From 7c3223347d55c131c4daf797b3ba579007e56dca Mon Sep 17 00:00:00 2001
From: Daniel Arndt <daniel.arndt@iwr.uni-heidelberg.de>
Date: Mon, 4 Feb 2019 02:08:20 +0100
Subject: [PATCH] Fix MPI support for older versions

---
 include/deal.II/lac/scalapack.h |  3 +++
 source/lac/scalapack.cc         | 20 ++++++++++++++++----
 source/lac/sparsity_tools.cc    | 30 ++++++++++++++++--------------
 3 files changed, 35 insertions(+), 18 deletions(-)

diff --git a/include/deal.II/lac/scalapack.h b/include/deal.II/lac/scalapack.h
index e44ef1ffe4..ebc212f622 100644
--- a/include/deal.II/lac/scalapack.h
+++ b/include/deal.II/lac/scalapack.h
@@ -203,6 +203,8 @@ public:
    * The user has to ensure that all processes call this with identical @p rank.
    * The @p rank refers to a process of the MPI communicator used to create the process grid
    * of the distributed matrix.
+   *
+   * @note This function requires MPI-3.0 support
    */
   void
   copy_from(const LAPACKFullMatrix<NumberType> &matrix,
@@ -213,6 +215,7 @@ public:
    *
    * @note This function should only be used for relatively small matrix
    * dimensions. It is primarily intended for debugging purposes.
+   * This function requires MPI-3.0 support
    */
   void
   copy_to(FullMatrix<NumberType> &matrix) const;
diff --git a/source/lac/scalapack.cc b/source/lac/scalapack.cc
index 9a5f1bb157..8651557833 100644
--- a/source/lac/scalapack.cc
+++ b/source/lac/scalapack.cc
@@ -361,18 +361,19 @@ void
 ScaLAPACKMatrix<NumberType>::copy_from(const LAPACKFullMatrix<NumberType> &B,
                                        const unsigned int                  rank)
 {
+#  if DEAL_II_MPI_VERSION_GTE(3, 0)
   if (n_rows * n_columns == 0)
     return;
 
   const unsigned int this_mpi_process(
     Utilities::MPI::this_mpi_process(this->grid->mpi_communicator));
 
-#  ifdef DEBUG
+#    ifdef DEBUG
   Assert(Utilities::MPI::max(rank, this->grid->mpi_communicator) == rank,
          ExcMessage("All processes have to call routine with identical rank"));
   Assert(Utilities::MPI::min(rank, this->grid->mpi_communicator) == rank,
          ExcMessage("All processes have to call routine with identical rank"));
-#  endif
+#    endif
 
   // root process has to be active in the grid of A
   if (this_mpi_process == rank)
@@ -484,6 +485,11 @@ ScaLAPACKMatrix<NumberType>::copy_from(const LAPACKFullMatrix<NumberType> &B,
     MPI_Comm_free(&communicator_B);
 
   state = LAPACKSupport::matrix;
+#  else
+  (void)B;
+  (void)rank;
+  AssertThrow(false, ExcNotImplemented());
+#  endif
 }
 
 
@@ -528,18 +534,19 @@ void
 ScaLAPACKMatrix<NumberType>::copy_to(LAPACKFullMatrix<NumberType> &B,
                                      const unsigned int            rank) const
 {
+#  if DEAL_II_MPI_VERSION_GTE(3, 0)
   if (n_rows * n_columns == 0)
     return;
 
   const unsigned int this_mpi_process(
     Utilities::MPI::this_mpi_process(this->grid->mpi_communicator));
 
-#  ifdef DEBUG
+#    ifdef DEBUG
   Assert(Utilities::MPI::max(rank, this->grid->mpi_communicator) == rank,
          ExcMessage("All processes have to call routine with identical rank"));
   Assert(Utilities::MPI::min(rank, this->grid->mpi_communicator) == rank,
          ExcMessage("All processes have to call routine with identical rank"));
-#  endif
+#    endif
 
   if (this_mpi_process == rank)
     {
@@ -650,6 +657,11 @@ ScaLAPACKMatrix<NumberType>::copy_to(LAPACKFullMatrix<NumberType> &B,
   MPI_Group_free(&group_B);
   if (MPI_COMM_NULL != communicator_B)
     MPI_Comm_free(&communicator_B);
+#  else
+  (void)B;
+  (void)rank;
+  AssertThrow(false, ExcNotImplemented());
+#  endif
 }
 
 
diff --git a/source/lac/sparsity_tools.cc b/source/lac/sparsity_tools.cc
index e6698f28aa..e04c9e54f4 100644
--- a/source/lac/sparsity_tools.cc
+++ b/source/lac/sparsity_tools.cc
@@ -994,13 +994,14 @@ namespace SparsityTools
       unsigned int idx = 0;
       for (const auto &sparsity_line : send_data)
         {
-          const int ierr = MPI_Isend(sparsity_line.second.data(),
-                                     sparsity_line.second.size(),
-                                     DEAL_II_DOF_INDEX_MPI_TYPE,
-                                     sparsity_line.first,
-                                     124,
-                                     mpi_comm,
-                                     &requests[idx++]);
+          const int ierr =
+            MPI_Isend(DEAL_II_MPI_CONST_CAST(sparsity_line.second.data()),
+                      sparsity_line.second.size(),
+                      DEAL_II_DOF_INDEX_MPI_TYPE,
+                      sparsity_line.first,
+                      124,
+                      mpi_comm,
+                      &requests[idx++]);
           AssertThrowMPI(ierr);
         }
     }
@@ -1138,13 +1139,14 @@ namespace SparsityTools
       unsigned int idx = 0;
       for (const auto &sparsity_line : send_data)
         {
-          const int ierr = MPI_Isend(sparsity_line.second.data(),
-                                     sparsity_line.second.size(),
-                                     DEAL_II_DOF_INDEX_MPI_TYPE,
-                                     sparsity_line.first,
-                                     124,
-                                     mpi_comm,
-                                     &requests[idx++]);
+          const int ierr =
+            MPI_Isend(DEAL_II_MPI_CONST_CAST(sparsity_line.second.data()),
+                      sparsity_line.second.size(),
+                      DEAL_II_DOF_INDEX_MPI_TYPE,
+                      sparsity_line.first,
+                      124,
+                      mpi_comm,
+                      &requests[idx++]);
           AssertThrowMPI(ierr);
         }
     }
-- 
2.39.5