Attempt to make std::pair piecewise constructor noexcept

[Ville Voutilainen]

On Fri, 14 Dec 2018 at 00:14, François Dumont <frs.dumont@gmail.com> wrote:
>
> Hi
>
>      I had a try to make std::pair piecewise constructor noexcept
> qualified as you'll see in the attached diff. It will help to have more
> move semantic in associative containers.
>
>      But it doesn't work, is_nothrow_constructible<pair<int, int>,
> piecewise_construct_t, tuple<int>, tuple<int>>::value still false.
>
>      Could you let me know before I lose too much time if it is feasible
> or not ? Or at least if I am on the right path.
>
> Thanks for any help,

std::pair isn't constructible from typename
_Build_index_tuple<sizeof...(_Args1)>::__type, so it's not
nothrow_constructible from it either. is_constructible (and
is_nothrow_constructible) requires public access, and can't detect
what
your private constructors do.