constexpr year_month_weekday(const chrono::year& y, const chrono::month& m,
const chrono::weekday_indexed& wdi) noexcept;
constexpr year_month_weekday(const sys_days& dp) noexcept;
constexpr explicit year_month_weekday(const local_days& dp) noexcept;
constexpr year_month_weekday& operator+=(const months& m) noexcept;
constexpr year_month_weekday& operator-=(const months& m) noexcept;
constexpr year_month_weekday& operator+=(const years& y) noexcept;
constexpr year_month_weekday& operator-=(const years& y) noexcept;
constexpr chrono::year year() const noexcept;
constexpr chrono::month month() const noexcept;
constexpr chrono::weekday weekday() const noexcept;
constexpr unsigned index() const noexcept;
constexpr chrono::weekday_indexed weekday_indexed() const noexcept;
constexpr operator sys_days() const noexcept;
constexpr explicit operator local_days() const noexcept;
constexpr bool ok() const noexcept;