Address a clang compiler problem.

geodynamics · Jul 15, 2023 · 08f8e88 · 08f8e88
1 parent 57653ee
commit 08f8e88
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Showing 2 changed files with 27 additions and 21 deletions.
diff --git a/include/aspect/utilities.h b/include/aspect/utilities.h
@@ -1277,31 +1277,16 @@ namespace aspect
       to_voigt_stiffness_vector(const SymmetricTensor<4,3> &input);
 
 
-      namespace internal
-      {
-        constexpr Tensor<3,3> create_levi_civita_tensor_3d()
-        {
-          Tensor<3,3> permutation_operator_3d;
-          permutation_operator_3d[0][1][2]  = 1;
-          permutation_operator_3d[1][2][0]  = 1;
-          permutation_operator_3d[2][0][1]  = 1;
-          permutation_operator_3d[0][2][1]  = -1;
-          permutation_operator_3d[1][0][2]  = -1;
-          permutation_operator_3d[2][1][0]  = -1;
-          return permutation_operator_3d;
-        }
-      }
-
       /**
-       * The Levi-Civita tensor, also called a permutation or "totally antisymmetric" tensor.
+       * Return the Levi-Civita tensor, also called a permutation or "totally antisymmetric" tensor.
        * See https://en.wikipedia.org/wiki/Levi-Civita_symbol for a definition.
-       * See https://en.wikipedia.org/wiki/Levi-Civita_symbol for more info.
        */
-      template<int dim>
-      constexpr Tensor<dim,dim> levi_civita;
-
-      template <> constexpr Tensor<3,3> levi_civita<3> = internal::create_levi_civita_tensor_3d();
+      template <int dim>
+      const Tensor<dim,dim> &levi_civita();
 
+      // Declare the existence of a specialization:
+      template <>
+      const Tensor<3,3> &levi_civita<3>();
     }
 
   }

diff --git a/source/utilities.cc b/source/utilities.cc
@@ -3369,6 +3369,27 @@ namespace aspect
         });
 
       }
+
+
+      template <>
+      const Tensor<3,3> &levi_civita<3>()
+      {
+        static const Tensor<3,3> t =
+          []()
+        {
+          Tensor<3,3> permutation_operator_3d;
+
+          permutation_operator_3d[0][1][2]  = 1;
+          permutation_operator_3d[1][2][0]  = 1;
+          permutation_operator_3d[2][0][1]  = 1;
+          permutation_operator_3d[0][2][1]  = -1;
+          permutation_operator_3d[1][0][2]  = -1;
+          permutation_operator_3d[2][1][0]  = -1;
+          return permutation_operator_3d;
+        }();
+
+        return t;
+      }
     }