From 9529857ca9a10045c588728ef1c4822c90e88119 Mon Sep 17 00:00:00 2001
From: Gaurav Dhingra <gauravdhingra.gxyd@gmail.com>
Date: Thu, 10 Apr 2025 14:00:30 +0530
Subject: [PATCH 1/3] use integer handles

---
 src/mpi.f90            | 82 ++++++++++++++++++++++--------------------
 src/mpi_c_bindings.f90 | 81 ++++++++++++++++++++---------------------
 2 files changed, 85 insertions(+), 78 deletions(-)

diff --git a/src/mpi.f90 b/src/mpi.f90
index 4532477..6d27b27 100644
--- a/src/mpi.f90
+++ b/src/mpi.f90
@@ -189,7 +189,7 @@ subroutine MPI_Comm_size_proc(comm, size, ierror)
         integer, intent(out) :: size
         integer, optional, intent(out) :: ierror
         integer :: local_ierr
-        type(c_ptr) :: c_comm
+        integer(kind=8) :: c_comm
 
         c_comm = c_mpi_comm_f2c(comm)
         local_ierr = c_mpi_comm_size(c_comm, size)
@@ -210,7 +210,7 @@ subroutine MPI_Bcast_int_scalar(buffer, count, datatype, root, comm, ierror)
         integer, intent(in) :: datatype
         integer, intent(in) :: comm
         integer, optional, intent(out) :: ierror
-        type(c_ptr) :: c_comm, c_datatype
+        integer(kind=8) :: c_comm, c_datatype
         integer :: local_ierr
         type(c_ptr) :: buffer_ptr
 
@@ -236,7 +236,7 @@ subroutine MPI_Bcast_real_2D(buffer, count, datatype, root, comm, ierror)
         integer, intent(in) :: datatype
         integer, intent(in) :: comm
         integer, optional, intent(out) :: ierror
-        type(c_ptr) :: c_comm, c_datatype
+        integer(kind=8) :: c_comm, c_datatype
         integer :: local_ierr
         type(c_ptr) :: buffer_ptr
 
@@ -263,9 +263,9 @@ subroutine MPI_Allgather_int(sendbuf, sendcount, sendtype, recvbuf, recvcount, r
         integer, intent(in) :: sendtype, recvtype
         integer, intent(in) :: comm
         integer, optional, intent(out) :: ierror
-        type(c_ptr) :: c_comm
+        integer(kind=8) :: c_comm
         integer(c_int) :: local_ierr
-        type(c_ptr) :: c_sendtype, c_recvtype
+        integer(kind=8) :: c_sendtype, c_recvtype
         type(c_ptr) :: sendbuf_ptr, recvbuf_ptr
 
         c_comm = c_mpi_comm_f2c(comm)
@@ -293,9 +293,9 @@ subroutine MPI_Allgather_real(sendbuf, sendcount, sendtype, recvbuf, recvcount,
         integer, intent(in) :: sendtype, recvtype
         integer, intent(in) :: comm
         integer, optional, intent(out) :: ierror
-        type(c_ptr) :: c_comm
+        integer(kind=8) :: c_comm
         integer(c_int) :: local_ierr
-        type(c_ptr) :: c_sendtype, c_recvtype
+        integer(kind=8) :: c_sendtype, c_recvtype
         type(c_ptr) :: sendbuf_ptr, recvbuf_ptr
 
         c_comm = c_mpi_comm_f2c(comm)
@@ -324,7 +324,7 @@ subroutine MPI_Isend_2d(buf, count, datatype, dest, tag, comm, request, ierror)
         integer, intent(out) :: request
         integer, optional, intent(out) :: ierror
         type(c_ptr) :: buf_ptr
-        type(c_ptr) :: c_datatype, c_comm, c_request
+        integer(kind=8) :: c_datatype, c_comm, c_request
         integer(c_int) :: local_ierr
 
         buf_ptr = c_loc(buf)
@@ -353,7 +353,7 @@ subroutine MPI_Isend_3d(buf, count, datatype, dest, tag, comm, request, ierror)
         integer, intent(out) :: request
         integer, optional, intent(out) :: ierror
         type(c_ptr) :: buf_ptr
-        type(c_ptr) :: c_datatype, c_comm, c_request
+        integer(kind=8) :: c_datatype, c_comm, c_request
         integer(c_int) :: local_ierr
 
         buf_ptr = c_loc(buf)
@@ -381,10 +381,10 @@ subroutine MPI_Irecv_proc(buf, count, datatype, source, tag, comm, request, ierr
         integer, intent(in) :: comm
         integer, intent(out) :: request
         integer, optional, intent(out) :: ierror
-        type(c_ptr) :: c_comm
+        integer(kind=8) :: c_comm
         integer(c_int) :: local_ierr
-        type(c_ptr) :: c_datatype
-        type(c_ptr) :: c_request
+        integer(kind=8) :: c_datatype
+        integer(kind=8) :: c_request
 
         c_comm = c_mpi_comm_f2c(comm)
         c_datatype = c_mpi_datatype_f2c(datatype)
@@ -407,7 +407,8 @@ subroutine MPI_Allreduce_scalar(sendbuf, recvbuf, count, datatype, op, comm, ier
         real(8), intent(out), target :: recvbuf
         integer, intent(in) :: count, datatype, op, comm
         integer, intent(out), optional :: ierror
-        type(c_ptr) :: sendbuf_ptr, recvbuf_ptr, c_datatype, c_op, c_comm
+        type(c_ptr) :: sendbuf_ptr, recvbuf_ptr
+        integer(kind=8) :: c_datatype, c_op, c_comm
         integer(c_int) :: local_ierr
 
         if (sendbuf == MPI_IN_PLACE) then
@@ -438,7 +439,8 @@ subroutine MPI_Allreduce_1D_recv_proc(sendbuf, recvbuf, count, datatype, op, com
         real(8), dimension(:), intent(out), target :: recvbuf
         integer, intent(in) :: count, datatype, op, comm
         integer, intent(out), optional :: ierror
-        type(c_ptr) :: sendbuf_ptr, recvbuf_ptr, c_datatype, c_op, c_comm
+        type(c_ptr) :: sendbuf_ptr, recvbuf_ptr
+        integer(kind=8) :: c_datatype, c_op, c_comm
         integer(c_int) :: local_ierr
 
         if (sendbuf == MPI_IN_PLACE) then
@@ -469,7 +471,8 @@ subroutine MPI_Allreduce_1D_real_proc(sendbuf, recvbuf, count, datatype, op, com
         real(8), dimension(:), intent(out), target :: recvbuf
         integer, intent(in) :: count, datatype, op, comm
         integer, intent(out), optional :: ierror
-        type(c_ptr) :: sendbuf_ptr, recvbuf_ptr, c_datatype, c_op, c_comm
+        type(c_ptr) :: sendbuf_ptr, recvbuf_ptr
+        integer(kind=8) :: c_datatype, c_op, c_comm
         integer(c_int) :: local_ierr
 
         sendbuf_ptr = c_loc(sendbuf)
@@ -496,7 +499,8 @@ subroutine MPI_Allreduce_1D_int_proc(sendbuf, recvbuf, count, datatype, op, comm
         integer, dimension(:), intent(out), target :: recvbuf
         integer, intent(in) :: count, datatype, op, comm
         integer, intent(out), optional :: ierror
-        type(c_ptr) :: sendbuf_ptr, recvbuf_ptr, c_datatype, c_op, c_comm
+        type(c_ptr) :: sendbuf_ptr, recvbuf_ptr
+        integer(kind=8) :: c_datatype, c_op, c_comm
         integer(c_int) :: local_ierr
 
         sendbuf_ptr = c_loc(sendbuf)
@@ -527,7 +531,7 @@ subroutine MPI_Barrier_proc(comm, ierror)
         use iso_c_binding, only: c_int, c_ptr
         integer, intent(in) :: comm
         integer, intent(out), optional :: ierror
-        type(c_ptr) :: c_comm
+        integer(kind=8) :: c_comm
         integer(c_int) :: local_ierr
 
