BUG: Fix cast_pointwise_result with all-NA values (#62352)

Author: heoh

pandas/core/arrays/masked.py

@@ -149,6 +149,8 @@ def _from_sequence(cls, scalars, *, dtype=None, copy: bool = False) -> Self:
         return cls(values, mask)
 
     def _cast_pointwise_result(self, values) -> ArrayLike:
+        if isna(values).all():
+            return type(self)._from_sequence(values, dtype=self.dtype)
         values = np.asarray(values, dtype=object)
         result = lib.maybe_convert_objects(values, convert_to_nullable_dtype=True)
         lkind = self.dtype.kind

pandas/tests/extension/test_masked.py

@@ -362,7 +362,15 @@ def check_accumulate(self, ser: pd.Series, op_name: str, skipna: bool):
         tm.assert_series_equal(result, expected)
 
     def test_loc_setitem_with_expansion_preserves_ea_index_dtype(self, data, request):
-        if data.dtype.kind == "b":
-            mark = pytest.mark.xfail(reason="GH#62344 incorrectly casts to object")
-            request.applymarker(mark)
         super().test_loc_setitem_with_expansion_preserves_ea_index_dtype(data)
+
+
+@pytest.mark.parametrize(
+    "arr", [pd.array([True, False]), pd.array([1, 2]), pd.array([1.0, 2.0])]
+)
+def test_cast_pointwise_result_all_na_respects_original_dtype(arr):
+    # GH#62344
+    values = [pd.NA, pd.NA]
+    result = arr._cast_pointwise_result(values)
+    assert result.dtype == arr.dtype
+    assert all(x is pd.NA for x in result)