[MPIWG Fortran] MPI_SIZEOF: Errata required (was: Another MPI_SIZEOF question)

[Rolf Rabenseifner]

Yes, the "Extended Support" listed of about 5 additional routines,
but as far as I understand, MPI_SIZEOF is the only one
that needs an INTERFACE description in mpif.h.

All other routines are without any implementation-problems.

Therefore, it would be enough to allow in the special case
that MODULE (and INTERFACE) are not supported by the target compiler, 
that 
 - the Fortran Support requires only mpif.h (same as in MPI-2.0), 
   and
 - MPI_SIZEOF is not provided.

Additionally, we can restrict the MPI_SIZEOF support only 23 dimensions 
 - in mpif.h
 - or generally if TS29113 or other non-Standard methods
   are not available,
supposed that "DOUBLE PRECISION" is the longest
Fortran type Name:

123456789012345678901234567890123456789012345678901234567890123456789012
      SUBROUTINE MPI_SIZEOF(x,n)
      DOUBLE PRECISION x(1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,*)
!                        1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
What did mpich and OpenMPI in the past with MPI_SIZEOF? 

Rolf

----- Original Message -----
> From: "William Gropp" <wgropp at illinois.edu>
> To: "MPI-WG Fortran working group" <mpiwg-fortran at lists.mpi-forum.org>
> Sent: Saturday, June 14, 2014 6:36:35 AM
> Subject: Re: [MPIWG Fortran] MPI_SIZEOF: Errata	required	(was:	Another	MPI_SIZEOF question)
> 
> 
> Not quite true.  See my email, which gives specific locations in the
> standard for the relevant text.  Note also that MPI_SIZEOF is *not*
> the only function that is not included in the "basic" Fortran
> support - the routines to create a type based on precision and range
> are also not required for basic support.  
> 
> 
> I think there are two options for the so-called Fortran 77 support.
>  Continue to support the "basic" support, as defined in MPI-2, or
> delete it entirely.  Anything else is likely to leave errors and
> mistakes.  And while I agree with Jeff that its not good practice to
> remove something like F77 support at a point release, I believe that
> the language in the standard removed Fortran 77 with 3.0.  We're
> just now recognizing that.
> 
> 
> Bill
> 
> 
> 
> 
> 
> 
> 
> William Gropp
> Director, Parallel Computing Institute Thomas M. Siebel Chair in
> Computer Science
> 
> 
> University of Illinois Urbana-Champaign
> 
> 
> 
> 
> 
> 
> 
> On Jun 13, 2014, at 10:32 AM, Rolf Rabenseifner wrote:
> 
> 
> 2) The requirement of having this function in mpif.h was changed:
> 
>   MPI-2.0 through 2.2 requiered MPI_SIZEOF in mpif.h
>   "unless the target compiler does not support modules
>   or KIND-parametrized types."
> 
>   This restriction was removed.
> 
> 
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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
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