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From: Brian Barrett (bbarrett_at_[hidden])
Date: 2007-06-19 10:41:41

On Jun 19, 2007, at 8:35 AM, Terry D. Dontje wrote:

> Rainer Keller wrote:
>> Hello dear all,
>> with the current numbering in mpif-common.h, the optional ddt
>> MPI_REAL2 will
>> break the binary compatibility of the fortran interface from v1.2 to
>> v1.3
>> (see r15133).
>> Now apart from MPI_REAL2 being of let's say rather minor importance,
>> the group
>> may feal that the numbering of datatypes is crucial to the end user
>> and the
>> (once agreed upon) allowed binary incompatibility for major version
>> number
>> changes is void.
>> (The most important datatype that this change affects is
>> users will need to recompile their code with v1.3...)
>> Please raise Your hand if anybody cares.
> <raising hand>
> Sun cares very much about this for the exact reason you state (Binary
> compatibility).
> I'd prefer this ddt is placed at the end of the list.

I think we should try to avoid binary compatibility changes at the
MPI layer if we can, even between our "major" releases. Especially
if they don't take lots of work. Now if only we would stop changing
the size of ompi_communicator_t :).