It is important to have the mpi_f08 Type(MPI_Status) be the same
length (in bytes) as the mpif.h status (which is an array of
MPI_STATUS_SIZE INTEGERs). The reason is because MPI_Status_ctof()
basically does the following:
MPI_Fint *f_status = ...;
int *s = (int*) &c_status;
for i=0..sizeof(MPI_Status)/sizeof(int)
f_status[i] = c_status[i];
Meaning: the Fortran status needs to be able to hold as many INTEGERs
are there are C int's that can fit in sizeof(MPI_Status) bytes.
This is because a Fortran INTEGER may be larger than a C int (e.g.,
Fortran 8 bytes vs. C 4 bytes). Hence, the assignment on the Fortran
side will take sizeof(INTEGER) bytes for each sizeof(int) bytes in the
C MPI_Status.
This commit pads out the mpi_f08 Type(MPI_Status) with enough INTEGERs
to make it the same size as an array of MPI_TYPE_SIZE INTEGERs.
Hence, MPI_Status_ctof() will work properly, regardless of whether it
is assinging to an mpi_f08 Type(MPI_Status) or an mpif.h array of
MPI_STATUS_SIZE INTEGERs.
Thanks to @ahaichen for reporting the issue.
Signed-off-by: Jeff Squyres <jsquyres@cisco.com>
98bc7af7d4