[SG10] A feature macro for mandatory copy elision

Nelson, Clark clark.nelson at intel.com
Mon Oct 9 18:10:54 CEST 2017


Perhaps I should also ask: should the name of the macro use the word "mandatory", or would "guaranteed" (as from the original document title) be better?

Clark

> -----Original Message-----
> From: features-bounces at open-std.org [mailto:features-bounces at open-
> std.org] On Behalf Of Nelson, Clark
> Sent: Monday, October 09, 2017 09:09
> To: Richard Smith <richard at metafoo.co.uk>; Ville Voutilainen
> <ville.voutilainen at gmail.com>
> Cc: features at isocpp.open-std.org <Features at open-std.org>
> Subject: Re: [SG10] A feature macro for mandatory copy elision
> 
> > After a while pondering, the best example I've got to demonstrate a
> > need for the feature test macro is something like this:
> >
> > #ifdef __cpp_mandatory_copy_elision
> >
> > NoCopyNoMove indirectFactory() {
> >   return factory(1); // ill-formed prior to C++17
> > }
> > #endif
> 
> At this point I gather that no one has an objection to providing a
> macro for mandatory copy elision.
> 
> Should SD-6 contain an example like this one? It seems to me that
> there ought to be a different definition of indirectFactory under an
> #else, but I don't know what it should look like.
> 
> Clark
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