[MPIWG Fortran] BIND(C) attribute of MPI callback functions

[Rolf Rabenseifner]

Bill,

The reason for removal of BIND(C) was simple:
Four callbacks contain LOGICAL arguments
and we learnt that LOGICAL and BIND(C) does not work together.
Therefore the errata is correct.

I hope you find a solution for storing the callback pointer
in a C structure and to bring it back to Fortran.
I expect that calling the Fortran callbacks
in a portable way may require Fortran code
that calls the callback.

Best regards
Rolf


----- Original Message -----
> From: "Bill Long" <longb at cray.com>
> To: "MPI-WG Fortran working group" <mpiwg-fortran at lists.mpi-forum.org>
> Sent: Tuesday, July 1, 2014 9:06:05 PM
> Subject: Re: [MPIWG Fortran] BIND(C) attribute of MPI callback functions
> 
> 
> On Jul 1, 2014, at 2:00 PM, Junchao Zhang <jczhang at mcs.anl.gov>
> wrote:
> 
> > Hello,
> >   Errata for MPI-3.0 removed the BIND(C) attribute of MPI callback
> >   functions. But in an implementation, to pass the Fortran
> >   procedure to the backend C, I need to get its C function pointer
> >   with c_funloc, as the following code shows. When I compile it
> >   with IBM XLF 15.1, it complains with such an error "1516-203 (S)
> >   The argument to the intrinsic procedure C_FUNLOC must be a
> >   procedure with the BIND(C) attribute." In my experiments, gcc
> >   and Cray ftn are fine with it.  Looking at
> >   https://gcc.gnu.org/onlinedocs/gfortran/C_005fFUNLOC.html, I
> >   find c_funloc indeed requires an interoperable function
> >   argument. Any comments?
> 
> This requirement on the argument of C_FUNLOC was removed by TS 29113,
> subclause 8.1 “Removed restrictions on ISO_C_BINDING module
> procedures”.
> 
> Cheers,
> Bill
> 
> 
> 
> > 
> > subroutine MPI_Comm_create_errhandler_f08(comm_errhandler_fn,
> > errhandler, ierror)
> >     use, intrinsic :: iso_c_binding, only : c_funloc, c_int,
> >     c_funptr
> >     use :: mpi_f08, only : MPI_Errhandler,
> >     MPI_Comm_errhandler_function
> >     use :: mpi_c_interface, only : c_Errhandler,
> >     MPIR_Comm_create_errhandler_c
> > 
> >     implicit none
> > 
> >     procedure(MPI_Comm_errhandler_function) :: comm_errhandler_fn
> >     type(MPI_Errhandler), intent(out) :: errhandler
> >     integer, optional, intent(out) :: ierror
> > 
> >     type(c_funptr) :: comm_errhandler_fn_c
> > 
> >     comm_errhandler_fn_c = c_funloc(comm_errhandler_fn) !! xlf
> >     issues an error
> >     ierror_c = MPIR_Comm_create_errhandler_c(comm_errhandler_fn_c,
> >     errhandler%MPI_VAL)
> >     ...
> > end subroutine MPI_Comm_create_errhandler_f08
> > 
> > --Junchao Zhang
> > _______________________________________________
> > mpiwg-fortran mailing list
> > mpiwg-fortran at lists.mpi-forum.org
> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran
> 
> Bill Long
>                                                                       longb at cray.com
> Fortran Technical Suport  &                                  voice:
>  651-605-9024
> Bioinformatics Software Development                     fax:
>  651-605-9142
> Cray Inc./ Cray Plaza, Suite 210/ 380 Jackson St./ St. Paul, MN 55101
> 
> 
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> 

-- 
Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner at hlrs.de
High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530
University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832
Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner
Nobelstr. 19, D-70550 Stuttgart, Germany . . . . (Office: Room 1.307)