Fix: compiler issue with vector<bool> in Field

CHANGELOG.md

@@ -3,6 +3,15 @@
 
 # `GridFormat` 0.5.0
 
+## Fixes
+
+- Some compiler versions raised errors because of the way `Field` instances exported data to `vector<bool>` using `std::ranges`.
+Newer compilers seem to be ok with the code, but nevertheless, it was rewritten to work also with compilers that didn't swallow the old code.
+
+## Features
+
+- The regression tests now run against a newer version of `vtk`, namely `v9.5.2`.
+
 # `GridFormat` 0.4.0
 
 ## Features

gridformat/common/field.hpp

@@ -167,18 +167,25 @@ class Field {
     void _export_to(R& range,
                     std::span<const T> data,
                     std::size_t& offset) const {
-        if constexpr (mdrange_dimension<R> > 1)
+        if constexpr (mdrange_dimension<R> > 1) {
             std::ranges::for_each(range, [&] (std::ranges::range auto& sub_range) {
                 _export_to(sub_range, data, offset);
             });
-        else
-            std::ranges::for_each_n(
-                std::ranges::begin(range),
-                std::min(Ranges::size(range), data.size() - offset),
-                [&] (std::ranges::range_reference_t<R> value) {
-                    value = static_cast<std::ranges::range_value_t<R>>(data[offset++]);
-                }
+        } else {
+            // Note: if the span is over a std::vector<bool>, the use of `std::ranges::copy` or similar broke here.
+            //       It seems to work with more recent compilers and/or c++23, though. We use `std::copy` as a workaround.
+            auto converted_data = data | std::views::drop(offset)
+                                       | std::views::take(std::min(Ranges::size(range), data.size() - offset))
+                                       | std::views::transform([] (const T& value) {
+                                            return static_cast<std::ranges::range_value_t<R>>(value);
+                                        });
+            std::copy(
+                std::ranges::begin(converted_data),
+                std::ranges::end(converted_data),
+                std::ranges::begin(range)
             );
+            offset += Ranges::size(converted_data);
+        }
     }
 };
 

test/test_vtk_file.py

@@ -63,7 +63,7 @@ def _get_grid_and_space_dimension(filename: str) -> Tuple[int, int]:
     return int(dim), int(space_dim)
 
 
-def _check_vtk_file(vtk_reader,
+def _check_vtk_file(vtk_grid,
                     points,
                     space_dim,
                     reference_function: Callable[[list], float],
@@ -72,9 +72,8 @@ def _check_vtk_file(vtk_reader,
     rel_tol = 1e-5
     abs_tol = 1e-3
 
-    output = vtk_reader.GetOutput()
     if not skip_metadata:
-        field_data = output.GetFieldData()
+        field_data = vtk_grid.GetFieldData()
         expected_field_data = ["literal", "string", "numbers"]
         for i in range(field_data.GetNumberOfArrays()):
             name = field_data.GetAbstractArray(i).GetName()
@@ -92,12 +91,12 @@ def _check_vtk_file(vtk_reader,
             reference_function.set_time(time_value)
 
     # precompute cell centers
-    num_cells = output.GetNumberOfCells()
+    num_cells = vtk_grid.GetNumberOfCells()
     points = array(points)
     cell_centers = ndarray(shape=(num_cells, 3))
     for cell_id in range(num_cells):
         ids = vtk.vtkIdList()
-        output.GetCellPoints(cell_id, ids)
+        vtk_grid.GetCellPoints(cell_id, ids)
         corner_indices = [ids.GetId(_i) for _i in range(ids.GetNumberOfIds())]
         cell_centers[cell_id] = np_sum(points[corner_indices], axis=0)
         cell_centers[cell_id] /= float(ids.GetNumberOfIds())
@@ -115,7 +114,7 @@ def _compare_data_array(arr, position_call_back):
                 else:
                     assert isclose(0.0, value[comp], rel_tol=rel_tol, abs_tol=abs_tol)
 