         ! Convert Fortran handle to C handle
@@ -549,7 +553,7 @@ subroutine MPI_Comm_rank_proc(comm, rank, ierror)
         integer, intent(in) :: comm
         integer, intent(out) :: rank
         integer, optional, intent(out) :: ierror
-        type(c_ptr) :: c_comm
+        integer(kind=8) :: c_comm
         integer(c_int) :: local_ierr
 
         c_comm = c_mpi_comm_f2c(comm)
@@ -574,7 +578,7 @@ subroutine MPI_Comm_split_type_proc(comm, split_type, key, info, newcomm, ierror
         integer, optional, intent(out) :: ierror
     
         integer(c_int) :: local_ierr
-        type(c_ptr) :: c_comm, c_info, c_new_comm
+        integer(kind=8) :: c_comm, c_info, c_new_comm
     
         ! Convert Fortran communicator and info handles to C pointers.
         c_comm = c_mpi_comm_f2c(comm)
@@ -599,13 +603,14 @@ end subroutine MPI_Comm_split_type_proc
     subroutine MPI_Recv_StatusArray_proc(buf, count, datatype, source, tag, comm, status, ierror)
         use iso_c_binding, only: c_int, c_ptr, c_loc
         use mpi_c_bindings, only: c_mpi_recv, c_mpi_comm_f2c, c_mpi_datatype_f2c, c_mpi_status_c2f
-        real(8), dimension(*), intent(inout) :: buf
+        real(8), dimension(*), intent(inout), target :: buf
         integer, intent(in)  :: count, source, tag, datatype, comm
         integer, intent(out) :: status(MPI_STATUS_SIZE)
         integer, optional, intent(out) :: ierror
     
         integer(c_int) :: local_ierr, status_ierr
-        type(c_ptr) :: c_dtype, c_comm, c_status
+        integer(kind=8) :: c_dtype, c_comm
+        type(c_ptr) :: c_status
         integer(c_int), dimension(MPI_STATUS_SIZE), target :: tmp_status
     
         ! Convert Fortran handles to C handles.
@@ -616,7 +621,7 @@ subroutine MPI_Recv_StatusArray_proc(buf, count, datatype, source, tag, comm, st
         c_status = c_loc(tmp_status)
     
         ! Call the native MPI_Recv.
-        local_ierr = c_mpi_recv(buf, count, c_dtype, source, tag, c_comm, c_status)
+        local_ierr = c_mpi_recv(c_loc(buf), count, c_dtype, source, tag, c_comm, c_status)
     
         ! Convert the C MPI_Status to Fortran status.
         if (local_ierr == MPI_SUCCESS) then
@@ -634,36 +639,37 @@ end subroutine MPI_Recv_StatusArray_proc
       subroutine MPI_Recv_StatusIgnore_proc(buf, count, datatype, source, tag, comm, status, ierror)
         use iso_c_binding, only: c_int, c_ptr, c_loc
         use mpi_c_bindings, only: c_mpi_recv, c_mpi_comm_f2c, c_mpi_datatype_f2c, c_mpi_status_c2f
-        real(8), dimension(*), intent(inout) :: buf
+        real(8), dimension(*), intent(inout), target :: buf
         integer, intent(in)  :: count, source, tag, datatype, comm
         integer, intent(out) :: status
         integer, optional, intent(out) :: ierror
     
         integer(c_int) :: local_ierr, status_ierr
-        type(c_ptr) :: c_dtype, c_comm, c_status
+        integer(kind=8) :: c_dtype, c_comm
+        type(c_ptr) :: c_status
         integer(c_int), dimension(MPI_STATUS_SIZE), target :: tmp_status
-    
+
         ! Convert Fortran handles to C handles.
         c_dtype = c_mpi_datatype_f2c(datatype)
         c_comm  = c_mpi_comm_f2c(comm)
-    
+
         ! Use a local temporary MPI_Status (as an array of c_int)
         c_status = c_loc(tmp_status)
-    
+
         ! Call the native MPI_Recv.
-        local_ierr = c_mpi_recv(buf, count, c_dtype, source, tag, c_comm, c_status)
-    
+        local_ierr = c_mpi_recv(c_loc(buf), count, c_dtype, source, tag, c_comm, c_status)
+
         ! Convert the C MPI_Status to Fortran status.
         if (local_ierr == MPI_SUCCESS) then
         !   status_ierr =  c_mpi_status_c2f(c_status, status)
         end if
-    
+
         if (present(ierror)) then
           ierror = local_ierr
         else if (local_ierr /= MPI_SUCCESS) then
           print *, "MPI_Recv failed with error code: ", local_ierr
         end if
-    
+
       end subroutine MPI_Recv_StatusIgnore_proc
 
     subroutine MPI_Waitall_proc(count, array_of_requests, array_of_statuses, ierror)
@@ -683,7 +689,7 @@ subroutine MPI_Ssend_proc(buf, count, datatype, dest, tag, comm, ierror)
         integer, intent(in) :: datatype
         integer, intent(in) :: comm
         integer, optional, intent(out) :: ierror
-        type(c_ptr) :: c_datatype, c_comm
+        integer(kind=8) :: c_datatype, c_comm
         integer :: local_ierr
 
         c_datatype = c_mpi_datatype_f2c(datatype)
@@ -700,8 +706,8 @@ subroutine MPI_Cart_create_proc(comm_old, ndims, dims, periods, reorder, comm_ca
         integer, intent(out) :: comm_cart
         integer, optional, intent(out) :: ierror
         integer(c_int) :: ndims_c, reorder_c, dims_c(ndims), periods_c(ndims)
-        type(c_ptr) :: c_comm_old
-        type(c_ptr) :: c_comm_cart
+        integer(kind=8) :: c_comm_old
+        integer(kind=8) :: c_comm_cart
         integer(c_int) :: local_ierr
 
         c_comm_old = c_mpi_comm_f2c(comm_old)
@@ -736,7 +742,7 @@ subroutine MPI_Cart_coords_proc(comm, rank, maxdims, coords, ierror)
         integer, intent(in) :: rank, maxdims
         integer, intent(out) :: coords(maxdims)
         integer, optional, intent(out) :: ierror
-        type(c_ptr) :: c_comm
+        integer(kind=8) :: c_comm
         integer(c_int) :: local_ierr
 
         c_comm = c_mpi_comm_f2c(comm)
@@ -758,7 +764,7 @@ subroutine MPI_Cart_shift_proc(comm, direction, disp, rank_source, rank_dest, ie
         integer, intent(in) :: direction, disp
         integer, intent(out) :: rank_source, rank_dest
         integer, optional, intent(out) :: ierror
-        type(c_ptr) :: c_comm
+        integer(kind=8) :: c_comm
         integer(c_int) :: local_ierr
 
         c_comm = c_mpi_comm_f2c(comm)
@@ -799,7 +805,7 @@ subroutine MPI_Cart_sub_proc (comm, remain_dims, newcomm, ierror)
         integer, intent(out) :: newcomm
         integer, optional, intent(out) :: ierror
         integer, target :: remain_dims_i(size(remain_dims))
-        type(c_ptr) :: c_comm, c_newcomm
+        integer(kind=8) :: c_comm, c_newcomm
         integer :: local_ierr
         type(c_ptr) :: remain_dims_i_ptr
 
@@ -832,7 +838,7 @@ subroutine MPI_Reduce_scalar_int(sendbuf, recvbuf, count, datatype, op, root, co
         integer, intent(in)  :: count, datatype, op, root, comm
         integer, optional, intent(out) :: ierror
 
