Add better error handling for locate_dofs_topological

cpp/dolfinx/fem/DirichletBC.cpp

@@ -55,9 +55,17 @@ find_local_entity_index(const mesh::Topology& topology,
 
   std::vector<std::pair<std::int32_t, int>> entity_indices;
   entity_indices.reserve(entities.size());
+  std::int32_t num_entities_local = e_to_c->num_nodes();
   for (std::int32_t e : entities)
   {
     // Get first attached cell
+    if (num_entities_local <= e)
+    {
+      throw std::out_of_range(
+          "Input entity " + std::to_string(e)
+          + " is larger than the number of entities on this process ("
+          + std::to_string(num_entities_local) + ").");
+    }
     assert(e_to_c->num_links(e) > 0);
     const int cell = e_to_c->links(e).front();
 

python/test/unit/fem/test_bcs.py

@@ -406,3 +406,16 @@ def test_blocked_dof_ownership(shape):
         owned_sub_dofs = boundary_dofs_V[boundary_dofs_V < num_owned_blocked * bs]
         assert len(owned_sub_dofs) == num_owned_sub
         assert len(unrolled_dofs_sub) == len(boundary_dofs_V)
+
+
+def test_bc_index_out_of_range():
+    mesh = create_unit_square(MPI.COMM_WORLD, 4, 4)
+    mesh.topology.create_connectivity(mesh.topology.dim - 1, mesh.topology.dim)
+    facet_map = mesh.topology.index_map(mesh.topology.dim - 1)
+    num_facets_on_proc = facet_map.size_local + facet_map.num_ghosts
+    facets = np.arange(num_facets_on_proc + 1, dtype=np.int32)
+    V = functionspace(mesh, ("Lagrange", 1))
+    with pytest.raises(
+        RuntimeError, match=r".*is bigger than the number of entities on this process.*"
+    ):
+        locate_dofs_topological(V, mesh.topology.dim - 1, facets)