On Aug 7 2019, Jeff Squyres (jsquyres) via mpi-forum wrote:
After much debate, the BigCount WG has decided that C11 _Generic just isn't worth it. That's no reason to penalize Fortran, though.
That is certainly the simplest solution. There may be others, but see below. At a wild guess, this is probably trappable by implementations (at some effort, and needing deep knowledge of the standards and issues) for MPI being called directly from conforming C compilers, but not from C++ ones using their C interface. And that is a very serious gotcha. On Aug 7 2019, Anthony Skjellum via mpi-forum wrote:
Conclusion: You can't use non-compliant MPI-4 with C11 compilers that are non-compliant with C11, except maybe with a special flag??? Is there more that I am missing?
It's a LOT more complicated than that, as I tried to explain earlier. Even when I was most active in this area, it would have taken me many hours, probably days, of investigation (including on systems to which I had no access), studying at least the C99, C11, C++ and MPI standards in great detail, and working out flow-charts, to be fairly sure of the situation. This area is a gibbering nightmare, and is a major reason the UK voted "no" to C99. On Aug 7 2019, Jeff Hammond via mpi-forum wrote:
"silently truncated at run time" is trivially addressed with -Wconversion or -Wshorten-64-to-32. The example program below is addressed by this.
Unfortunately, no. While I have no trouble using such options on MY code, I have frequently found them unusable on imported packages, because of the flood of non-errors they generate. For example, the following code is both common and reasonable, and includes narrowing conversions: int i; i = sizeof(double); float x; x = 1.0; On Aug 8 2019, Gropp, William D via mpi-forum wrote:
That -Wall is a lie is also true for gcc. Yes, this is a extremely poor design. If you want to provide -Wmostcommon then do that (and maybe abbreviate to -Wmost).
Agreed, but it's a digression here! I believe that the gcc people agree, too, but changing it now is just too evil. Regards, Nick Maclaren. _______________________________________________ mpi-forum mailing list firstname.lastname@example.org https://lists.mpi-forum.org/mailman/listinfo/mpi-forum