[mpich-discuss] Erroneous MPI type tag warning

Jed Brown jedbrown at mcs.anl.gov
Wed Dec 25 21:36:44 CST 2013

Junchao Zhang <jczhang at mcs.anl.gov> 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) =

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.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 835 bytes
Desc: not available
URL: <http://lists.mpich.org/pipermail/discuss/attachments/20131225/41b72295/attachment.sig>

More information about the discuss mailing list