[MPI3 Fortran] (j3.2006) (SC22WG5.3886) [ukfortran] [MPI3 Fortran] MPI non-blocking transfers

[Van Snyder]

On Thu, 2009-01-22 at 08:11 -0800, Bill Long wrote:
> 
> >> One simple step toward solving the problem is to write an extra
> >> interface layer that includes the argument, which then calls the real
> >> MPI wait routine, not passing that argument.  Then declaring the buffer
> >> and the dummy argument of the wait routine interface layer to be
> >> ASYNCHRONOUS ought to work, according to the rules we already have in
> >> place for Fortran asynchronous I/O.
> >>
> 
> The basic problem with adding a buffer argument to a variant of the
> MPI_wait routines is that the buffer variable may not be accessible in
> the scoping unit of the call.  This seems like a fatal flaw with this
> approach.

If it's not accessible in the scoping unit of the call, then the
compiler can't possibly fiddle with it, and in particular can't possibly
move references to it across the call.