From Jason Turner

[time.cal.ymwdlast]

C++17 → C++20 6.9 KB 230 lines
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tmp/tmpprgeqjcn/{from.md → to.md} RENAMED
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+ ### Class `year_month_weekday_last` <a id="time.cal.ymwdlast">[[time.cal.ymwdlast]]</a>
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+
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+ #### Overview <a id="time.cal.ymwdlast.overview">[[time.cal.ymwdlast.overview]]</a>
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+
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+ ``` cpp
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+ namespace std::chrono {
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+ class year_month_weekday_last {
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+ chrono::year y_; // exposition only
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+ chrono::month m_; // exposition only
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+ chrono::weekday_last wdl_; // exposition only
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+
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+ public:
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+ constexpr year_month_weekday_last(const chrono::year& y, const chrono::month& m,
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+ const chrono::weekday_last& wdl) noexcept;
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+
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+ constexpr year_month_weekday_last& operator+=(const months& m) noexcept;
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+ constexpr year_month_weekday_last& operator-=(const months& m) noexcept;
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+ constexpr year_month_weekday_last& operator+=(const years& y) noexcept;
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+ constexpr year_month_weekday_last& operator-=(const years& y) noexcept;
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+
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+ constexpr chrono::year year() const noexcept;
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+ constexpr chrono::month month() const noexcept;
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+ constexpr chrono::weekday weekday() const noexcept;
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+ constexpr chrono::weekday_last weekday_last() const noexcept;
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+
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+ constexpr operator sys_days() const noexcept;
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+ constexpr explicit operator local_days() const noexcept;
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+ constexpr bool ok() const noexcept;
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+ };
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+ }
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+ ```
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+
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+ `year_month_weekday_last` represents a specific year, month, and last
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+ weekday of the month. `year_month_weekday_last` is a field-based time
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+ point with a resolution of `days`, except that it is restricted to
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+ pointing to the last weekday of a year and month.
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+
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+ [*Note 1*: `year_month_weekday_last` supports `years`- and
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+ `months`-oriented arithmetic, but not `days`-oriented arithmetic. For
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+ the latter, there is a conversion to `sys_days`, which efficiently
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+ supports `days`-oriented arithmetic. — *end note*]
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+
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+ `year_month_weekday_last` meets the *Cpp17EqualityComparable* (
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+ [[cpp17.equalitycomparable]]) requirements.
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+
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+ `year_month_weekday_last` is a trivially copyable and standard-layout
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+ class type.
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+
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+ #### Member functions <a id="time.cal.ymwdlast.members">[[time.cal.ymwdlast.members]]</a>
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+
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+ ``` cpp
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+ constexpr year_month_weekday_last(const chrono::year& y, const chrono::month& m,
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+ const chrono::weekday_last& wdl) noexcept;
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+ ```
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+
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+ *Effects:* Initializes `y_` with `y`, `m_` with `m`, and `wdl_` with
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+ `wdl`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday_last& operator+=(const months& m) noexcept;
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+ ```
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+
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+ *Constraints:* If the argument supplied by the caller for the `months`
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+ parameter is convertible to `years`, its implicit conversion sequence to
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+ `years` is worse than its implicit conversion sequence to `months`
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+ [[over.ics.rank]].
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+
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+ *Effects:* `*this = *this + m`.
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+
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+ *Returns:* `*this`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday_last& operator-=(const months& m) noexcept;
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+ ```
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+
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+ *Constraints:* If the argument supplied by the caller for the `months`
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+ parameter is convertible to `years`, its implicit conversion sequence to
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+ `years` is worse than its implicit conversion sequence to `months`
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+ [[over.ics.rank]].
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+
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+ *Effects:* `*this = *this - m`.
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+
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+ *Returns:* `*this`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday_last& operator+=(const years& y) noexcept;
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+ ```
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+
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+ *Effects:* `*this = *this + y`.
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+
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+ *Returns:* `*this`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday_last& operator-=(const years& y) noexcept;
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+ ```
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+
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+ *Effects:* `*this = *this - y`.
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+
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+ *Returns:* `*this`.
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+
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+ ``` cpp
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+ constexpr chrono::year year() const noexcept;
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+ ```
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+
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+ *Returns:* `y_`.
