[PATCH] Disable -Wctor-dtor-privacy warnings for some standard types

[Daniel Krügler]

Am Fr., 14. Juni 2019 um 16:05 Uhr schrieb Jonathan Wakely <jwakely@redhat.com>:
>
> These types are not constructible by design, so we never want warnings
> for them, even with -Wsystem-headers.
>
>         * include/experimental/type_traits (experimental::nonesuch): Use
>         pragma to disable -Wctor-dtor-privacy warnings.
>         * include/std/type_traits (__is_convertible_helper<From, To, false>)
>         (__is_nt_convertible_helper<From, To, false>, __nonesuch): Likewise.
>
> Tested x86_64-linux, committed to trunk.

Unless I'm misunderstanding something, __nonesuchbase (twice) would
not be affected by that warning, so maybe the start of the
corresponding warning suppression could be moved after their
definition? Or did you do it that way to keep __nonesuchbase and
nonesuch close together?

- Daniel