From: Bruno Turcksin <bruno.turcksin@gmail.com>
Date: Wed, 14 Sep 2022 19:37:10 +0000 (+0000)
Subject: Improve support to FE_Nothing in matrix-free hanging_nodes
X-Git-Tag: v9.5.0-rc1~964^2~1
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ca485850c79eb162727ab2002abf20f7318de8f1;p=dealii.git

Improve support to FE_Nothing in matrix-free hanging_nodes
---

diff --git a/include/deal.II/matrix_free/hanging_nodes_internal.h b/include/deal.II/matrix_free/hanging_nodes_internal.h
index 86312effc9..ba20ae6f3c 100644
--- a/include/deal.II/matrix_free/hanging_nodes_internal.h
+++ b/include/deal.II/matrix_free/hanging_nodes_internal.h
@@ -529,6 +529,10 @@ namespace internal
               neighbor->level() == cell->level())
             continue;
 
+          // Ignore if the neighbors are FE_Nothing
+          if (neighbor->get_fe().n_dofs_per_cell() == 0)
+            continue;
+
           face |= 1 << direction;
         }
 
@@ -549,10 +553,16 @@ namespace internal
                 std::find_if(line_to_cells[line_index].begin(),
                              line_to_cells[line_index].end(),
                              [&cell](const auto &edge_neighbor) {
+                               DoFCellAccessor<dim, dim, false> dof_cell(
+                                 &edge_neighbor.first->get_triangulation(),
+                                 edge_neighbor.first->level(),
+                                 edge_neighbor.first->index(),
+                                 &cell->get_dof_handler());
                                return edge_neighbor.first->is_artificial() ==
                                         false &&
                                       edge_neighbor.first->level() <
-                                        cell->level();
+                                        cell->level() &&
+                                      dof_cell.get_fe().n_dofs_per_cell() > 0;
                              });
 
               if (edge_neighbor == line_to_cells[line_index].end())