[Mpi-22] Ticket #46: Addconst Keyword to the C bindings- implementation

[Pavan Balaji]

> 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