add checks of cell tag consistency in gmshio

python/dolfinx/io/gmshio.py

@@ -153,6 +153,9 @@ def extract_topology_and_markers(model, name: typing.Optional[str] = None):
             # Create marker array of length of number of tagged cells
             marker = np.full_like(entity_tags[0], tag)
 
+            # Keep track of entity tags to check tag consistency
+            entity_tags = entity_tags[0]
+
             # Group element topology and markers of the same entity type
             entity_type = entity_types[0]
             if entity_type in topologies.keys():
@@ -162,8 +165,15 @@ def extract_topology_and_markers(model, name: typing.Optional[str] = None):
                 topologies[entity_type]["cell_data"] = np.hstack(
                     [topologies[entity_type]["cell_data"], marker]
                 )
+                topologies[entity_type]["entity_tags"] = np.hstack(
+                    [topologies[entity_type]["entity_tags"], entity_tags]
+                )
             else:
-                topologies[entity_type] = {"topology": topology, "cell_data": marker}
+                topologies[entity_type] = {
+                    "topology": topology,
+                    "cell_data": marker,
+                    "entity_tags": entity_tags,
+                }
 
     return topologies
 
@@ -258,6 +268,27 @@ def model_to_mesh(
         # Sort elements by ascending dimension
         perm_sort = np.argsort(cell_dimensions)
 
+        # Check that all cells are tagged once
+        _d = model.getDimension()
+        _elementTypes, _elementTags, _nodeTags = model.mesh.getElements(dim=_d, tag=-1)
+        # assert only one type of elements
+        # assert len(_elementTypes) == 1  # NOTE: already checked in extract_topology_and_markers
+        _elementType_dim = _elementTypes[0]
+        if _elementType_dim not in topologies.keys():
+            raise RuntimeError("All cells are expected to be tagged once; none found")
+        nbcells = len(_elementTags[0])
+        nbcells_tagged = len(topologies[_elementType_dim]["entity_tags"])
+        if nbcells != nbcells_tagged:
+            e = (
+                "All cells are expected to be tagged once;"
+                f"found: {nbcells_tagged}, expected: {nbcells}"
+            )
+            raise RuntimeError(e)
+        nbcells_tagged_once = len(np.unique(topologies[_elementType_dim]["entity_tags"]))
+        if nbcells_tagged != nbcells_tagged_once:
+            e = "All cells are expected to be tagged once; found duplicates"
+            raise RuntimeError(e)
+
         # Broadcast cell type data and geometric dimension
         cell_id = cell_information[perm_sort[-1]]["id"]
         tdim = cell_information[perm_sort[-1]]["dim"]