constexpr explicit year(int y) noexcept;
constexpr year& operator++() noexcept;
constexpr year operator++(int) noexcept;
constexpr year& operator--() noexcept;
constexpr year operator--(int) noexcept;
constexpr year& operator+=(const years& y) noexcept;
constexpr year& operator-=(const years& y) noexcept;
constexpr year operator+() const noexcept;
constexpr year operator-() const noexcept;
constexpr bool is_leap() const noexcept;
constexpr explicit operator int() const noexcept;
constexpr bool ok() const noexcept;
static constexpr year min() noexcept;
static constexpr year max() noexcept;
constexpr bool operator==(const year& x, const year& y) noexcept;
constexpr strong_ordering operator<=>(const year& x, const year& y) noexcept;
constexpr year operator+(const year& x, const years& y) noexcept;
constexpr year operator+(const years& x, const year& y) noexcept;
constexpr year operator-(const year& x, const years& y) noexcept;
constexpr years operator-(const year& x, const year& y) noexcept;
template<class charT, class traits>
basic_ostream<charT, traits>&
operator<<(basic_ostream<charT, traits>& os, const year& y);
template<class charT, class traits, class Alloc = allocator<charT>>
basic_istream<charT, traits>&
from_stream(basic_istream<charT, traits>& is, const charT* fmt,
year& y, basic_string<charT, traits, Alloc>* abbrev = nullptr,
minutes* offset = nullptr);
constexpr chrono::year operator""y(unsigned long long y) noexcept;