meisenbraun@… — Sat, 19 Mar 2016 18:20:16 GMT

Code to expose the issue:

#include <boost/date_time/local_time/local_time.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>
#include <iostream>
#include <cmath>
int main(int argc, char** argv )
{
    using namespace boost;
    using namespace boost::gregorian;
    using namespace boost::local_time;
    using namespace boost::posix_time;
    ptime sourceTime;
    tz_database db;
    db.load_from_file("date_time_zonespec.csv");
    time_zone_ptr localTZ = db.time_zone_from_region("America/Chicago");
    const unsigned int n = 26 * 60 +120;
    date preDST(2016,Mar,12);
    time_duration offset0 = hours(0);
    local_date_time dt0(preDST, offset0, localTZ, local_date_time::NOT_DATE_TIME_ON_ERROR);
    date date2 = preDST + days(std::floor(n/(24*60)));
    time_duration offset1 = minutes(n%(24*60));
    local_date_time dt1(date2, offset1, localTZ, local_date_time::NOT_DATE_TIME_ON_ERROR);
    time_duration offset2 = minutes(n);
    local_date_time dt2(preDST, offset2, localTZ, local_date_time::NOT_DATE_TIME_ON_ERROR);
    std::cout << "DT 0: " << dt0 << std::endl;
    std::cout << "DT 1: " << dt1 << std::endl; // 04:00:00 CDT reported, 05:00:00 CDT expected
    std::cout << "DT 2: " << dt2 << std::endl; // 05:00:00 CDT reported
}

Boost C++ Libraries: Ticket #4771: DST calculation inconsistencies