analyzed. See the diagnostics list above for details. |
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| Lint rule | Added | Removed | Changed |
|---|---|---|---|
invalid-argument-type |
0 | 52 | 0 |
missing-argument |
5 | 21 | 0 |
call-non-callable |
2 | 0 | 0 |
unresolved-attribute |
1 | 0 | 1 |
unused-ignore-comment |
1 | 0 | 0 |
| Total | 9 | 73 | 1 |
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| reveal_type(alice.age) # revealed: int | None | ||
| ``` | ||
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| ### For base-class-based transformers |
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[insert "all your base are belong to us" joke]
Comment on lines
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+702
| fn from_flags(db: &'db dyn Db, flags: DataclassFlags) -> Self { | ||
| let dataclasses_field = known_module_symbol(db, KnownModule::Dataclasses, "field") | ||
| .place | ||
| .ignore_possibly_undefined() | ||
| .unwrap_or_else(Type::unknown); | ||
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| Self::new(db, flags, vec![dataclasses_field].into_boxed_slice()) | ||
| } |
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I am sort-of morbidly curious about what does happen to our inference if you try to define a dataclass, with dataclasses.field for one of the fields, and you're using a custom typeshed that doesn't have dataclasses.field in it. That might be an interesting test, but it's almost certainly not worth spending time on it right now 😄
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…rable * origin/main: [ty] Support dataclass-transform `field_specifiers` (#20888) Bump 0.14.1 (#20925) Standardize syntax error construction (#20903) [`pydoclint`] Implement `docstring-extraneous-parameter` (`DOC102`) (#20376) [ty] Fix panic 'missing root' when handling completion request (#20917) [ty] Run file watching tests serial when using nextest (#20918) [ty] Add version hint for failed stdlib attribute accesses (#20909) More CI improvements (#20920) [ty] Check typeshed VERSIONS for parent modules when reporting failed stdlib imports (#20908)
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* main: [ty] Prefer declared type for invariant collection literals (#20927) [ty] Don't track inferability via different `Type` variants (#20677) [ty] Use declared variable types as bidirectional type context (#20796) [ty] Avoid unnecessarily widening generic specializations (#20875) [ty] Support dataclass-transform `field_specifiers` (#20888) Bump 0.14.1 (#20925) Standardize syntax error construction (#20903) [`pydoclint`] Implement `docstring-extraneous-parameter` (`DOC102`) (#20376) [ty] Fix panic 'missing root' when handling completion request (#20917) [ty] Run file watching tests serial when using nextest (#20918) [ty] Add version hint for failed stdlib attribute accesses (#20909) More CI improvements (#20920) [ty] Check typeshed VERSIONS for parent modules when reporting failed stdlib imports (#20908)
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Summary
Add support for the
field_specifiersparameter ondataclass_transformdecorator calls.closes astral-sh/ty#1068
Conformance test results
All true positives ✔️
Ecosystem analysis
trio: this is the kind of change that I would expect from this PR. The code makes use of a dataclassOutcomewith a_unwrapped: bool = attr.ib(default=False, eq=False, init=False)field that is excluded from the__init__signature, so we now see a bunch of constructor-call-related errors going away.home-assistant/core: They have adomain: str = attr.ib(init=False, repr=False)field and then usedefaultattribute ondataclasses.Field[…]with a type ofdefault: _T | Literal[_MISSING_TYPE.MISSING], so we get those "Object of type_MISSING_TYPEis not callable" errors. I don't really understand how that is supposed to work. Even if_MISSING_TYPEwould be absent from that union, what does this try to call? pyright also issues an error and it doesn't seem to work at runtime? So this looks like a true positive?attrs: Similar here. There are some new diagnostics on code that tries to access.validatoron a field. This does work at runtime, but I'm not sure how that is supposed to type-check (without a custom plugin). pyright errors on this as well.aliasyetTest Plan
Updated tests.