From a067c2ad82eb4551ab93e4ae9b4d6be35aab3485 Mon Sep 17 00:00:00 2001
From: Marc Fehling <mafehling.git@gmail.com>
Date: Tue, 30 Mar 2021 20:40:48 -0600
Subject: [PATCH] Remove assertion from `DoFHandler::get_fe_collection()`.

---
 include/deal.II/dofs/dof_handler.h |  3 --
 source/hp/refinement.cc            | 44 ++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/include/deal.II/dofs/dof_handler.h b/include/deal.II/dofs/dof_handler.h
index 35a7c578a1..53a21d9aa5 100644
--- a/include/deal.II/dofs/dof_handler.h
+++ b/include/deal.II/dofs/dof_handler.h
@@ -2019,9 +2019,6 @@ template <int dim, int spacedim>
 inline const hp::FECollection<dim, spacedim> &
 DoFHandler<dim, spacedim>::get_fe_collection() const
 {
-  Assert(fe_collection.size() > 0,
-         ExcMessage("No finite element collection is associated with "
-                    "this DoFHandler"));
   return fe_collection;
 }
 
diff --git a/source/hp/refinement.cc b/source/hp/refinement.cc
index 5eebda3355..a9b568fc63 100644
--- a/source/hp/refinement.cc
+++ b/source/hp/refinement.cc
@@ -45,6 +45,10 @@ namespace hp
     void
     full_p_adaptivity(const dealii::DoFHandler<dim, spacedim> &dof_handler)
     {
+      if (dof_handler.get_fe_collection().size() == 0)
+        // nothing to do
+        return;
+
       Assert(
         dof_handler.has_hp_capabilities(),
         (typename dealii::DoFHandler<dim, spacedim>::ExcOnlyAvailableWithHP()));
@@ -63,6 +67,10 @@ namespace hp
       const dealii::DoFHandler<dim, spacedim> &dof_handler,
       const std::vector<bool> &                p_flags)
     {
+      if (dof_handler.get_fe_collection().size() == 0)
+        // nothing to do
+        return;
+
       Assert(
         dof_handler.has_hp_capabilities(),
         (typename dealii::DoFHandler<dim, spacedim>::ExcOnlyAvailableWithHP()));
@@ -108,6 +116,10 @@ namespace hp
       const ComparisonFunction<typename identity<Number>::type>
         &compare_coarsen)
     {
+      if (dof_handler.get_fe_collection().size() == 0)
+        // nothing to do
+        return;
+
       Assert(
         dof_handler.has_hp_capabilities(),
         (typename dealii::DoFHandler<dim, spacedim>::ExcOnlyAvailableWithHP()));
@@ -143,6 +155,10 @@ namespace hp
       const ComparisonFunction<typename identity<Number>::type>
         &compare_coarsen)
     {
+      if (dof_handler.get_fe_collection().size() == 0)
+        // nothing to do
+        return;
+
       Assert(
         dof_handler.has_hp_capabilities(),
         (typename dealii::DoFHandler<dim, spacedim>::ExcOnlyAvailableWithHP()));
@@ -236,6 +252,10 @@ namespace hp
       const ComparisonFunction<typename identity<Number>::type>
         &compare_coarsen)
     {
+      if (dof_handler.get_fe_collection().size() == 0)
+        // nothing to do
+        return;
+
       Assert(
         dof_handler.has_hp_capabilities(),
         (typename dealii::DoFHandler<dim, spacedim>::ExcOnlyAvailableWithHP()));
@@ -428,6 +448,10 @@ namespace hp
       const dealii::DoFHandler<dim, spacedim> &dof_handler,
       const Vector<Number> &                   sobolev_indices)
     {
+      if (dof_handler.get_fe_collection().size() == 0)
+        // nothing to do
+        return;
+
       Assert(
         dof_handler.has_hp_capabilities(),
         (typename dealii::DoFHandler<dim, spacedim>::ExcOnlyAvailableWithHP()));
@@ -486,6 +510,10 @@ namespace hp
       const ComparisonFunction<typename identity<Number>::type>
         &compare_coarsen)
     {
+      if (dof_handler.get_fe_collection().size() == 0)
+        // nothing to do
+        return;
+
       Assert(
         dof_handler.has_hp_capabilities(),
         (typename dealii::DoFHandler<dim, spacedim>::ExcOnlyAvailableWithHP()));
@@ -524,6 +552,10 @@ namespace hp
                   const double                             gamma_h,
                   const double                             gamma_n)
     {
+      if (dof_handler.get_fe_collection().size() == 0)
+        // nothing to do
+        return;
+
       AssertDimension(dof_handler.get_triangulation().n_active_cells(),
                       error_indicators.size());
       AssertDimension(dof_handler.get_triangulation().n_active_cells(),
@@ -633,6 +665,10 @@ namespace hp
     void
     force_p_over_h(const dealii::DoFHandler<dim, spacedim> &dof_handler)
     {
+      if (dof_handler.get_fe_collection().size() == 0)
+        // nothing to do
+        return;
+
       Assert(
         dof_handler.has_hp_capabilities(),
         (typename dealii::DoFHandler<dim, spacedim>::ExcOnlyAvailableWithHP()));
@@ -651,6 +687,10 @@ namespace hp
     void
     choose_p_over_h(const dealii::DoFHandler<dim, spacedim> &dof_handler)
     {
+      if (dof_handler.get_fe_collection().size() == 0)
+        // nothing to do
+        return;
+
       Assert(
         dof_handler.has_hp_capabilities(),
         (typename dealii::DoFHandler<dim, spacedim>::ExcOnlyAvailableWithHP()));
@@ -768,6 +808,10 @@ namespace hp
       const unsigned int                       max_difference,
       const unsigned int                       contains_fe_index)
     {
+      if (dof_handler.get_fe_collection().size() == 0)
+        // nothing to do
+        return false;
+
       Assert(
         dof_handler.has_hp_capabilities(),
         (typename dealii::DoFHandler<dim, spacedim>::ExcOnlyAvailableWithHP()));
-- 
2.39.5