-        type(c_ptr)    :: c_comm, c_dtype, c_op
+        integer(kind=8)    :: c_comm, c_dtype, c_op
         type(c_ptr)    :: c_sendbuf, c_recvbuf
         integer(c_int) :: local_ierr
 
diff --git a/src/mpi_c_bindings.f90 b/src/mpi_c_bindings.f90
index 1fc55c2..1f46383 100644
--- a/src/mpi_c_bindings.f90
+++ b/src/mpi_c_bindings.f90
@@ -5,31 +5,31 @@ module mpi_c_bindings
         function c_mpi_comm_f2c(comm_f) bind(C, name="get_c_comm_from_fortran")
             use iso_c_binding, only: c_int, c_ptr
             integer(c_int), value :: comm_f
-            type(c_ptr) :: c_mpi_comm_f2c  ! MPI_Comm as pointer
+            integer(kind=8) :: c_mpi_comm_f2c
         end function c_mpi_comm_f2c
 
         function c_mpi_comm_c2f(comm_c) bind(C, name="MPI_Comm_c2f")
             use iso_c_binding, only: c_int, c_ptr
-            type(c_ptr), value :: comm_c
+            integer(kind=8), value :: comm_c
             integer(c_int) :: c_mpi_comm_c2f
         end function
 
         function c_mpi_request_c2f(request) bind(C, name="MPI_Request_c2f")
             use iso_c_binding, only: c_int, c_ptr
-            type(c_ptr), value :: request
+            integer(kind=8), value :: request
             integer(c_int) :: c_mpi_request_c2f
         end function
 
         function c_mpi_datatype_f2c(datatype) bind(C, name="get_c_datatype_from_fortran")
             use iso_c_binding, only: c_int, c_ptr
             integer(c_int), value :: datatype
-            type(c_ptr) :: c_mpi_datatype_f2c
+            integer(kind=8) :: c_mpi_datatype_f2c
         end function c_mpi_datatype_f2c
 
         function c_mpi_op_f2c(op_f) bind(C, name="get_c_op_from_fortran")
             use iso_c_binding, only: c_ptr, c_int
             integer(c_int), value :: op_f
-            type(c_ptr)           :: c_mpi_op_f2c
+            integer(kind=8) :: c_mpi_op_f2c
         end function c_mpi_op_f2c
 
         function c_mpi_status_c2f(c_status, f_status) bind(C, name="MPI_Status_c2f")
@@ -38,10 +38,11 @@ function c_mpi_status_c2f(c_status, f_status) bind(C, name="MPI_Status_c2f")
             integer(c_int) :: f_status(*)  ! assumed-size array
             integer(c_int) :: c_mpi_status_c2f
         end function c_mpi_status_c2f
+
         function c_mpi_info_f2c(info_f) bind(C, name="get_c_info_from_fortran")
             use iso_c_binding, only: c_int, c_ptr
             integer(c_int), value :: info_f
-            type(c_ptr) :: c_mpi_info_f2c
+            integer(kind=8) :: c_mpi_info_f2c
         end function c_mpi_info_f2c
 
         function c_mpi_in_place_f2c(in_place_f) bind(C,name="get_c_mpi_inplace_from_fortran")
@@ -75,7 +76,7 @@ end function c_mpi_finalize
 
         function c_mpi_comm_size(comm, size) bind(C, name="MPI_Comm_size")
             use iso_c_binding, only: c_int, c_ptr
-            type(c_ptr), value :: comm
+            integer(kind=8), value :: comm
             integer(c_int), intent(out) :: size
             integer(c_int) :: c_mpi_comm_size
         end function c_mpi_comm_size
@@ -84,9 +85,9 @@ function c_mpi_bcast(buffer, count, datatype, root, comm) bind(C, name="MPI_Bcas
             use iso_c_binding, only : c_ptr, c_int
             type(c_ptr), value :: buffer
             integer(c_int), value :: count
-            type(c_ptr), value :: datatype
+            integer(kind=8), value :: datatype
             integer(c_int), value :: root
-            type(c_ptr), value :: comm
+            integer(kind=8), value :: comm
             integer(c_int) :: c_mpi_bcast
         end function c_mpi_bcast
 
@@ -96,8 +97,8 @@ function c_mpi_allgather_int(sendbuf, sendcount, sendtype, recvbuf, &
             type(c_ptr), value :: sendbuf
             type(c_ptr), value :: recvbuf
             integer(c_int), value :: sendcount, recvcount
-            type(c_ptr), value :: sendtype, recvtype
-            type(c_ptr), value :: comm
+            integer(kind=8), value :: sendtype, recvtype
+            integer(kind=8), value :: comm
             integer(c_int) :: c_mpi_allgather_int
         end function
 
@@ -107,8 +108,8 @@ function c_mpi_allgather_real(sendbuf, sendcount, sendtype, recvbuf, &
             type(c_ptr), value :: sendbuf
             type(c_ptr), value :: recvbuf
             integer(c_int), value :: sendcount, recvcount
-            type(c_ptr), value :: sendtype, recvtype
-            type(c_ptr), value :: comm
+            integer(kind=8), value :: sendtype, recvtype
+            integer(kind=8), value :: comm
             integer(c_int) :: c_mpi_allgather_real
         end function
 
@@ -116,9 +117,9 @@ function c_mpi_isend(buf, count, datatype, dest, tag, comm, request) bind(C, nam
             use iso_c_binding, only: c_int, c_double, c_ptr
             type(c_ptr), value :: buf
             integer(c_int), value :: count, dest, tag
-            type(c_ptr), value :: datatype
-            type(c_ptr), value :: comm
-            type(c_ptr), intent(out) :: request
+            integer(kind=8), value :: datatype
+            integer(kind=8), value :: comm
+            integer(kind=8), intent(out) :: request
             integer(c_int) :: c_mpi_isend
         end function
 
@@ -126,9 +127,9 @@ function c_mpi_irecv(buf, count, datatype, source, tag, comm, request) bind(C, n
             use iso_c_binding, only: c_int, c_double, c_ptr
             real(c_double), dimension(*), intent(out) :: buf
             integer(c_int), value :: count, source, tag
-            type(c_ptr), value :: datatype
-            type(c_ptr), value :: comm
-            type(c_ptr), intent(out) :: request
+           integer(kind=8), value :: datatype
+           integer(kind=8), value :: comm
+           integer(kind=8), intent(out) :: request
             integer(c_int) :: c_mpi_irecv
         end function
 
@@ -138,7 +139,7 @@ function c_mpi_allreduce(sendbuf, recvbuf, count, datatype, op, comm) &
             type(c_ptr), value :: sendbuf
             type(c_ptr), value :: recvbuf
             integer(c_int), value :: count
-            type(c_ptr), value :: datatype, op, comm
+            integer(kind=8), value :: datatype, op, comm
             integer(c_int) :: c_mpi_allreduce
         end function
 
@@ -149,36 +150,36 @@ function c_mpi_wtime() result(time) bind(C, name="MPI_Wtime")
 
         function c_mpi_barrier(comm) bind(C, name="MPI_Barrier")
             use iso_c_binding, only: c_ptr, c_int
-            type(c_ptr), value :: comm      ! MPI_Comm as pointer
+            integer(kind=8), value :: comm      ! MPI_Comm as pointer
             integer(c_int) :: c_mpi_barrier
         end function c_mpi_barrier
 
         function c_mpi_comm_rank(comm, rank) bind(C, name="MPI_Comm_rank")
             use iso_c_binding, only: c_int, c_ptr
-            type(c_ptr), value :: comm
+            integer(kind=8), value :: comm
             integer(c_int), intent(out) :: rank
             integer(c_int) :: c_mpi_comm_rank
         end function c_mpi_comm_rank
 
         function c_mpi_comm_split_type(c_comm, split_type, key, c_info, new_comm) bind(C, name="MPI_Comm_split_type")
             use iso_c_binding, only: c_ptr, c_int
-            type(c_ptr), value :: c_comm 
+            integer(kind=8), value :: c_comm 
             integer(c_int), value :: split_type
             integer(c_int), value :: key
-            type(c_ptr), value :: c_info
-            type(c_ptr) :: new_comm
+            integer(kind=8), value :: c_info
+            integer(kind=8) :: new_comm
             integer(c_int) :: c_mpi_comm_split_type
         end function c_mpi_comm_split_type
 
         function c_mpi_recv(buf, count, c_dtype, source, tag, c_comm, status) bind(C, name="MPI_Recv")
             use iso_c_binding, only: c_ptr, c_int, c_double
-            real(c_double), dimension(*), intent(out) :: buf
+            type(c_ptr), value :: buf
             integer(c_int), value :: count
-            type(c_ptr), value :: c_dtype
+            integer(kind=8), value :: c_dtype
             integer(c_int), value :: source
             integer(c_int), value :: tag
-            type(c_ptr), value :: c_comm
-            type(c_ptr) :: status
+            integer(kind=8), value :: c_comm
+            type(c_ptr), value :: status
             integer(c_int) :: c_mpi_recv
         end function c_mpi_recv
 
