[MPI3 Fortran] J3 / etc.

Rolf Rabenseifner rabenseifner at hlrs.de
Tue Oct 12 17:51:28 CDT 2010

Craig and Nick,

has the C-binding of Fortran CHARACTER*(*) dummy arguments
has also a chance to become part of Fortran 2013 by being
included in a type 2 TR that passes already summer 2011?

I ask because this is another major open gap to have a full BIND(C)
interface for all MPI routines. 

(The last gap will be to look at our callback functions.)

Best regards

----- Original Message -----
> From: "Craig Rasmussen" <crasmussen at newmexicoconsortium.org>
> To: "MPI-3 Fortran working group" <mpi3-fortran at lists.mpi-forum.org>
> Sent: Tuesday, October 12, 2010 11:41:55 PM
> Subject: Re: [MPI3 Fortran] J3 / etc.
> Jeff Squyres asked some important questions that I wanted to address
> to the entire group. This will also let others respond if they have a
> different take on it.
> On Tue, Oct 12, 2010 at 5:49 AM, Jeff Squyres <jsquyres at cisco.com>
> wrote:
> > 1. What exactly is in the 2008 spec and what exactly is in the TR?
> Fortran 2008 is essentially finished and will be released for final
> publication in a few months. It has nothing regarding further
> interoperability with C needed by Fortran MPI-3. The TR (J3 document
> 10-165r2) has the assumed type and assumed rank (TYPE(*) and
> DIMENSION(..)) specifications needed by MPI-3. This part of the TR is
> "finished". Currently we are working around the edges of this,
> nailing down the specification of some functions that modify members
> of the array descriptor that will be passed to C. None of this stuff
> (that we are currently working on) rises to the level of the MPI
> standard (it would only affect an MPI vendors implementation).
> > 2. How binding is the TR?
> This is a type 2 TR which means that, if passed, it will officially
> become part of the Fortran 2013 standard. It is actually a good thing
> to be a TR in this case because vendors can work on it sooner,
> presumably even before they finish F2008, if users demand it.
> > 3. What is the process for the TR to become part of the 2008 (or
> > later) spec?
> As mentioned above it is a formality. There is another type of TR
> that can forever live outside of the standard, but not a type 2 TR.
> >
> > One case that has been cited as a cause for concern is co-array
> > fortran -- apparently that started life as a TR and as later brought
> > into the formal standard itself, BUT it changed *significantly*
> > between its life as a TR and its life in the standard.
> What was originally known as Co-Array Fortran (CAF), was designed by
> Bob Numric and John Reid and implemented by Cray. CAF as such was
> never standardized (separate from Fortran), but became part of Fortran
> 2008 standard; it is no longer CAF but just part of Fortran. There
> are differences between CAF and Fortran 2008 but I don't know if I
> would call them significant. Some stuff (collectives) were left for
> later and will be done in a TR that will be come part of F2013.
> Once the further interoperability with C TR passes, (probably in June
> at the WG5 world body meeting in Germany) I can see no reason why the
> MPI Forum cannot safely rely on the standard. What really counts in
> the end is whether Fortran vendors will implement the standard. The
> record has shown that the vendors will implement what the users ask
> for. The original interoperability standard in F2003 was the first
> part of F2003 that vendors implemented, in part because of a poll I
> took of the HPC community, that said users overwhelmingly thought
> interoperability with C was the most important part of the 2003
> standard.
> -craig
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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: Allmandring 30)

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