From bb056d597e259a2c2d61a3470619ab5ff283a6b7 Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Mon, 15 Oct 2018 10:52:27 -0500
Subject: [PATCH] Remove MPI intracomm from Fortran side

---
 CMakeLists.txt          |  4 ----
 src/hdf5_interface.F90  |  3 ---
 src/initialize.F90      | 30 +-----------------------------
 src/message_passing.F90 | 20 +++-----------------
 4 files changed, 4 insertions(+), 53 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 84f21427ae..c16d726629 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -18,7 +18,6 @@ option(profile  "Compile with profiling flags"                   OFF)
 option(debug    "Compile with debug flags"                       OFF)
 option(optimize "Turn on all compiler optimization flags"        OFF)
 option(coverage "Compile with coverage analysis flags"           OFF)
-option(mpif08   "Use Fortran 2008 MPI interface"                 OFF)
 option(dagmc    "Enable support for DAGMC (CAD) geometry"        OFF)
 
 # Maximum number of nested coordinates levels
@@ -474,9 +473,6 @@ if (HDF5_IS_PARALLEL)
 endif()
 if (MPI_ENABLED)
   target_compile_definitions(libopenmc PUBLIC -DOPENMC_MPI)
-  if (mpif08)
-    target_compile_definitions(libopenmc PRIVATE -DOPENMC_MPIF08)
-  endif()
 endif()
 
 # Set git SHA1 hash as a compile definition
diff --git a/src/hdf5_interface.F90 b/src/hdf5_interface.F90
index 8872a84f6a..7856abb507 100644
--- a/src/hdf5_interface.F90
+++ b/src/hdf5_interface.F90
@@ -13,9 +13,6 @@ module hdf5_interface
   use, intrinsic :: ISO_C_BINDING
 
   use error, only: fatal_error
-#ifdef PHDF5
-  use message_passing, only: mpi_intracomm, MPI_INFO_NULL
-#endif
   use string, only: to_c_string, to_f_string
 
   implicit none
diff --git a/src/initialize.F90 b/src/initialize.F90
index 697fc12354..3d805c97d5 100644
--- a/src/initialize.F90
+++ b/src/initialize.F90
@@ -49,45 +49,17 @@ contains
 ! setting up timers, etc.
 !===============================================================================
 
-  function openmc_init_f(intracomm) result(err) bind(C)
-    integer, intent(in), optional :: intracomm  ! MPI intracommunicator
+  function openmc_init_f() result(err) bind(C)
     integer(C_INT) :: err
 
 #ifdef _OPENMP
     character(MAX_WORD_LEN) :: envvar
 #endif
 
-    ! Copy the communicator to a new variable. This is done to avoid changing
-    ! the signature of this subroutine. If MPI is being used but no communicator
-    ! was passed, assume MPI_COMM_WORLD.
-#ifdef OPENMC_MPI
-#ifdef OPENMC_MPIF08
-    type(MPI_Comm), intent(in) :: comm     ! MPI intracommunicator
-    if (present(intracomm)) then
-      comm % MPI_VAL = intracomm
-    else
-      comm = MPI_COMM_WORLD
-    end if
-#else
-    integer :: comm
-    if (present(intracomm)) then
-      comm = intracomm
-    else
-      comm = MPI_COMM_WORLD
-    end if
-#endif
-#endif
-
     ! Start total and initialization timer
     call time_total%start()
     call time_initialize%start()
 
-#ifdef OPENMC_MPI
-    ! Indicate that MPI is turned on
-    mpi_enabled = .true.
-    mpi_intracomm = intracomm
-#endif
-
 #ifdef _OPENMP
     ! Change schedule of main parallel-do loop if OMP_SCHEDULE is set
     call get_environment_variable("OMP_SCHEDULE", envvar)
diff --git a/src/message_passing.F90 b/src/message_passing.F90
index 05219f0f89..37d2034475 100644
--- a/src/message_passing.F90
+++ b/src/message_passing.F90
@@ -2,26 +2,12 @@ module message_passing
 
   use, intrinsic :: ISO_C_BINDING
 
-#ifdef OPENMC_MPI
-#ifdef OPENMC_MPIF08
-  use mpi_f08
-#else
-  use mpi
-#endif
-#endif
-
-  ! The defaults set here for the number of processors, rank, and master and
-  ! mpi_enabled flag are for when MPI is not being used at all, i.e. a serial
-  ! run. In this case, these variables are still used at times.
+  ! The defaults set here for the number of processors, rank, and master and are
+  ! for when MPI is not being used at all, i.e. a serial run. In this case, these
+  ! variables are still used at times.
 
   integer(C_INT), bind(C, name='openmc_n_procs') :: n_procs = 1  ! number of processes
   integer(C_INT), bind(C, name='openmc_rank')    :: rank    = 0  ! rank of process
   logical(C_BOOL), bind(C, name='openmc_master') :: master  = .true. ! master process?
-  logical :: mpi_enabled = .false. ! is MPI in use and initialized?
-#ifdef OPENMC_MPIF08
-  type(MPI_Comm) :: mpi_intracomm  ! MPI intra-communicator
-#else
-  integer :: mpi_intracomm         ! MPI intra-communicator
-#endif
 
 end module message_passing