Junchao Zhang <[email protected]> writes:

To strictly obey MPI standard, we should declare MPI_2INT's type attribute as

typedef int mpich_array_mpi_2int[2]; static const MPI_Datatype mpich_mpi_2int MPICH_ATTR_TYPE_TAG_LAYOUT_COMPATIBLE (mpich_array_mpi_2int) = MPI_2INT;

Why would you want this? How is this a more "strict" interpretation of the standard? Note that for heterogeneous pairs, such as MPI_DOUBLE_INT, the struct definition is the only one that really makes sense and gets padding correct.

The warning happens again. In reality, struct {int value; int loc; } should have the same layout as int[2].

Guaranteed to be the same, yes.