From a97cd49bac3fb7fbdcae10d6050ae94668ede90c Mon Sep 17 00:00:00 2001
From: Peter Munch <peterrmuench@gmail.com>
Date: Sat, 5 Dec 2020 12:29:50 +0100
Subject: [PATCH] Add assert to extract_vtk_patch_info to prevent
 write_higher_order_cells with non hypercube cells

---
 source/base/data_out_base.cc | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/source/base/data_out_base.cc b/source/base/data_out_base.cc
index 0d91d13b26..ae0db5e50a 100644
--- a/source/base/data_out_base.cc
+++ b/source/base/data_out_base.cc
@@ -598,11 +598,17 @@ namespace
   {
     std::array<unsigned int, 3> vtk_cell_id{};
 
-    if (write_higher_order_cells &&
-        patch.reference_cell_type == ReferenceCell::get_hypercube(dim))
+    if (write_higher_order_cells)
       {
-        vtk_cell_id[0] = vtk_lagrange_cell_type[dim];
-        vtk_cell_id[1] = 1;
+        if (patch.reference_cell_type == ReferenceCell::get_hypercube(dim))
+          {
+            vtk_cell_id[0] = vtk_lagrange_cell_type[dim];
+            vtk_cell_id[1] = 1;
+          }
+        else
+          {
+            Assert(false, ExcNotImplemented());
+          }
       }
     else if (patch.reference_cell_type == ReferenceCell::Type::Tri &&
              patch.data.n_cols() == 3)
-- 
2.39.5