from the ROMIO sources :
/* Any MPI implementation that wishes to follow the thread-safety and
error reporting features provided by MPICH must implement these
four functions. Defining these as empty should not change the behavior
of correct programs */
the MPIO_DATATYPE_ISCOMMITTED macro now always set err_=0
this is an optimistic approach for Open MPI, but it is likely other upper
layers already checked the datatype was committed.
not setting err_ is incorrect since it can lead to some use of uninitialized
variable.
Fixesopen-mpi/ompi#404
74a46863ca