// In header: <detail/inplace.hpp>

template<typename T = void> 
struct inplace_allocator {
  // types
  typedef T value_type;

  // public member functions
  T * allocate(std::size_t) const;
  constexpr void deallocate(T *, size_t) const noexcept;
  constexpr bool operator==(const inplace_allocator &) const noexcept;
  constexpr bool operator!=(const inplace_allocator &) const noexcept;
};