https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97613
Bug ID: 97613
Summary: chrono::year_month_weekday cast to sys_days : return
bad value if index() == 0
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: faithandbrave at gmail dot com
Target Milestone: ---
#include <iostream>
#include <chrono>
namespace chrono = std::chrono;
using namespace std::chrono_literals;
int main()
{
// 1
chrono::sys_days date1 = 2020y/3/chrono::Sunday[1];
assert(chrono::year_month_day{date1} == 2020y/3/1);
// 2
chrono::sys_days date2 = 2020y/3/chrono::Sunday[2];
assert(chrono::year_month_day{date2} == 2020y/3/8);
// 3
chrono::sys_days date3 = 2020y/3/chrono::Sunday[0];
assert(chrono::year_month_day{date3} == 2020y/2/23);
}
Assertion failed the program's No.3 patten.
GCC 11 (trunk) returns `30297y/March/14d`. Clang (libc++) is OK.
See the specification:
> 27.8.16.2 [time.cal.ymwd.members]
> If index() is 0 the returned sys_days represents the date 7 days prior to the
> first weekday() of year()/month().
