[MPI3 Fortran] Fwd: Re: Fwd: [Mpi-comments] MPI 3.0:Fortran 2008 interface - issue with the LOGICAL kind

Bill Long longb at cray.com
Mon Mar 4 10:29:24 CST 2013

As an example, this is from page 606 in the spec:

   USE mpi

If you expect to support external linkage names like "MPI_Send_f", then 
the BIND(C) is required.

There is no problem with the normal MPI routines since they go through 
wrappers and the wrapper can convert the LOGICAL value into an int for 
sending on to C (and back, if necessary).

The callbacks are more difficult.  But there is no need to mess up the 
normal routines, with the associated undesirable side effects.


-------- Original Message --------
Subject: Re: [MPI3 Fortran] Fwd: [Mpi-comments]	MPI	3.0:Fortran	2008 
interface - issue with the	LOGICAL kind
Date: Mon, 4 Mar 2013 10:13:36 -0600
From: Bill Long <longb at cray.com>
Reply-To: <longb at cray.com>
Organization: Cray Inc.
To: <mpi3-fortran at lists.mpi-forum.org>

On 3/4/13 9:47 AM, Rolf Rabenseifner wrote:
> Dear all,
> I forget to say thank you to all of you who helped to solve
> this hard problem. It was a really helpful discussion.
> It is a pity that we could not keep the BIND(C) for
> all routines in mpi_f08, which was one goal with mpi_f08 and TS 29113.
> In my proposal #364, we have to remove BIND(C) from
>   - the 30 normal MPI routines with LOGICAL arguments,

I would be strongly against this, as it prevents putting the wrapper
routines in a module.  We will have to start over from scratch with a
vastly inferior implementation, with reduced performance.   (Unless you
concurrently delete completely the mpif.h include file, in which case
the BIND(C) on the wrappers is no needed any longer.)

>   - the  9 MPI routines with callbacks in the argument list,
>   - and 10 predefined callbacks,
> i.e., from 49 out of 357 MPI routines.
> I do not see a better solution that can be done by the MPI Forum.
> Better solutions are still possible for the 30 normal routines
> and/or for the 9 routines with callback-arguments as soon as
> the Fortran standard will include some additions and
> those additions are provided by the compilers - but if this
> will happen then it will not happen soon.
> It was luck that all routines with buffer arguments do not
> have also a LOGICAL argument.
> Best regards
> Rolf
> ------------------
> Malcolm and all MPI implementors,
> and TOOLS implementors,
> First Malcolm, thank you for your helpful answer.
> After all the discussion, the MPI-3.0 errata decision is
> very simple: Remove BIND(C) everywhere where LOGICAL is around.
> I did it in the ticket #364
> https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/364
> I hope that one of the implementors with Fortran knowledge goes
> through my proposal and returns an "okay" as a review on the ticket.
> The major changes:
>   - BIND(C) removed on all callback abstract interfaces.
>   - BIND(C) removed on all predefined callbacks.
>   - Creating a new routine group "MPI_TEST" for all MPI routines
>     with LOGICAL arguments, except MPI_OP_CREATE, which is already
>     in an own group.
>   - Telling that the routines in the groups MPI_TEST,
>     cannot be implemented with BIND(C) in Fortran 2008 + TS 29113 and earlier.
> TOOLS implementors should be aware that I added this new routine group.
> Best regards
> Rolf
> ----- Original Message -----
>> From: "Malcolm Cohen" <malcolm at nag-j.co.jp>
>> To: "MPI-3 Fortran working group" <mpi3-fortran at lists.mpi-forum.org>
>> Sent: Monday, March 4, 2013 3:56:50 AM
>> Subject: Re: [MPI3 Fortran] Fwd: [Mpi-comments] MPI 3.0:Fortran 2008 interface - issue with the LOGICAL kind
>>>     (B1) Is it possible, that a BIND(C) routine
>>>          has a dummy argument that is a non-BIND(C)
>>>          ABSTRACT INTERFACE procedure argument?
>> That is not possible: all dummy arguments of a BIND(C) routine must be
>> interoperable - for procedures that requires BIND(C).
>> It would be reasonable to extend C_FUNLOC and C_F_PROCPOINTER to
>> permit
>> non-interoperable procedures, similarly to how we permit
>> non-interoperable
>> variables in C_LOC and C_F_POINTER. Then the argument could be
>> C_FUNPTR (by
>> value). I don't know whether this would help you though.
>>>     (B2) Do we have any problem with
>>>          the TYPE(C_PTR), VALUE dummy arguments
>>>          in the ABSTRACT INTERFACE MPI_User_function
>>>          on MPI-3.0 page 183 line 45 - page 184 line 3
>>>          if the we remove the BIND(C) from this
>>>          ABSTRACT INTERFACE (i.e. on page 183, line 47).
>> No problem.
>> Cheers,
>> --
>> ................................Malcolm Cohen, Nihon NAG, Tokyo.
>> _______________________________________________
>> mpi3-fortran mailing list
>> mpi3-fortran at lists.mpi-forum.org
>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-fortran

Bill Long                                           longb at cray.com
Fortran Technical Support    &                 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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