On Fri, Oct 15, 2021 at 3:27 PM Jonathan Wakely via SG10 < [email protected]> wrote:
> I think the following papers should have had a feature test macro: > > P0848 > <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0848r3.html> > Conditionally Trivial Special Member Functions > > P1330 > <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1330r0.pdf> > Changing the active member of a union inside constexpr > > I need a union in order to implement the std::variant changes in P2231 > <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2231r1.html> > and a conditionally trivial destructor makes it easier. In order to define > the __cpp_lib_constexpr_variant macro correctly I need to know if the union > usage is actually going to work, but there's no macro for P1330, so I can't > tell. > > A macro for constexpr destructors (P0784R7 > <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p0784r7.html>?) > might have been nice too, because if the compiler doesn't support it then > you get an error for even trying to declare a destructor constexpr. Without > a feature test macro there's no reliable way to try to use the feature. > This proposal added __cpp_constexpr_dynamic_alloc. > If all the compilers I need to support already implemented those features, > I wouldn't care, but they don't. > > https://godbolt.org/z/qG6d7TxhE > > > -- > SG10 mailing list > [email protected] > https://lists.isocpp.org/mailman/listinfo.cgi/sg10 >
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