std::chrono::day::day - std::chrono::day::day
day() = default; (1) (since C++20)
explicit constexpr day( unsigned d ) noexcept; (2) (since
C++20)
Constructs a day object.
1) Default constructor leaves the day value uninitialized.
2) If d <= 255, constructs a day object holding the day value d. Otherwise
the value
held is unspecified.