fix(types): handle generic setup return type

.pre-commit-config.yaml

@@ -87,7 +87,7 @@ repos:
           - rich
           - setuptools-scm
           - tomli
-          - "types-setuptools>=70.1,!=80.9.0.20251221"
+          - types-setuptools>=80.9
 
   - repo: https://github.com/henryiii/check-sdist
     rev: "v1.3.0"

src/scikit_build_core/_compat/typing.py

@@ -22,14 +22,29 @@
         def assert_never(_: object) -> None:
             msg = "Expected code to be unreachable"
             raise AssertionError(msg)
-
 else:
     from typing import Self, assert_never
 
+if sys.version_info < (3, 13):
+    if typing.TYPE_CHECKING:
+        from typing_extensions import TypeVar
+    else:
+        # The final noqa is a false positive, see https://github.com/astral-sh/ruff/issues/22178
+        def TypeVar(  # noqa: N802
+            *args: object,
+            default: object = None,  # noqa: ARG001
+            **kwargs: object,  # noqa: ARG001
+        ) -> typing.TypeVar:
+            return typing.TypeVar(*args, **kwargs)
+else:
+    from typing import TypeVar
+
+
 __all__ = [
     "Annotated",
     "Self",
     "TypeAlias",
+    "TypeVar",
     "assert_never",
     "get_args",
     "get_origin",

src/scikit_build_core/setuptools/wrapper.py

@@ -8,13 +8,22 @@
 if TYPE_CHECKING:
     from collections.abc import Callable, Sequence
 
+from .._compat.typing import TypeVar
+
 __all__ = ["setup"]
 
 
 def __dir__() -> list[str]:
     return __all__
 
 
+_DistributionT = TypeVar(
+    "_DistributionT",
+    bound="setuptools._distutils.dist.Distribution",
+    default=setuptools.Distribution,
+)
+
+
 def setup(
     *,
     cmake_args: Sequence[str] = (),
@@ -25,8 +34,9 @@ def setup(
     cmake_minimum_required_version: str | None = None,
     cmake_process_manifest_hook: Callable[[list[str]], list[str]] | None = None,
     cmake_install_target: str = "install",
+    distclass: type[_DistributionT] = setuptools.Distribution,  # type: ignore[assignment]
     **kw: Any,
-) -> setuptools.Distribution:
+) -> _DistributionT:
     assert not cmake_install_dir, "cmake_install_dir not supported yet"
     assert not cmake_with_sdist, "cmake_with_sdist not supported yet"
     assert cmake_process_manifest_hook is None, (
@@ -41,5 +51,8 @@ def setup(
         warnings.warn("Set via pyproject.toml", stacklevel=2)
 
     return setuptools.setup(
-        cmake_source_dir=cmake_source_dir, cmake_args=cmake_args, **kw
+        cmake_source_dir=cmake_source_dir,
+        cmake_args=cmake_args,
+        distclass=distclass,
+        **kw,
     )