To:       J3                                                  08-185r1
From:     Craig Rasmussen
Subject:  Request for new features from MPI Forum
Date: 2008 May 15

The MPI Forum has been restarted in order to update the Message Passing
Interface (MPI) standard.  As part of this standardization effort, a new
Fortran binding will be created for version 3.0 of the MPI standard.  The
MPI Forum has requested that J3 consider modifying the Fortran standard
to accomplish the following:

  1. A mechanism to suppress copy-in/copy-out semantics for MPI
     asynchronous operations.

  2. Suppress argument checking for MPI choice buffers (C void * formal
     parameters).

A series of straw votes were taken at J3 meeting 184 to determine how to
address the request from the MPI Forum.  The results were:

  1. The VOLATILE attribute should be given to both the actual and dummy
     arguments to suppress copy-in/copy-out.

  2. The J3 committee voted to consider three different candidates for
     suppressing argument checking of C void * formal parameters.  WG5
     will be asked to consider this as a work item for the C Interop TR.
     The candidates for the mapping of dummy arguments to void * parameters
     are:

       a. Create a new derived type, TYPE(C_VOID), in the ISO_C_BINDING
          intrinsic module.

       b. Add an IGNORE(TKR) attribute for dummy arguments.  This
          attribute can optionally ignore any combination of type, kind,
          and rank.

       c. Create new syntax, TYPE(*), to allow any type actual argument.
          When combined with DIMENSION(*), this is effectively equivalent
          syntax for IGNORE(TKR).

J3 wishes to make the views expressed in this paper known to the MPI
Forum.