More accurate dataclass types

python · JelleZijlstra · May 21, 2025 · May 17, 2025 · May 17, 2025 · May 17, 2025
commit da7fa70538cdd5be9bca46053d8746ae83036cad
diff --git a/stdlib/@tests/test_cases/check_dataclasses.py b/stdlib/@tests/test_cases/check_dataclasses.py
@@ -90,6 +90,13 @@ def check_other_isdataclass_overloads(x: type, y: object) -> None:
        assert_type(dc.astuple(y), Tuple[Any, ...])
        dc.replace(y)

+class _D: ...
+
+custom_dc = dc.dataclass(
+    _D, init=True,
+)
+assert_type(custom_dc, type[_D])
+

 # Regression test for #11653
 D = dc.make_dataclass(

diff --git a/stdlib/dataclasses.pyi b/stdlib/dataclasses.pyi
@@ -73,10 +73,24 @@ def astuple(obj: DataclassInstance) -> tuple[Any, ...]: ...
 def astuple(obj: DataclassInstance, *, tuple_factory: Callable[[list[Any]], _T]) -> _T: ...
 @overload
 def dataclass(cls: None, /) -> Callable[[type[_T]], type[_T]]: ...
-@overload
-def dataclass(cls: type[_T], /) -> type[_T]: ...

 if sys.version_info >= (3, 11):
+    @overload
+    def dataclass(
+        cls: type[_T],
+        /,
+        *,
+        init: bool = True,
+        repr: bool = True,
+        eq: bool = True,
+        order: bool = False,
+        unsafe_hash: bool = False,
+        frozen: bool = False,
+        match_args: bool = True,
+        kw_only: bool = False,
+        slots: bool = False,
+        weakref_slot: bool = False,
+    ) -> type[_T]: ...
    @overload
    def dataclass(
        *,
@@ -93,6 +107,21 @@ if sys.version_info >= (3, 11):
    ) -> Callable[[type[_T]], type[_T]]: ...

 elif sys.version_info >= (3, 10):
+    @overload
+    def dataclass(
+        cls: type[_T],
+        /,
+        *,
+        init: bool = True,
+        repr: bool = True,
+        eq: bool = True,
+        order: bool = False,
+        unsafe_hash: bool = False,
+        frozen: bool = False,
+        match_args: bool = True,
+        kw_only: bool = False,
+        slots: bool = False,
+    ) -> type[_T]: ...
    @overload
    def dataclass(
        *,
@@ -108,6 +137,18 @@ elif sys.version_info >= (3, 10):
    ) -> Callable[[type[_T]], type[_T]]: ...

 else:
+    @overload
+    def dataclass(
+        cls: type[_T],
+        /,
+        *,
+        init: bool = True,
+        repr: bool = True,
+        eq: bool = True,
+        order: bool = False,
+        unsafe_hash: bool = False,
+        frozen: bool = False,
+    ) -> type[_T]: ...
    @overload
    def dataclass(
        *,