The diff for the proposal was almost 10,000 lines long, which is a little frightening for 2.2 change.
FWIW, it took only a few days to implement. Though it's a long patch, most changes are trivial.
However, the places the constness is cast away for the send buffer raises some issues. In particular, for eager, contiguous sends, the send buffer constness is cast away in MPID_Send, which is the second
MPID_Send already uses a const, so we are not actually casting away the constness.
Open MPI's low layer communication interface is based on a iovec-like interface. Like most interfaces, the iovec-like interface is shared between the send and receive calls.
Yes, we faced similar issues in some places (mainly in ROMIO), but they were only a handful if I remember correctly. -- Pavan -- Pavan Balaji http://www.mcs.anl.gov/~balaji