On May 2, 2013, at 11:27 AM CDT, Lisandro Dalcin <[email protected]> wrote:

On 2 May 2013 18:58, Dave Goodell <[email protected]> wrote:

...

Thanks for letting us know. I've created a ticket to track this and commented on your suggestions there:

https://trac.mpich.org/projects/mpich/ticket/1833#comment:1

Thanks. BTW, you are right. This was indeed bad API usage from the user. All neighbor collectives should check that the communicator is an INTRAcommunicator with cart|graph|distgraph topology attached and otherwise generate a proper error (of class MPI_ERR_COMM?)

Sounds right to me. There might be a more appropriate MPI_ERR_* class, but I'd have to re-read the list to be sure. -Dave