@@ -194,23 +195,23 @@ function c_mpi_ssend(buf, count, datatype, dest, tag, comm) bind(C, name="MPI_Ss
             use iso_c_binding, only: c_int, c_double, c_ptr
             real(c_double), dimension(*), intent(in) :: buf
             integer(c_int), value :: count, dest, tag
-            type(c_ptr), value :: datatype
-            type(c_ptr), value :: comm
+            integer(kind=8), value :: datatype
+            integer(kind=8), value :: comm
             integer(c_int) :: c_mpi_ssend
         end function
 
         function c_mpi_cart_create(comm_old, ndims, dims, periods, reorder, comm_cart) bind(C, name="MPI_Cart_create")
             use iso_c_binding, only: c_int, c_ptr
-            type(c_ptr), value :: comm_old
+            integer(kind=8), value :: comm_old
             integer(c_int), value :: ndims, reorder
             integer(c_int), intent(in) :: dims(*), periods(*)
-            type(c_ptr), intent(out) :: comm_cart
+            integer(kind=8), intent(out) :: comm_cart
             integer(c_int) :: c_mpi_cart_create
         end function
 
         function c_mpi_cart_coords(comm, rank, maxdims, coords) bind(C, name="MPI_Cart_coords")
             use iso_c_binding,  only: c_int, c_ptr
-            type(c_ptr), value :: comm
+            integer(kind=8), value :: comm
             integer(c_int), value :: rank, maxdims
             integer(c_int), intent(out) :: coords(*)
             integer(c_int) :: c_mpi_cart_coords
@@ -218,7 +219,7 @@ function c_mpi_cart_coords(comm, rank, maxdims, coords) bind(C, name="MPI_Cart_c
 
         function c_mpi_cart_shift(comm, direction, disp, rank_source, rank_dest) bind(C, name="MPI_Cart_shift")
             use iso_c_binding, only: c_int, c_ptr
-            type(c_ptr), value :: comm
+            integer(kind=8), value :: comm
             integer(c_int), value :: direction, disp
             integer(c_int), intent(out) :: rank_source, rank_dest
             integer(c_int) :: c_mpi_cart_shift
@@ -233,9 +234,9 @@ function c_mpi_dims_create(nnodes, ndims, dims) bind(C, name="MPI_Dims_create")
 
         function c_mpi_cart_sub(comm, remain_dims, newcomm) bind(C, name ="MPI_Cart_sub")
             use iso_c_binding, only: c_int, c_ptr
-            type(c_ptr), value :: comm
+            integer(kind=8), value :: comm
             type(c_ptr), value :: remain_dims
-            type(c_ptr), intent(out) :: newcomm
+            integer(kind=8), intent(out) :: newcomm
             integer(c_int) :: c_mpi_cart_sub
         end function
 
@@ -246,10 +247,10 @@ function c_mpi_reduce(sendbuf, recvbuf, count, c_dtype, c_op, root, c_comm) &
             type(c_ptr), value :: sendbuf
             type(c_ptr), value :: recvbuf
             integer(c_int), value :: count
-            type(c_ptr), value :: c_dtype
-            type(c_ptr), value :: c_op 
+            integer(kind=8), value :: c_dtype
+            integer(kind=8), value :: c_op 
             integer(c_int), value :: root
-            type(c_ptr), value :: c_comm
+            integer(kind=8), value :: c_comm
            integer(c_int) :: c_mpi_reduce
         end function c_mpi_reduce
 

From 168f2a959db4f132dae5d256daf949b64680eeaf Mon Sep 17 00:00:00 2001
From: Gaurav Dhingra <gauravdhingra.gxyd@gmail.com>
Date: Thu, 10 Apr 2025 14:46:57 +0530
Subject: [PATCH 2/3] use MPI_HANDLE_KIND as preprocessor directive for Open
 MPI and MPICH

---
 .github/workflows/CI.yml | 32 ++++++++--------
 src/mpi.f90              | 63 ++++++++++++++++--------------
 src/mpi_c_bindings.f90   | 82 +++++++++++++++++++++-------------------
 tests/run_tests.sh       | 10 ++++-
 4 files changed, 103 insertions(+), 84 deletions(-)

diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index a271887..320b514 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -73,8 +73,8 @@ jobs:
         shell: bash -e -x -l {0}
         run: |
           cd tests
-          FC="gfortran" ./run_tests.sh
-          FC="gfortran -O3 -march=native" ./run_tests.sh
+          FC="gfortran -cpp" ./run_tests.sh
+          FC="gfortran -O3 -march=native -cpp" ./run_tests.sh
 
   Run_standalone_tests_with_GFortran_with_MPICH:
     name: "Run standalone tests with GFortran with MPICH"
@@ -95,8 +95,8 @@ jobs:
         shell: bash -e -x -l {0}
         run: |
           cd tests
-          FC="gfortran" ./run_tests.sh
-          FC="gfortran -O3 -march=native" ./run_tests.sh
+          FC="gfortran -cpp" ./run_tests.sh
+          FC="gfortran -O3 -march=native -cpp" ./run_tests.sh
 
   Run_standalone_tests_with_LFortran_with_OpenMPI:
     name: "Run standalone tests with LFortran with Open MPI"
@@ -117,8 +117,8 @@ jobs:
         shell: bash -e -x -l {0}
         run: |
           cd tests
-          FC="lfortran" ./run_tests.sh
-          FC="lfortran --fast" ./run_tests.sh
+          FC="lfortran --cpp" ./run_tests.sh
+          FC="lfortran --fast --cpp" ./run_tests.sh
 
   Run_standalone_tests_with_LFortran_with_MPICH:
     name: "Run standalone tests with LFortran with MPICH"
@@ -139,8 +139,8 @@ jobs:
         shell: bash -e -x -l {0}
         run: |
           cd tests
-          FC="lfortran" ./run_tests.sh
-          FC="lfortran --fast" ./run_tests.sh
+          FC="lfortran --cpp" ./run_tests.sh
+          FC="lfortran --fast --cpp" ./run_tests.sh
 
   Compile_POT3D_with_GFortran_with_OpenMPI:
     name: "Build POT3D and validate with GFortran with Open MPI"
@@ -162,14 +162,14 @@ jobs:
         shell: bash -e -x -l {0}
         run: |
           cd tests/pot3d
-          FC="gfortran -O3 -march=native" ./build_and_run_gfortran.sh
+          FC="gfortran -O3 -march=native -cpp" ./build_and_run_gfortran.sh
 
       # build and validation without GFortran's optimization
       - name: POT3D Build and validation with GFortran without optimization using Open MPI (MPI only)
         shell: bash -e -x -l {0}
         run: |
           cd tests/pot3d
-          FC="gfortran" ./build_and_run_gfortran.sh
+          FC="gfortran -cpp" ./build_and_run_gfortran.sh
 
   Compile_POT3D_with_LFortran_with_OpenMPI:
     name: "Build POT3D and validate with LFortran with Open MPI"
@@ -191,14 +191,14 @@ jobs:
         shell: bash -e -x -l {0}
         run: |
           cd tests/pot3d
-          FC="lfortran --fast" ./build_and_run_lfortran.sh
+          FC="lfortran --fast --cpp" ./build_and_run_lfortran.sh
 
