[PATCH RFC] c++: mangle function template constraints

[Jonathan Wakely]

On Mon, 20 Nov 2023 at 02:56, Jason Merrill wrote:
>
> Tested x86_64-pc-linux-gnu.  Are the library bits OK?  Any comments before I
> push this?

The library parts are OK.

The variable template is_trivially_copyable_v just uses
__is_trivially_copyable so should be just as efficient, and the change
to <bit> is fine.

The variable template is_trivially_destructible_v instantiates the
is_trivially_destructible type trait, which instantiates
__is_destructible_safe and __is_destructible_impl, which is probably
why we used the built-in directly in <variant>. But that's an
acceptable overhead to avoid using the built-in in a mangled context,
and it would be good to optimize the variable template anyway, as a
separate change.