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

[Jeff Squyres (jsquyres)]

On Jun 9, 2014, at 8:31 PM, Jeff Squyres (jsquyres) <jsquyres at cisco.com> wrote:

> Yeah, I kinda came to that same conclusion over the weekend (that OMPI's MPI_SIZEOF support in mpif.h would have to depend on which Fortran compiler is used).  Urrrgh...


Actually, this doesn't work, either.  If you have an mpif.h that contains an "INTERFACE MPI_Sizeof", the compiler will treat it differently depending on whether it is included from source.f or source.f90 (and probably other variants, too).  Gaahhh!

This means that it is not possible -- and has never been possible -- to have an MPI-3.0 compliant MPI_SIZEOF interface in mpif.h.  An errata is therefore required.

I open to suggestions.

1. One obvious possibility is to re-instate "extended Fortran support"-like language, a la MPI-2.2.  This does not make it possible to have MPI_SIZEOF in mpif.h, however, so I don't think it really solves the problem.

2. Another possibility is to say that MPI_SIZEOF is only available in the mpi and mpi_f08 modules (e.g., add an exception in MPI-3.x 17.1.4 saying that MPI_SIZEOF support is excluded from mpif.h).  Per Bill Gropp's email (http://lists.mpi-forum.org/mpiwg-fortran/2014/06/1572.php), we'll actually have to add exceptions / remove references to overloading for all mpif.h cases -- not just MPI_SIZEOF.

Thoughts?

-- 
Jeff Squyres
jsquyres at cisco.com
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