inline void swap(slice &other) noexcept; #if defined(DOXYGEN) ||

Question

inline void swap(slice &other) noexcept; #if defined(DOXYGEN) ||

\
(defined(__cpp_lib_string_view) && __cpp_lib_string_view >= 201606L)
template <class C, class T>
void swap(::std::basic_string_view<C, T> &view) noexcept {
static_assert(sizeof(C) == 1, "Must be single byte characters");
const auto temp = ::std::basic_string_view<C, T>(*this);
*this = view;
view = temp;
}
#endif /* __cpp_lib_string_view >= 201606L */
зачем если есть std::basic_string_view<CharT,Traits>::swap ?