CHECK_TYPE(3, datatype)
int size = datatype->get_extent() * count;
+ xbt_assert(size > 0);
void* recvbuf = xbt_new0(char, size);
retval = MPI_Sendrecv(buf, count, datatype, dst, sendtag, recvbuf, count, datatype, src, recvtag, comm, status);
if(retval==MPI_SUCCESS){