Merge pull request #289 from neutrinoceros/typ/fix_dtype_type_hint

TYP: fix type annotations for _CoordinateValidatorMixin._get_safe_datatype for compatibility with numpy 2.2

src/gpgi/_data_types.py

@@ -42,8 +42,11 @@
 if TYPE_CHECKING:
     from typing import Any, Self
 
+    from numpy.typing import NDArray
+
     from gpgi._typing import FieldMap, HCIArray, Name, RealArray
 
+
 BoundarySpec = tuple[tuple[str, str, str], ...]
 
 
@@ -227,15 +230,15 @@ def _validate_coordinates(self) -> None:
 
             self.coordinates[axis] = coord.astype(coord_dtype, copy=False)
 
-    def _get_safe_datatype(self, reference: np.ndarray | None = None) -> np.dtype:
+    def _get_safe_datatype(
+        self, reference: NDArray[np.floating] | None = None
+    ) -> np.dtype[np.floating]:
         if reference is None:
             reference = self.coordinates[self.axes[0]]
         dt = reference.dtype
         if dt.kind != "f":
             raise ValueError(f"Invalid data type {dt} (expected a float dtype)")
-        # return type should already be correct but
-        # this has the benefit of convincing mypy
-        return np.dtype(dt)
+        return dt
 
 
 class Grid(_CoordinateValidatorMixin):