On Tue, Jun 26, 2012 at 8:19 AM, Jeff Squyres <[email protected]> wrote:

On Jun 26, 2012, at 12:14 PM, Jed Brown wrote:

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On Tue, Jun 26, 2012 at 6:13 AM, Jeff Squyres <[email protected]> wrote: There are a few C++-specific datatypes for which it would be worth introducing new C datatypes (e.g., MPI_CXX_COMPLEX). It's too bad that no one realized this until now, because this won't make the MPI-3 deadline. But it could be part of MPI-3.1 or errata, or some such.

Two people in offline discussions have suggested that C bindings to the std::complex types (I'm not aware of anything else that #281 will lose) might qualify as ticket 0.

I'd have to see the exact changes to get a better feel for it, but I would be a little surprised if these changes could be considered ticket 0, for two reasons:

1. "ticket 0" is reserved for typos or other insignificant changes that do not change the meaning of the standard. Indeed, the standard would still be fine without those ticket 0 changes -- the idea is that ticket 0 changes make the standard read better, etc.

2. Adding MPI datatypes for uin64_t (and friends) was a standalone ticket. I would think that this would be very similar.

Okay. FWIW, I think this request is only to preserve the table "C++-only Named Predefined Datatypes" as in the MPI-2.2 standard, but with namespaced MPI:: names replaced by the MPI_CXX_ prefix (and s/Complex/std::complex/ because that was apparently a typo). From the discussion, it sounds like removing support for these types was an accidental/unrecognized side-effect of bulk-removing the C++ bindings in #281.