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Section: 29.8.15.2 [time.cal.ymdlast.members] Status: C++20 Submitter: Tomasz Kamiński Opened: 2019-06-29 Last modified: 2021-02-25
Priority: 0
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Discussion:
The current specification of the year_month_day_last::day
function does not cover the behaviour in the situation when year_month_day_last
value is not ok(). To illustrate the sentence from
29.8.15.2 [time.cal.ymdlast.members] p13:
A
dayrepresenting the last day of the (year,month) pair represented by*this.
is unclear in the situation when month member has
!ok value, e.g. what is last day of 14th month of 2019.
ymdl.day() (and by
consequence conversion to sys_days/local_days)
unspecified if ymdl.ok() is false. This make is
consistent with rest of the library, that produces unspecified values in
similiar situation, e.g.: 29.8.14.2 [time.cal.ymd.members] p18,
29.8.16.2 [time.cal.ymwd.members] p19,
29.8.17.2 [time.cal.ymwdlast.members] p14.
[2019-07 Issue Prioritization]
Status to Tentatively Ready after five positive votes on the reflector.
Proposed resolution:
This wording is relative to N4820.
Modify 29.8.15.2 [time.cal.ymdlast.members] as indicated:
constexpr chrono::day day() const noexcept;-13- Returns: If ok() is true, returns a
-14- [Note: This value may be computed on demand. — end note]Aday representing the last day of the (year, month) pair represented by *this. Otherwise the returned value is unspecified.