[MPIWG Fortran] Another MPI_SIZEOF question

[William Gropp]

Yes, despite the new claims in MPI-3, the mpif.h file for MPICH has been required to be backward compatible with Fortran 77, since there are still Fortran 77 codes.  MPI-3 essentially mandated that Fortran 77 compilers be unable to compile standard conforming MPI codes, and the MPI implementations that choose to permit existing codes to be compiled decided to violate the standard in this place.

Note that storage_size appeared in Fortran 2008, not earlier versions of Fortran 9x, which is why we added MPI_SIZEOF.

Having said that, yes, I think that deprecating but not yet removing MPI_SIZEOF makes sense.

Bill

William Gropp
Director, Parallel Computing Institute
Thomas M. Siebel Chair in Computer Science
University of Illinois Urbana-Champaign





On Jun 6, 2014, at 9:11 AM, Jeff Squyres (jsquyres) wrote:

> It strikes me that the current MPI_SIZEOF text does not limit this function to the mpi or mpi_f08 modules, meaning that it needs to be supported/available in mpif.h as well.
> 
> Since SIZEOF can only be implemented via overloaded procedures, this means that implementations have to put an INTERFACE block with the overloaded procedures for MPI_SIZEOF in mpif.h.  Yowza!  This goes against a long-standing tradition of not including procedure prototypes in mpif.h.
> 
> If I'm interpreting this properly, it looks like neither Open MPI nor MPICH do this correctly.
> 
> Am I correct in this deduction?
> 
> Random side note: this makes me wonder how much MPI_SIZEOF is really used...
> 
> -- 
> Jeff Squyres
> jsquyres at cisco.com
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