       # build and validation without LFortran's optimization
       - name: POT3D Build and validation with LFortran without optimization using Open MPI (MPI only)
         shell: bash -e -x -l {0}
         run: |
           cd tests/pot3d
-          FC="lfortran" ./build_and_run_lfortran.sh
+          FC="lfortran --cpp" ./build_and_run_lfortran.sh
 
   Compile_POT3D_with_GFortran_with_MPICH:
     name: "Build POT3D and validate with GFortran with MPICH"
@@ -220,14 +220,14 @@ jobs:
         shell: bash -e -x -l {0}
         run: |
           cd tests/pot3d
-          FC="gfortran -O3 -march=native" ./build_and_run_gfortran.sh
+          FC="gfortran -O3 -march=native -cpp" ./build_and_run_gfortran.sh
 
       # build and validation without GFortran's optimization
       - name: POT3D Build and validation with GFortran without optimization (MPI only)
         shell: bash -e -x -l {0}
         run: |
           cd tests/pot3d
-          FC="gfortran" ./build_and_run_gfortran.sh
+          FC="gfortran -cpp" ./build_and_run_gfortran.sh
 
   Compile_POT3D_with_LFortran_with_MPICH:
     name: "Build POT3D and validate with LFortran with MPICH"
@@ -249,11 +249,11 @@ jobs:
         shell: bash -e -x -l {0}
         run: |
           cd tests/pot3d
-          FC="lfortran --fast" ./build_and_run_lfortran.sh
+          FC="lfortran --fast --cpp" ./build_and_run_lfortran.sh
 
       # build and validation without LFortran's optimization
       - name: POT3D Build and validation with LFortran without optimization using MPICH (MPI only)
         shell: bash -e -x -l {0}
         run: |
           cd tests/pot3d
-          FC="lfortran" ./build_and_run_lfortran.sh
+          FC="lfortran --cpp" ./build_and_run_lfortran.sh
diff --git a/src/mpi.f90 b/src/mpi.f90
index 6d27b27..7fdcf54 100644
--- a/src/mpi.f90
+++ b/src/mpi.f90
@@ -1,5 +1,12 @@
 module mpi
     implicit none
+
+#ifdef OPEN_MPI
+#define MPI_HANDLE_KIND 8
+#else
+#define MPI_HANDLE_KIND 4
+#endif
+
     integer, parameter :: MPI_THREAD_FUNNELED = 1
 
     integer, parameter :: MPI_INTEGER = -10002
@@ -189,7 +196,7 @@ subroutine MPI_Comm_size_proc(comm, size, ierror)
         integer, intent(out) :: size
         integer, optional, intent(out) :: ierror
         integer :: local_ierr
-        integer(kind=8) :: c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_comm
 
         c_comm = c_mpi_comm_f2c(comm)
         local_ierr = c_mpi_comm_size(c_comm, size)
@@ -210,7 +217,7 @@ subroutine MPI_Bcast_int_scalar(buffer, count, datatype, root, comm, ierror)
         integer, intent(in) :: datatype
         integer, intent(in) :: comm
         integer, optional, intent(out) :: ierror
-        integer(kind=8) :: c_comm, c_datatype
+        integer(kind=MPI_HANDLE_KIND) :: c_comm, c_datatype
         integer :: local_ierr
         type(c_ptr) :: buffer_ptr
 
@@ -236,7 +243,7 @@ subroutine MPI_Bcast_real_2D(buffer, count, datatype, root, comm, ierror)
         integer, intent(in) :: datatype
         integer, intent(in) :: comm
         integer, optional, intent(out) :: ierror
-        integer(kind=8) :: c_comm, c_datatype
+        integer(kind=MPI_HANDLE_KIND) :: c_comm, c_datatype
         integer :: local_ierr
         type(c_ptr) :: buffer_ptr
 
@@ -263,9 +270,9 @@ subroutine MPI_Allgather_int(sendbuf, sendcount, sendtype, recvbuf, recvcount, r
         integer, intent(in) :: sendtype, recvtype
         integer, intent(in) :: comm
         integer, optional, intent(out) :: ierror
-        integer(kind=8) :: c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_comm
         integer(c_int) :: local_ierr
-        integer(kind=8) :: c_sendtype, c_recvtype
+        integer(kind=MPI_HANDLE_KIND) :: c_sendtype, c_recvtype
         type(c_ptr) :: sendbuf_ptr, recvbuf_ptr
 
         c_comm = c_mpi_comm_f2c(comm)
@@ -293,9 +300,9 @@ subroutine MPI_Allgather_real(sendbuf, sendcount, sendtype, recvbuf, recvcount,
         integer, intent(in) :: sendtype, recvtype
         integer, intent(in) :: comm
         integer, optional, intent(out) :: ierror
-        integer(kind=8) :: c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_comm
         integer(c_int) :: local_ierr
-        integer(kind=8) :: c_sendtype, c_recvtype
+        integer(kind=MPI_HANDLE_KIND) :: c_sendtype, c_recvtype
         type(c_ptr) :: sendbuf_ptr, recvbuf_ptr
 
         c_comm = c_mpi_comm_f2c(comm)
@@ -324,7 +331,7 @@ subroutine MPI_Isend_2d(buf, count, datatype, dest, tag, comm, request, ierror)
         integer, intent(out) :: request
         integer, optional, intent(out) :: ierror
         type(c_ptr) :: buf_ptr
-        integer(kind=8) :: c_datatype, c_comm, c_request
+        integer(kind=MPI_HANDLE_KIND) :: c_datatype, c_comm, c_request
         integer(c_int) :: local_ierr
 
         buf_ptr = c_loc(buf)
@@ -353,7 +360,7 @@ subroutine MPI_Isend_3d(buf, count, datatype, dest, tag, comm, request, ierror)
         integer, intent(out) :: request
         integer, optional, intent(out) :: ierror
         type(c_ptr) :: buf_ptr
-        integer(kind=8) :: c_datatype, c_comm, c_request
+        integer(kind=MPI_HANDLE_KIND) :: c_datatype, c_comm, c_request
         integer(c_int) :: local_ierr
 
         buf_ptr = c_loc(buf)
@@ -381,10 +388,10 @@ subroutine MPI_Irecv_proc(buf, count, datatype, source, tag, comm, request, ierr
         integer, intent(in) :: comm
         integer, intent(out) :: request
         integer, optional, intent(out) :: ierror
-        integer(kind=8) :: c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_comm
         integer(c_int) :: local_ierr
-        integer(kind=8) :: c_datatype
-        integer(kind=8) :: c_request
+        integer(kind=MPI_HANDLE_KIND) :: c_datatype
+        integer(kind=MPI_HANDLE_KIND) :: c_request
 
         c_comm = c_mpi_comm_f2c(comm)
         c_datatype = c_mpi_datatype_f2c(datatype)
@@ -408,7 +415,7 @@ subroutine MPI_Allreduce_scalar(sendbuf, recvbuf, count, datatype, op, comm, ier
         integer, intent(in) :: count, datatype, op, comm
         integer, intent(out), optional :: ierror
         type(c_ptr) :: sendbuf_ptr, recvbuf_ptr
-        integer(kind=8) :: c_datatype, c_op, c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_datatype, c_op, c_comm
         integer(c_int) :: local_ierr
 
         if (sendbuf == MPI_IN_PLACE) then
@@ -440,7 +447,7 @@ subroutine MPI_Allreduce_1D_recv_proc(sendbuf, recvbuf, count, datatype, op, com
         integer, intent(in) :: count, datatype, op, comm
         integer, intent(out), optional :: ierror
         type(c_ptr) :: sendbuf_ptr, recvbuf_ptr
-        integer(kind=8) :: c_datatype, c_op, c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_datatype, c_op, c_comm
         integer(c_int) :: local_ierr
 
         if (sendbuf == MPI_IN_PLACE) then
@@ -472,7 +479,7 @@ subroutine MPI_Allreduce_1D_real_proc(sendbuf, recvbuf, count, datatype, op, com
         integer, intent(in) :: count, datatype, op, comm
         integer, intent(out), optional :: ierror
         type(c_ptr) :: sendbuf_ptr, recvbuf_ptr
-        integer(kind=8) :: c_datatype, c_op, c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_datatype, c_op, c_comm
         integer(c_int) :: local_ierr
 
         sendbuf_ptr = c_loc(sendbuf)
@@ -500,7 +507,7 @@ subroutine MPI_Allreduce_1D_int_proc(sendbuf, recvbuf, count, datatype, op, comm
         integer, intent(in) :: count, datatype, op, comm
         integer, intent(out), optional :: ierror
         type(c_ptr) :: sendbuf_ptr, recvbuf_ptr
-        integer(kind=8) :: c_datatype, c_op, c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_datatype, c_op, c_comm
         integer(c_int) :: local_ierr
 
         sendbuf_ptr = c_loc(sendbuf)
@@ -531,7 +538,7 @@ subroutine MPI_Barrier_proc(comm, ierror)
         use iso_c_binding, only: c_int, c_ptr
         integer, intent(in) :: comm
         integer, intent(out), optional :: ierror
-        integer(kind=8) :: c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_comm
         integer(c_int) :: local_ierr
 
         ! Convert Fortran handle to C handle
@@ -553,7 +560,7 @@ subroutine MPI_Comm_rank_proc(comm, rank, ierror)
         integer, intent(in) :: comm
         integer, intent(out) :: rank
         integer, optional, intent(out) :: ierror
-        integer(kind=8) :: c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_comm
         integer(c_int) :: local_ierr
 
         c_comm = c_mpi_comm_f2c(comm)
@@ -578,7 +585,7 @@ subroutine MPI_Comm_split_type_proc(comm, split_type, key, info, newcomm, ierror
         integer, optional, intent(out) :: ierror
     
         integer(c_int) :: local_ierr
-        integer(kind=8) :: c_comm, c_info, c_new_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_comm, c_info, c_new_comm
     
         ! Convert Fortran communicator and info handles to C pointers.
         c_comm = c_mpi_comm_f2c(comm)
@@ -609,7 +616,7 @@ subroutine MPI_Recv_StatusArray_proc(buf, count, datatype, source, tag, comm, st
         integer, optional, intent(out) :: ierror
     
         integer(c_int) :: local_ierr, status_ierr
-        integer(kind=8) :: c_dtype, c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_dtype, c_comm
         type(c_ptr) :: c_status
         integer(c_int), dimension(MPI_STATUS_SIZE), target :: tmp_status
     
@@ -645,7 +652,7 @@ subroutine MPI_Recv_StatusIgnore_proc(buf, count, datatype, source, tag, comm, s
         integer, optional, intent(out) :: ierror
     
         integer(c_int) :: local_ierr, status_ierr
-        integer(kind=8) :: c_dtype, c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_dtype, c_comm
         type(c_ptr) :: c_status
         integer(c_int), dimension(MPI_STATUS_SIZE), target :: tmp_status
 
@@ -689,7 +696,7 @@ subroutine MPI_Ssend_proc(buf, count, datatype, dest, tag, comm, ierror)
         integer, intent(in) :: datatype
         integer, intent(in) :: comm
         integer, optional, intent(out) :: ierror
-        integer(kind=8) :: c_datatype, c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_datatype, c_comm
         integer :: local_ierr
 
         c_datatype = c_mpi_datatype_f2c(datatype)
@@ -706,8 +713,8 @@ subroutine MPI_Cart_create_proc(comm_old, ndims, dims, periods, reorder, comm_ca
         integer, intent(out) :: comm_cart
         integer, optional, intent(out) :: ierror
         integer(c_int) :: ndims_c, reorder_c, dims_c(ndims), periods_c(ndims)
-        integer(kind=8) :: c_comm_old
-        integer(kind=8) :: c_comm_cart
+        integer(kind=MPI_HANDLE_KIND) :: c_comm_old
+        integer(kind=MPI_HANDLE_KIND) :: c_comm_cart
         integer(c_int) :: local_ierr
 
         c_comm_old = c_mpi_comm_f2c(comm_old)
@@ -742,7 +749,7 @@ subroutine MPI_Cart_coords_proc(comm, rank, maxdims, coords, ierror)
         integer, intent(in) :: rank, maxdims
         integer, intent(out) :: coords(maxdims)
         integer, optional, intent(out) :: ierror
-        integer(kind=8) :: c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_comm
         integer(c_int) :: local_ierr
 
         c_comm = c_mpi_comm_f2c(comm)
@@ -764,7 +771,7 @@ subroutine MPI_Cart_shift_proc(comm, direction, disp, rank_source, rank_dest, ie
         integer, intent(in) :: direction, disp
         integer, intent(out) :: rank_source, rank_dest
         integer, optional, intent(out) :: ierror
-        integer(kind=8) :: c_comm
+        integer(kind=MPI_HANDLE_KIND) :: c_comm
         integer(c_int) :: local_ierr
 
         c_comm = c_mpi_comm_f2c(comm)
@@ -805,7 +812,7 @@ subroutine MPI_Cart_sub_proc (comm, remain_dims, newcomm, ierror)
         integer, intent(out) :: newcomm
         integer, optional, intent(out) :: ierror
         integer, target :: remain_dims_i(size(remain_dims))
-        integer(kind=8) :: c_comm, c_newcomm
+        integer(kind=MPI_HANDLE_KIND) :: c_comm, c_newcomm
         integer :: local_ierr
         type(c_ptr) :: remain_dims_i_ptr
 
@@ -838,7 +845,7 @@ subroutine MPI_Reduce_scalar_int(sendbuf, recvbuf, count, datatype, op, root, co
         integer, intent(in)  :: count, datatype, op, root, comm
         integer, optional, intent(out) :: ierror
 
-        integer(kind=8)    :: c_comm, c_dtype, c_op
+        integer(kind=MPI_HANDLE_KIND)    :: c_comm, c_dtype, c_op
         type(c_ptr)    :: c_sendbuf, c_recvbuf
         integer(c_int) :: local_ierr
 
diff --git a/src/mpi_c_bindings.f90 b/src/mpi_c_bindings.f90
index 1f46383..c81e85f 100644
--- a/src/mpi_c_bindings.f90
+++ b/src/mpi_c_bindings.f90
@@ -1,35 +1,41 @@
 module mpi_c_bindings
     implicit none
 
+#ifdef OPEN_MPI
+#define MPI_HANDLE_KIND 8
+#else
+#define MPI_HANDLE_KIND 4
+#endif
+
     interface
         function c_mpi_comm_f2c(comm_f) bind(C, name="get_c_comm_from_fortran")
             use iso_c_binding, only: c_int, c_ptr
             integer(c_int), value :: comm_f
-            integer(kind=8) :: c_mpi_comm_f2c
+            integer(kind=MPI_HANDLE_KIND) :: c_mpi_comm_f2c
         end function c_mpi_comm_f2c
 
         function c_mpi_comm_c2f(comm_c) bind(C, name="MPI_Comm_c2f")
             use iso_c_binding, only: c_int, c_ptr
-            integer(kind=8), value :: comm_c
+            integer(kind=MPI_HANDLE_KIND), value :: comm_c
             integer(c_int) :: c_mpi_comm_c2f
         end function
 
         function c_mpi_request_c2f(request) bind(C, name="MPI_Request_c2f")
             use iso_c_binding, only: c_int, c_ptr
-            integer(kind=8), value :: request
+            integer(kind=MPI_HANDLE_KIND), value :: request
             integer(c_int) :: c_mpi_request_c2f
         end function
 
