As of v15.7, the PGI Fortran compiler does not properly support how
Open MPI uses the "USE ... ONLY" Fortran syntax to include modules
with conflicting symbol definitions (interestingly, pgfortran only has
a problem with this when compiling with -g).
In short, OMPI uses "USE :: module_aaa, ONLY: foo" and "USE ::
module_bbb, ONLY: bar" to use modules aaa and bbb, even though they
contain conflicting definitions for some symbols. However, the use of
the ONLY clause should preclude the inclusion of the conflicting
symbols -- as the word implies, it should direct the compiler to
*only* use the symbols identified by the clause (i.e., foo and bar, in
this example).
This commit adds a configure test for this capability. If the
compiler fails to build a simple test that mimics this behavior, then
disable the mpi_f08 bindings.
Fixesopen-mpi/ompi#857
