[MPI3 Fortran] Fortran proposal w.r.t. BIND(C)/logical/linker symbols/etc. (take 2)

[Jeff Squyres (jsquyres)]

With lots of feedback and discussions since Craig's+my proposal on April 22, we have updated our proposal to be the following (remember: if everyone likes these ideas, then we can go see what this means in terms of the text of chapter 17):

1. Remove BIND(C) from all prototypes in the spec.

2. As has been the case since MPI-1, all Fortran symbols must be interceptable at link time:

Class 1: For all MPI routines "MPI_<foo>" with a void * choice argument, or with no choice argument:

A) If mpif.h/mpi module is provided, an external must be provided with the name "MPI_<foo>" that uses the Fortran calling conventions and has INTEGER handle arguments, as specified in Annex A.

B) If the mpi_f08 module is provided, an external must be provided with the name "MPI_<foo>_<f08_buffer>" that uses the Fortran calling conventions and has derived type handle arguments, as specified in Annex A.

Class 2: For all MPI routines "MPI_<foo>" with a descriptor choice argument:

A) If mpif.h/mpi module is provided, an external must be provided with the name "MPI_<foo>_<old_descriptor>" that uses the Fortran calling conventions and has INTEGER handle arguments, as specified in Annex A.

B) If the mpi_f08 module is provided, an external must be provided with the name "MPI_<foo>_<f08_descriptor>" that uses the Fortran calling conventions and has derived type handle arguments, as specified in Annex A.

*** The exact suffixes <f08_buffer>, <old_descriptor>, and <f08_descriptor> are up for discussion.

3. Implementations that want to use CONTAIN blocks for inlined implementations -- probably for performance reasons -- can supply 2 Fortran libraries: one with CONTAIN/inlined implementations, and a second one with interceptable symbols (perhaps this should be an Advice to Implementors?).

-- 
Jeff Squyres
jsquyres at cisco.com
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