-    point_data = output.GetPointData()
+    point_data = vtk_grid.GetPointData()
     for i in range(point_data.GetNumberOfArrays()):
         name = point_data.GetArrayName(i)
         arr = point_data.GetArray(i)
@@ -125,15 +124,15 @@ def _compare_data_array(arr, position_call_back):
             point_id = 0
             for cell_id in range(num_cells):
                 ids = vtk.vtkIdList()
-                output.GetCellPoints(cell_id, ids)
+                vtk_grid.GetCellPoints(cell_id, ids)
                 for _ in range(ids.GetNumberOfIds()):
                     assert isclose(arr.GetTuple(point_id)[0], float(cell_id))
                     point_id += 1
         else:
             for i in range(arr.GetNumberOfTuples()):
                 _compare_data_array(arr, lambda i: points[i])
 
-    cell_data = output.GetCellData()
+    cell_data = vtk_grid.GetCellData()
     for i in range(cell_data.GetNumberOfArrays()):
         name = cell_data.GetArrayName(i)
         arr = cell_data.GetArray(i)
@@ -154,16 +153,42 @@ def _read_pvd_pieces(filename: str) -> List[_TimeStep]:
 
 
 def _test_vtk(filename: str, skip_metadata: bool, reference_function: Callable[[list], float]):
+    def _grid(reader):
+        return reader.GetOutput()
+
+    # For readers that potentially return partitioned datasets
+    def _merged_partitioned_grid(reader):
+        output = reader.GetOutput()
+        if isinstance(output, vtk.vtkUnstructuredGrid):
+            return output
+        merged = vtk.vtkAppendFilter()
+        iter = output.NewIterator()
+        iter.InitTraversal()
+        while not iter.IsDoneWithTraversal():
+            dataset = iter.GetCurrentDataObject()
+            if dataset:
+                merged.AddInputData(dataset)
+            iter.GoToNextItem()
+        merged.Update()
+        merged_grid = merged.GetOutput()
+        merged_grid.GetFieldData().PassData(reader.GetOutput().GetFieldData())
+        return merged_grid
+
     def _get_points_from_grid(reader):
         points = reader.GetOutput().GetPoints()
         return array([points.GetPoint(i) for i in range(points.GetNumberOfPoints())])
 
+    def _get_points_from_partioned_grid(reader):
+        points = _merged_partitioned_grid(reader).GetPoints()
+        return array([points.GetPoint(i) for i in range(points.GetNumberOfPoints())])
+
     def _get_rectilinear_points(reader):
         output = reader.GetOutput()
         return array([output.GetPoint(i) for i in range(output.GetNumberOfPoints())])
 
     e = VTKErrorObserver()
     ext = splitext(filename)[1]
+    get_grid = _grid
     if ext == ".vtu":
         reader = vtk.vtkXMLUnstructuredGridReader()
         point_collector = _get_points_from_grid
@@ -199,7 +224,8 @@ def _get_rectilinear_points(reader):
         point_collector = _get_rectilinear_points
     elif ext == ".hdf" and "unstructured" in filename:
         reader = vtk.vtkHDFReader()
-        point_collector = _get_points_from_grid
+        point_collector = _get_points_from_partioned_grid
+        get_grid = _merged_partitioned_grid
     else:
         raise NotImplementedError(f"Could not determine suitable reader {filename}")
     reader.AddObserver("ErrorEvent", e)
@@ -210,7 +236,7 @@ def _get_rectilinear_points(reader):
 
     _, space_dim = _get_grid_and_space_dimension(filename)
     is_discontinuous = "discontinuous" in filename
-    _check_vtk_file(reader, point_collector(reader), space_dim, reference_function, skip_metadata, is_discontinuous)
+    _check_vtk_file(get_grid(reader), point_collector(reader), space_dim, reference_function, skip_metadata, is_discontinuous)
 
 
 def test(filename: str, skip_metadata: bool = False) -> int | None: