[mpiwg-tools] Fwd: [mpi-forum/mpi-issues] MPI RMA integer interfaces for AINT arguments (Issue #528)

[Joachim Protze]

Hi tools folks,

We should have an eye on this issue. Has this the potential to break 
PMPI Wrappers?

Best
Joachim

-------- Weitergeleitete Nachricht --------


   Problem

RMA absolutely did the right thing with |MPI_Aint| size and displacement 
arguments.

In C, it is no problem to pass 32b integers to these arguments when AINT 
is 64b, because C type promotion rules just work.

In Fortran, I cannot do this, because an integer literal is not 
compatible with an AINT argument. I find it tedious to have to declare a 
variable just for this, or to explicitly cast with 
|integer(100,MPI_ADDRESS_KIND)|.


   Fortran

! USE mpi_f08
! MPI_Win_allocate(size, disp_unit, info, comm, baseptr, win, ierror)
!    USE,INTRINSIC  ::  ISO_C_BINDING, ONLY : C_PTR
!INTEGER(KIND=MPI_ADDRESS_KIND),INTENT(IN)::  size
!INTEGER,INTENT(IN)::  disp_unit
!    TYPE(MPI_Info),INTENT(IN)::  info
!    TYPE(MPI_Comm),INTENT(IN)::  comm
!    TYPE(C_PTR),INTENT(OUT)::  baseptr
!    TYPE(MPI_Win),INTENT(OUT)::  win
!INTEGER, OPTIONAL,INTENT(OUT)::  ierror
program  main
    use iso_fortran_env
    use mpi_f08
    implicit none
    integer(kind=MPI_ADDRESS_KIND)::  as=  100
    type(c_ptr)::  XA
    type(MPI_Win)::  WA
    TYPE(MPI_Comm)::  comm=  MPI_COMM_WORLD
    call  MPI_Win_allocate(as,1, MPI_INFO_NULL, comm, XA, WA)
    call  MPI_Win_allocate(100,1, MPI_INFO_NULL, comm, XA, WA)
end program  main

% mpifort y.F90
y.F90:20:60:
     20|    call MPI_Win_allocate(100, 1, MPI_INFO_NULL, comm, XA, WA)
        |                                                             1
Error: There is no specific subroutinefor  the generic'mpi_win_allocate' 
  at (1)


   C

#include  <mpi.h>
int  main(void)
{
    MPI_Aint as =100;
    int  * XA;
    MPI_Win WA;
    MPI_Win_allocate(as,1, MPI_INFO_NULL, MPI_COMM_WORLD, XA, &WA);
    MPI_Win_allocate(100,1, MPI_INFO_NULL, MPI_COMM_WORLD, XA, &WA);
}

% mpicc y.c&&  echo  SUCCESS
SUCCESS


   Proposal

Use Fortran does polymorphism and add subroutine declarations for 
default integer arguments.

This proposal applies not to just MPI_Win_allocate but any RMA function 
that uses AINT scalar arguments.


   Changes to the Text


   Impact on Implementations


   Impact on Users


   References and Pull Requests

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