Avoid treating dataclasses.KW_ONLY as typing-only

crates/ruff_linter/resources/test/fixtures/flake8_type_checking/kw_only.py

@@ -0,0 +1,18 @@
+"""Test: avoid marking a `KW_ONLY` annotation as typing-only."""
+
+from __future__ import annotations
+
+from dataclasses import KW_ONLY, dataclass, Field
+
+
+@dataclass
+class Test1:
+    a: int
+    _: KW_ONLY
+    b: str
+
+
+@dataclass
+class Test2:
+    a: int
+    b: Field

crates/ruff_linter/src/rules/flake8_type_checking/helpers.rs

@@ -125,12 +125,14 @@ pub(crate) fn is_dataclass_meta_annotation(annotation: &Expr, semantic: &Semanti
                     matches!(qualified_name.segments(), ["dataclasses", "dataclass"])
                 })
         }) {
-            // Determine whether the annotation is `typing.ClassVar` or `dataclasses.InitVar`.
+            // Determine whether the annotation is `typing.ClassVar`, `dataclasses.InitVar`, or `dataclasses.KW_ONLY`.
             return semantic
                 .resolve_qualified_name(map_subscript(annotation))
                 .is_some_and(|qualified_name| {
-                    matches!(qualified_name.segments(), ["dataclasses", "InitVar"])
-                        || semantic.match_typing_qualified_name(&qualified_name, "ClassVar")
+                    matches!(
+                        qualified_name.segments(),
+                        ["dataclasses", "InitVar" | "KW_ONLY"]
+                    ) || semantic.match_typing_qualified_name(&qualified_name, "ClassVar")
                 });
         }
     }

crates/ruff_linter/src/rules/flake8_type_checking/mod.rs

@@ -40,6 +40,7 @@ mod tests {
     #[test_case(Rule::TypingOnlyFirstPartyImport, Path::new("TCH001.py"))]
     #[test_case(Rule::TypingOnlyStandardLibraryImport, Path::new("TCH003.py"))]
     #[test_case(Rule::TypingOnlyStandardLibraryImport, Path::new("init_var.py"))]
+    #[test_case(Rule::TypingOnlyStandardLibraryImport, Path::new("kw_only.py"))]
     #[test_case(Rule::TypingOnlyStandardLibraryImport, Path::new("snapshot.py"))]
     #[test_case(Rule::TypingOnlyThirdPartyImport, Path::new("TCH002.py"))]
     #[test_case(Rule::TypingOnlyThirdPartyImport, Path::new("quote.py"))]
@@ -77,6 +78,7 @@ mod tests {
 
     #[test_case(Rule::TypingOnlyThirdPartyImport, Path::new("strict.py"))]
     #[test_case(Rule::TypingOnlyStandardLibraryImport, Path::new("init_var.py"))]
+    #[test_case(Rule::TypingOnlyStandardLibraryImport, Path::new("kw_only.py"))]
     fn strict(rule_code: Rule, path: &Path) -> Result<()> {
         let snapshot = format!("strict_{}_{}", rule_code.as_ref(), path.to_string_lossy());
         let diagnostics = test_path(

crates/ruff_linter/src/rules/flake8_type_checking/snapshots/ruff_linter__rules__flake8_type_checking__tests__strict_typing-only-standard-library-import_kw_only.py.snap

@@ -0,0 +1,25 @@
+---
+source: crates/ruff_linter/src/rules/flake8_type_checking/mod.rs
+---
+kw_only.py:5:45: TCH003 [*] Move standard library import `dataclasses.Field` into a type-checking block
+  |
+3 | from __future__ import annotations
+4 | 
+5 | from dataclasses import KW_ONLY, dataclass, Field
+  |                                             ^^^^^ TCH003
+  |
+  = help: Move into type-checking block
+
+ℹ Unsafe fix
+2  2  | 
+3  3  | from __future__ import annotations
+4  4  | 
+5     |-from dataclasses import KW_ONLY, dataclass, Field
+   5  |+from dataclasses import KW_ONLY, dataclass
+   6  |+from typing import TYPE_CHECKING
+   7  |+
+   8  |+if TYPE_CHECKING:
+   9  |+    from dataclasses import Field
+6  10 | 
+7  11 | 
+8  12 | @dataclass

crates/ruff_linter/src/rules/flake8_type_checking/snapshots/ruff_linter__rules__flake8_type_checking__tests__typing-only-standard-library-import_kw_only.py.snap

@@ -0,0 +1,4 @@
+---
+source: crates/ruff_linter/src/rules/flake8_type_checking/mod.rs
+---
+