         function c_mpi_datatype_f2c(datatype) bind(C, name="get_c_datatype_from_fortran")
             use iso_c_binding, only: c_int, c_ptr
             integer(c_int), value :: datatype
-            integer(kind=8) :: c_mpi_datatype_f2c
+            integer(kind=MPI_HANDLE_KIND) :: c_mpi_datatype_f2c
         end function c_mpi_datatype_f2c
 
         function c_mpi_op_f2c(op_f) bind(C, name="get_c_op_from_fortran")
             use iso_c_binding, only: c_ptr, c_int
             integer(c_int), value :: op_f
-            integer(kind=8) :: c_mpi_op_f2c
+            integer(kind=MPI_HANDLE_KIND) :: c_mpi_op_f2c
         end function c_mpi_op_f2c
 
         function c_mpi_status_c2f(c_status, f_status) bind(C, name="MPI_Status_c2f")
@@ -42,7 +48,7 @@ end function c_mpi_status_c2f
         function c_mpi_info_f2c(info_f) bind(C, name="get_c_info_from_fortran")
             use iso_c_binding, only: c_int, c_ptr
             integer(c_int), value :: info_f
-            integer(kind=8) :: c_mpi_info_f2c
+            integer(kind=MPI_HANDLE_KIND) :: c_mpi_info_f2c
         end function c_mpi_info_f2c
 
         function c_mpi_in_place_f2c(in_place_f) bind(C,name="get_c_mpi_inplace_from_fortran")
@@ -76,7 +82,7 @@ end function c_mpi_finalize
 
         function c_mpi_comm_size(comm, size) bind(C, name="MPI_Comm_size")
             use iso_c_binding, only: c_int, c_ptr
-            integer(kind=8), value :: comm
+            integer(kind=MPI_HANDLE_KIND), value :: comm
             integer(c_int), intent(out) :: size
             integer(c_int) :: c_mpi_comm_size
         end function c_mpi_comm_size
@@ -85,9 +91,9 @@ function c_mpi_bcast(buffer, count, datatype, root, comm) bind(C, name="MPI_Bcas
             use iso_c_binding, only : c_ptr, c_int
             type(c_ptr), value :: buffer
             integer(c_int), value :: count
-            integer(kind=8), value :: datatype
+            integer(kind=MPI_HANDLE_KIND), value :: datatype
             integer(c_int), value :: root
-            integer(kind=8), value :: comm
+            integer(kind=MPI_HANDLE_KIND), value :: comm
             integer(c_int) :: c_mpi_bcast
         end function c_mpi_bcast
 
@@ -97,8 +103,8 @@ function c_mpi_allgather_int(sendbuf, sendcount, sendtype, recvbuf, &
             type(c_ptr), value :: sendbuf
             type(c_ptr), value :: recvbuf
             integer(c_int), value :: sendcount, recvcount
-            integer(kind=8), value :: sendtype, recvtype
-            integer(kind=8), value :: comm
+            integer(kind=MPI_HANDLE_KIND), value :: sendtype, recvtype
+            integer(kind=MPI_HANDLE_KIND), value :: comm
             integer(c_int) :: c_mpi_allgather_int
         end function
 
@@ -108,8 +114,8 @@ function c_mpi_allgather_real(sendbuf, sendcount, sendtype, recvbuf, &
             type(c_ptr), value :: sendbuf
             type(c_ptr), value :: recvbuf
             integer(c_int), value :: sendcount, recvcount
-            integer(kind=8), value :: sendtype, recvtype
-            integer(kind=8), value :: comm
+            integer(kind=MPI_HANDLE_KIND), value :: sendtype, recvtype
+            integer(kind=MPI_HANDLE_KIND), value :: comm
             integer(c_int) :: c_mpi_allgather_real
         end function
 
@@ -117,9 +123,9 @@ function c_mpi_isend(buf, count, datatype, dest, tag, comm, request) bind(C, nam
             use iso_c_binding, only: c_int, c_double, c_ptr
             type(c_ptr), value :: buf
             integer(c_int), value :: count, dest, tag
-            integer(kind=8), value :: datatype
-            integer(kind=8), value :: comm
-            integer(kind=8), intent(out) :: request
+            integer(kind=MPI_HANDLE_KIND), value :: datatype
+            integer(kind=MPI_HANDLE_KIND), value :: comm
+            integer(kind=MPI_HANDLE_KIND), intent(out) :: request
             integer(c_int) :: c_mpi_isend
         end function
 
@@ -127,9 +133,9 @@ function c_mpi_irecv(buf, count, datatype, source, tag, comm, request) bind(C, n
             use iso_c_binding, only: c_int, c_double, c_ptr
             real(c_double), dimension(*), intent(out) :: buf
             integer(c_int), value :: count, source, tag
-           integer(kind=8), value :: datatype
-           integer(kind=8), value :: comm
-           integer(kind=8), intent(out) :: request
+           integer(kind=MPI_HANDLE_KIND), value :: datatype
+           integer(kind=MPI_HANDLE_KIND), value :: comm
+           integer(kind=MPI_HANDLE_KIND), intent(out) :: request
             integer(c_int) :: c_mpi_irecv
         end function
 
@@ -139,7 +145,7 @@ function c_mpi_allreduce(sendbuf, recvbuf, count, datatype, op, comm) &
             type(c_ptr), value :: sendbuf
             type(c_ptr), value :: recvbuf
             integer(c_int), value :: count
-            integer(kind=8), value :: datatype, op, comm
+            integer(kind=MPI_HANDLE_KIND), value :: datatype, op, comm
             integer(c_int) :: c_mpi_allreduce
         end function
 
@@ -150,24 +156,24 @@ function c_mpi_wtime() result(time) bind(C, name="MPI_Wtime")
 
         function c_mpi_barrier(comm) bind(C, name="MPI_Barrier")
             use iso_c_binding, only: c_ptr, c_int
-            integer(kind=8), value :: comm      ! MPI_Comm as pointer
+            integer(kind=MPI_HANDLE_KIND), value :: comm      ! MPI_Comm as pointer
             integer(c_int) :: c_mpi_barrier
         end function c_mpi_barrier
 
         function c_mpi_comm_rank(comm, rank) bind(C, name="MPI_Comm_rank")
             use iso_c_binding, only: c_int, c_ptr
-            integer(kind=8), value :: comm
+            integer(kind=MPI_HANDLE_KIND), value :: comm
             integer(c_int), intent(out) :: rank
             integer(c_int) :: c_mpi_comm_rank
         end function c_mpi_comm_rank
 
         function c_mpi_comm_split_type(c_comm, split_type, key, c_info, new_comm) bind(C, name="MPI_Comm_split_type")
             use iso_c_binding, only: c_ptr, c_int
-            integer(kind=8), value :: c_comm 
+            integer(kind=MPI_HANDLE_KIND), value :: c_comm
             integer(c_int), value :: split_type
             integer(c_int), value :: key
-            integer(kind=8), value :: c_info
-            integer(kind=8) :: new_comm
+            integer(kind=MPI_HANDLE_KIND), value :: c_info
+            integer(kind=MPI_HANDLE_KIND) :: new_comm
             integer(c_int) :: c_mpi_comm_split_type
         end function c_mpi_comm_split_type
 
