Make F90 MPI_IN_PLACE, MPI_ARGVS_NULL, and MPI_STATUSES_IGNORE be uniqe types #8
Description
Per an e-mail exchange with Michael Kluskens, there appears to be benefit from making several of the MPI constants in F90 be unique types so that we can have unique interfaces that match just that senteniel. Specifically:
- We can disallow using those constants where they are not allowed
- We can prevent accidental bad arguments to functions (E.g., MPI_ARGVS_NULL is currently a double precision -- so someone could accidentally pass a double precision into MPI_COMM_SPAWN_MULTIPLE. Unlikely, but still possible -- a unique type for MPI_ARGVS_NULL would prevent this possibility)
See http://www.open-mpi.org/community/lists/users/2006/11/2115.php.