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+
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+ ``` cpp
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+ constexpr chrono::month month() const noexcept;
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+ ```
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+
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+ *Returns:* `m_`.
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+
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+ ``` cpp
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+ constexpr chrono::weekday weekday() const noexcept;
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+ ```
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+
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+ *Returns:* `wdl_.weekday()`.
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+
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+ ``` cpp
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+ constexpr chrono::weekday_last weekday_last() const noexcept;
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+ ```
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+
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+ *Returns:* `wdl_`.
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+
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+ ``` cpp
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+ constexpr operator sys_days() const noexcept;
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+ ```
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+
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+ *Returns:* If `ok() == true`, returns a `sys_days` that represents the
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+ last `weekday()` of `year()/month()`. Otherwise the returned value is
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+ unspecified.
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+
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+ ``` cpp
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+ constexpr explicit operator local_days() const noexcept;
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+ ```
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+
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+ *Returns:* `local_days{sys_days{*this}.time_since_epoch()}`.
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+
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+ ``` cpp
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+ constexpr bool ok() const noexcept;
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+ ```
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+
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+ *Returns:* `y_.ok() && m_.ok() && wdl_.ok()`.
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+
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+ #### Non-member functions <a id="time.cal.ymwdlast.nonmembers">[[time.cal.ymwdlast.nonmembers]]</a>
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+
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+ ``` cpp
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+ constexpr bool operator==(const year_month_weekday_last& x,
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+ const year_month_weekday_last& y) noexcept;
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+ ```
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+
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+ *Returns:*
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+
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+ ``` cpp
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+ x.year() == y.year() && x.month() == y.month() && x.weekday_last() == y.weekday_last()
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+ ```
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+
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+ ``` cpp
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+ constexpr year_month_weekday_last
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+ operator+(const year_month_weekday_last& ymwdl, const months& dm) noexcept;
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+ ```
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+
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+ *Constraints:* If the argument supplied by the caller for the `months`
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+ parameter is convertible to `years`, its implicit conversion sequence to
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+ `years` is worse than its implicit conversion sequence to `months`
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+ [[over.ics.rank]].
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+
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+ *Returns:* `(ymwdl.year() / ymwdl.month() + dm) / ymwdl.weekday_last()`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday_last
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+ operator+(const months& dm, const year_month_weekday_last& ymwdl) noexcept;
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+ ```
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+
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+ *Constraints:* If the argument supplied by the caller for the `months`
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+ parameter is convertible to `years`, its implicit conversion sequence to
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+ `years` is worse than its implicit conversion sequence to `months`
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+ [[over.ics.rank]].
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+
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+ *Returns:* `ymwdl + dm`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday_last
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+ operator-(const year_month_weekday_last& ymwdl, const months& dm) noexcept;
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+ ```
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+
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+ *Constraints:* If the argument supplied by the caller for the `months`
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+ parameter is convertible to `years`, its implicit conversion sequence to
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+ `years` is worse than its implicit conversion sequence to `months`
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+ [[over.ics.rank]].
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+
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+ *Returns:* `ymwdl + (-dm)`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday_last
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+ operator+(const year_month_weekday_last& ymwdl, const years& dy) noexcept;
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+ ```
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+
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+ *Returns:* `{ymwdl.year()+dy, ymwdl.month(), ymwdl.weekday_last()}`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday_last
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+ operator+(const years& dy, const year_month_weekday_last& ymwdl) noexcept;
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+ ```
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+
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+ *Returns:* `ymwdl + dy`.
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+
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+ ``` cpp
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+ constexpr year_month_weekday_last
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+ operator-(const year_month_weekday_last& ymwdl, const years& dy) noexcept;
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+ ```
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+
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+ *Returns:* `ymwdl + (-dy)`.
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+
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+ ``` cpp
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+ template<class charT, class traits>
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+ basic_ostream<charT, traits>&
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+ operator<<(basic_ostream<charT, traits>& os, const year_month_weekday_last& ymwdl);
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+ ```
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+
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+ *Effects:* Equivalent to:
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+
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+ ``` cpp
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+ return os << format(os.getloc(), STATICALLY-WIDEN<charT>("{}/{}/{}"),
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+ ymwdl.year(), ymwdl.month(), ymwdl.weekday_last());
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+ ```
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+