@@ -175,10 +181,10 @@ function c_mpi_recv(buf, count, c_dtype, source, tag, c_comm, status) bind(C, na
             use iso_c_binding, only: c_ptr, c_int, c_double
             type(c_ptr), value :: buf
             integer(c_int), value :: count
-            integer(kind=8), value :: c_dtype
+            integer(kind=MPI_HANDLE_KIND), value :: c_dtype
             integer(c_int), value :: source
             integer(c_int), value :: tag
-            integer(kind=8), value :: c_comm
+            integer(kind=MPI_HANDLE_KIND), value :: c_comm
             type(c_ptr), value :: status
             integer(c_int) :: c_mpi_recv
         end function c_mpi_recv
@@ -195,23 +201,23 @@ function c_mpi_ssend(buf, count, datatype, dest, tag, comm) bind(C, name="MPI_Ss
             use iso_c_binding, only: c_int, c_double, c_ptr
             real(c_double), dimension(*), intent(in) :: buf
             integer(c_int), value :: count, dest, tag
-            integer(kind=8), value :: datatype
-            integer(kind=8), value :: comm
+            integer(kind=MPI_HANDLE_KIND), value :: datatype
+            integer(kind=MPI_HANDLE_KIND), value :: comm
             integer(c_int) :: c_mpi_ssend
         end function
 
         function c_mpi_cart_create(comm_old, ndims, dims, periods, reorder, comm_cart) bind(C, name="MPI_Cart_create")
             use iso_c_binding, only: c_int, c_ptr
-            integer(kind=8), value :: comm_old
+            integer(kind=MPI_HANDLE_KIND), value :: comm_old
             integer(c_int), value :: ndims, reorder
             integer(c_int), intent(in) :: dims(*), periods(*)
-            integer(kind=8), intent(out) :: comm_cart
+            integer(kind=MPI_HANDLE_KIND), intent(out) :: comm_cart
             integer(c_int) :: c_mpi_cart_create
         end function
 
         function c_mpi_cart_coords(comm, rank, maxdims, coords) bind(C, name="MPI_Cart_coords")
             use iso_c_binding,  only: c_int, c_ptr
-            integer(kind=8), value :: comm
+            integer(kind=MPI_HANDLE_KIND), value :: comm
             integer(c_int), value :: rank, maxdims
             integer(c_int), intent(out) :: coords(*)
             integer(c_int) :: c_mpi_cart_coords
@@ -219,7 +225,7 @@ function c_mpi_cart_coords(comm, rank, maxdims, coords) bind(C, name="MPI_Cart_c
 
         function c_mpi_cart_shift(comm, direction, disp, rank_source, rank_dest) bind(C, name="MPI_Cart_shift")
             use iso_c_binding, only: c_int, c_ptr
-            integer(kind=8), value :: comm
+            integer(kind=MPI_HANDLE_KIND), value :: comm
             integer(c_int), value :: direction, disp
             integer(c_int), intent(out) :: rank_source, rank_dest
             integer(c_int) :: c_mpi_cart_shift
@@ -234,9 +240,9 @@ function c_mpi_dims_create(nnodes, ndims, dims) bind(C, name="MPI_Dims_create")
 
         function c_mpi_cart_sub(comm, remain_dims, newcomm) bind(C, name ="MPI_Cart_sub")
             use iso_c_binding, only: c_int, c_ptr
-            integer(kind=8), value :: comm
+            integer(kind=MPI_HANDLE_KIND), value :: comm
             type(c_ptr), value :: remain_dims
-            integer(kind=8), intent(out) :: newcomm
+            integer(kind=MPI_HANDLE_KIND), intent(out) :: newcomm
             integer(c_int) :: c_mpi_cart_sub
         end function
 
@@ -247,10 +253,10 @@ function c_mpi_reduce(sendbuf, recvbuf, count, c_dtype, c_op, root, c_comm) &
             type(c_ptr), value :: sendbuf
             type(c_ptr), value :: recvbuf
             integer(c_int), value :: count
-            integer(kind=8), value :: c_dtype
-            integer(kind=8), value :: c_op 
+            integer(kind=MPI_HANDLE_KIND), value :: c_dtype
+            integer(kind=MPI_HANDLE_KIND), value :: c_op
             integer(c_int), value :: root
-            integer(kind=8), value :: c_comm
+            integer(kind=MPI_HANDLE_KIND), value :: c_comm
            integer(c_int) :: c_mpi_reduce
         end function c_mpi_reduce
 
diff --git a/tests/run_tests.sh b/tests/run_tests.sh
index caf5d07..7e7feec 100755
--- a/tests/run_tests.sh
+++ b/tests/run_tests.sh
@@ -48,6 +48,12 @@ else
   fi
 fi
 
+# Define preprocessor flags based on MPI type
+FC_FLAGS=""
+if [[ "$MPI_TYPE" == "openmpi" ]]; then
+  FC_FLAGS="-DOPEN_MPI"
+fi
+
 echo -e "${RED}Removing all untracked files${NC}"
 git clean -dfx
 echo -e "#################################"
@@ -70,8 +76,8 @@ fi
 
 if [ $USE_WRAPPERS -eq 1 ]; then
   $CC -I"$CONDA_PREFIX/include" -c ../src/mpi_wrapper.c
-  $FC -c ../src/mpi_c_bindings.f90
-  $FC -c ../src/mpi.f90
+  $FC $FC_FLAGS -c ../src/mpi_c_bindings.f90
+  $FC $FC_FLAGS -c ../src/mpi.f90
 fi
 
 start_time=$(date +%s)

From ebcd827b492b5ddb5c6af6af41578168846686f5 Mon Sep 17 00:00:00 2001
From: Gaurav Dhingra <gauravdhingra.gxyd@gmail.com>
Date: Thu, 10 Apr 2025 14:59:39 +0530
Subject: [PATCH 3/3] use -DOPEN_MPI=yes when running with Open MPI

---
 .github/workflows/CI.yml | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 320b514..30bac03 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -73,8 +73,8 @@ jobs:
         shell: bash -e -x -l {0}
         run: |
           cd tests
-          FC="gfortran -cpp" ./run_tests.sh
-          FC="gfortran -O3 -march=native -cpp" ./run_tests.sh
+          FC="gfortran -cpp -DOPEN_MPI=yes" ./run_tests.sh
+          FC="gfortran -O3 -march=native -cpp -DOPEN_MPI=yes" ./run_tests.sh
 
   Run_standalone_tests_with_GFortran_with_MPICH:
     name: "Run standalone tests with GFortran with MPICH"
@@ -117,8 +117,8 @@ jobs:
         shell: bash -e -x -l {0}
         run: |
           cd tests
-          FC="lfortran --cpp" ./run_tests.sh
-          FC="lfortran --fast --cpp" ./run_tests.sh
+          FC="lfortran --cpp -DOPEN_MPI=yes" ./run_tests.sh
+          FC="lfortran --fast --cpp -DOPEN_MPI=yes" ./run_tests.sh
 
   Run_standalone_tests_with_LFortran_with_MPICH:
     name: "Run standalone tests with LFortran with MPICH"
@@ -162,14 +162,14 @@ jobs:
         shell: bash -e -x -l {0}
         run: |
           cd tests/pot3d
-          FC="gfortran -O3 -march=native -cpp" ./build_and_run_gfortran.sh
+          FC="gfortran -O3 -march=native -cpp -DOPEN_MPI=yes" ./build_and_run_gfortran.sh
 
       # build and validation without GFortran's optimization
       - name: POT3D Build and validation with GFortran without optimization using Open MPI (MPI only)
         shell: bash -e -x -l {0}
         run: |
           cd tests/pot3d
-          FC="gfortran -cpp" ./build_and_run_gfortran.sh
+          FC="gfortran -cpp -DOPEN_MPI=yes" ./build_and_run_gfortran.sh
 
   Compile_POT3D_with_LFortran_with_OpenMPI:
     name: "Build POT3D and validate with LFortran with Open MPI"
@@ -191,14 +191,14 @@ jobs:
         shell: bash -e -x -l {0}
         run: |
           cd tests/pot3d
-          FC="lfortran --fast --cpp" ./build_and_run_lfortran.sh
+          FC="lfortran --fast --cpp -DOPEN_MPI=yes" ./build_and_run_lfortran.sh
 
       # build and validation without LFortran's optimization
       - name: POT3D Build and validation with LFortran without optimization using Open MPI (MPI only)
         shell: bash -e -x -l {0}
         run: |
           cd tests/pot3d
-          FC="lfortran --cpp" ./build_and_run_lfortran.sh
+          FC="lfortran --cpp -DOPEN_MPI=yes" ./build_and_run_lfortran.sh
 
   Compile_POT3D_with_GFortran_with_MPICH:
     name: "Build POT3D and validate with GFortran with MPICH"