From 0c5ff00e04229483e3c70b73076d4da93a125eff Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Mon, 27 Nov 2023 11:31:05 -0700
Subject: [PATCH] Make sure stuff in compat.h/cc is guarded by a deal.II
 version.

---
 include/aspect/compat.h | 22 ++++++++++++++++++++++
 source/compat.cc        |  7 +++++++
 2 files changed, 29 insertions(+)

diff --git a/include/aspect/compat.h b/include/aspect/compat.h
index 9ed4ae94049..e4bb332af2b 100644
--- a/include/aspect/compat.h
+++ b/include/aspect/compat.h
@@ -1070,6 +1070,11 @@ namespace dealii
 #endif
 
 
+// deal.II versions up to 9.5 had a poorly designed interface of the
+// SphericalManifold class that made it impossible for us to use.
+// This file thus contains a copy of it.
+#if !DEAL_II_VERSION_GTE(9,6,0)
+
 #include <deal.II/grid/manifold.h>
 #include <deal.II/grid/manifold_lib.h>
 
@@ -1213,4 +1218,21 @@ namespace aspect
   };
 }
 
+#else
+
+// For sufficiently new deal.II versions, we can use the deal.II class, but to
+// avoid name clashes, we have to import the class into namespace aspect. Once
+// we rely on these sufficiently new versions of deal.II, we can not only remove
+// the code above, but also the following lines, and in all places where we
+// reference 'aspect::SphericalManifold' simply use 'SphericalManifold' instead
+// (which then refers to the deal.II class).
+
+#include <deal.II/grid/manifold_lib.h>
+namespace aspect
+{
+  using dealii::SphericalManifold;
+}
+
+#endif
+
 #endif
diff --git a/source/compat.cc b/source/compat.cc
index c5d78de7cc1..6648ca76f94 100644
--- a/source/compat.cc
+++ b/source/compat.cc
@@ -21,6 +21,11 @@
 
 #include <aspect/compat.h>
 
+// deal.II versions up to 9.5 had a poorly designed interface of the
+// SphericalManifold class that made it impossible for us to use.
+// This file thus contains a copy of it.
+#if !DEAL_II_VERSION_GTE(9,6,0)
+
 namespace aspect
 {
   namespace
@@ -797,3 +802,5 @@ namespace aspect
   template class SphericalManifold<2>;
   template class SphericalManifold<3>;
 }
+
+#endif