On Mar 25, 2013, at 2:35 PM, Bill Long <longb@cray.com> wrote:

I'm strongly in favor of option 3. It is the only option that allows
the possibility of underscore name mangling disappearing in the future.
I think most (if not all) MPI Fortran implementations will eventually
evolve to thin wrappers calling the C API.

Remember that Open MPI can never do this approach since our C handles != Fortran handles, and Fortran wrappers will not be able to reach back into the back-end C MPI objects (at least, not without a truckload of extra interop code -- the Fortran bindings layer would have to gain an understanding of the back-end MPI C objects, and that seems like a terrible idea).

This may be beyond the scope of an errata but I don't want to close off this possibility. Otherwise the MPI standard will still REQUIRE implementations to go OUTSIDE of the Fortran standard. This to me is a big deal and was one of the two big reasons in my opinion why we did MPI-3 for Fortran in the first place (the other was type safety). I really hate to go to all the work we did and then give up on an MPI standard that is out of compliance with language standards.