template <class P> iterator insert(P&& x);
template <class P> iterator insert(const_iterator position, P&& x);
Effects:
The first form is equivalent to
return emplace(std::forward<P>(x)). The second form is
equivalent to
return emplace_hint(position, std::forward<P>(x)).Remarks:
These signatures shall not participate in overload resolution
unless
is_constructible_v<value_type, P&&> is
true.