26 Algorithms library [algorithms]

26.11 Specialized <memory> algorithms [specialized.algorithms]

26.11.8 construct_at [specialized.construct]

template<class T, class... Args>
  constexpr T* construct_at(T* location, Args&&... args);

namespace ranges {
  template<class T, class... Args>
    constexpr T* construct_at(T* location, Args&&... args);
}

Constraints: is_unbounded_array_v<T> is false.

The expression ::new (declval<void*>()) T(
declval<Args>()...) is well-formed when treated as an unevaluated operand ([expr.context]).

Mandates: If is_array_v<T> is true, sizeof...(Args) is zero.

Effects: Equivalent to: if constexpr (is_array_v<T>) return ::new (voidify(*location)) T[1](); else return ::new (voidify(*location)) T(std::forward<Args>(args)...);