From ec2c729a84987375e8eef5967f6884f2b6ffb112 Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Tue, 17 Jan 2023 17:49:55 -0700
Subject: [PATCH] Declare the existence of explicit instantiations.

---
 include/deal.II/hp/mapping_collection.h | 21 +++++++++++++++++++++
 source/hp/mapping_collection.cc         |  6 ------
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/include/deal.II/hp/mapping_collection.h b/include/deal.II/hp/mapping_collection.h
index 17dd12662d..15fb484424 100644
--- a/include/deal.II/hp/mapping_collection.h
+++ b/include/deal.II/hp/mapping_collection.h
@@ -151,6 +151,7 @@ namespace hp
   };
 
 
+
   /* --------------- inline functions ------------------- */
 
   template <int dim, int spacedim>
@@ -172,6 +173,26 @@ namespace hp
       push_back(*p);
   }
 
+
+
+  template <int dim, int spacedim>
+  MappingCollection<dim, spacedim>
+    StaticMappingQ1<dim, spacedim>::mapping_collection =
+      MappingCollection<dim, spacedim>(MappingQ1<dim, spacedim>{});
+
+
+#ifndef DOXYGEN
+  // Declare the existence of explicit instantiations of the class
+  // above to avoid certain warnings issues by clang and
+  // newer (LLVM-based) Intel compilers:
+  extern template struct StaticMappingQ1<1, 1>;
+  extern template struct StaticMappingQ1<1, 2>;
+  extern template struct StaticMappingQ1<1, 3>;
+  extern template struct StaticMappingQ1<2, 2>;
+  extern template struct StaticMappingQ1<2, 3>;
+  extern template struct StaticMappingQ1<3, 3>;
+#endif
+
 } // namespace hp
 
 
diff --git a/source/hp/mapping_collection.cc b/source/hp/mapping_collection.cc
index e3d0975240..49647fa51c 100644
--- a/source/hp/mapping_collection.cc
+++ b/source/hp/mapping_collection.cc
@@ -73,12 +73,6 @@ namespace hp
       return mapping;
     }
   } // namespace
-
-  template <int dim, int spacedim>
-  MappingCollection<dim, spacedim>
-    StaticMappingQ1<dim, spacedim>::mapping_collection =
-      MappingCollection<dim, spacedim>(get_static_mapping_q1<dim, spacedim>());
-
 } // namespace hp
 
 
-- 
2.39.5