Seen in Ruff 0.5.7
In the following code, from __future__ import annotations causes the KW_ONLY to become a string.
The dataclasses module can deal with that, but only if the object isn’t in a if TYPE_CHECKING block.
Ruff supports this for things like ClassVar¹, i.e. if a ClassVar is used in a dataclass, Ruff knows the from typing import ClassVar needs to come out of the if TYPE_CHECKING block. However the same doesn’t seem to be true here.
from __future__ import annotations
from dataclasses import KW_ONLY, dataclass
@dataclass
class Test:
a: int
_: KW_ONLY
b: str
¹This is probably the place that should handle KW_ONLY
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/// Returns `true` if an annotation will be inspected at runtime by the `dataclasses` module. |
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/// |
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/// Specifically, detects whether an annotation is to either `dataclasses.InitVar` or |
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/// `typing.ClassVar` within a `@dataclass` class definition. |
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/// |
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/// See: <https://docs.python.org/3/library/dataclasses.html#init-only-variables> |
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pub(crate) fn is_dataclass_meta_annotation(annotation: &Expr, semantic: &SemanticModel) -> bool { |
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if !semantic.seen_module(Modules::DATACLASSES) { |
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return false; |
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} |
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// Determine whether the assignment is in a `@dataclass` class definition. |
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if let ScopeKind::Class(class_def) = semantic.current_scope().kind { |
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if class_def.decorator_list.iter().any(|decorator| { |
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semantic |
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.resolve_qualified_name(map_callable(&decorator.expression)) |
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.is_some_and(|qualified_name| { |
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matches!(qualified_name.segments(), ["dataclasses", "dataclass"]) |
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}) |
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}) { |
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// Determine whether the annotation is `typing.ClassVar` or `dataclasses.InitVar`. |
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return semantic |
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.resolve_qualified_name(map_subscript(annotation)) |
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.is_some_and(|qualified_name| { |
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matches!(qualified_name.segments(), ["dataclasses", "InitVar"]) |
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|| semantic.match_typing_qualified_name(&qualified_name, "ClassVar") |
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}); |
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} |
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} |
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false |
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} |
