This page is a snapshot from the LWG issues list, see the Library Active Issues List for more information and the meaning of C++20 status.
3231.year_month_day_last::day specification does not cover !ok() values
Section: 30.8.15.2 [time.cal.ymdlast.members] Status: C++20 Submitter: Tomasz Kamiński Opened: 2019-06-29 Last modified: 2021-02-25
Priority: 0
View all issues with C++20 status.
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 30.8.15.2 [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.: 30.8.14.2 [time.cal.ymd.members] p18, 30.8.16.2 [time.cal.ymwd.members] p19, 30.8.17.2 [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 30.8.15.2 [time.cal.ymdlast.members] as indicated:
constexpr chrono::day day() const noexcept;-13- Returns: If
-14- [Note: This value may be computed on demand. — end note]ok()istrue, returns a Adayrepresenting the last day of the (year, month) pair represented by*this. Otherwise the returned value is unspecified.
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4