base/mpi.h: mark a template variable to have "const inline" linkage.

diff --git a/include/deal.II/base/mpi.h b/include/deal.II/base/mpi.h
index bc0aab7339580b3a20d42dfbc541976ace60c930..67a23a047a7aeed104ce74e104302dda8ecd3708 100644 (file)
--- a/include/deal.II/base/mpi.h
+++ b/include/deal.II/base/mpi.h
@@ -1745,7 +1745,7 @@ namespace Utilities
      * not satisfied.
      */
     template <typename T>
-    const MPI_Datatype mpi_type_id_for_type =
+    inline const MPI_Datatype mpi_type_id_for_type =
       internal::MPIDataTypes::mpi_type_id(
         static_cast<std::remove_cv_t<std::remove_reference_t<T>> *>(nullptr));
 #endif