KDDateTime does not handle time zone strings correctly

[jtjbrady]

I do not believe KDDateTime handles time zones strings for fractional time zones correctly.

The code in question is:

        setTimeSpec(Qt::OffsetFromUTC);
        const int pos = timeZone.indexOf(QLatin1Char(':'));
        if (pos > 0) {
#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
            const int hours = timeZone.leftRef(pos).toInt();
            const int minutes = timeZone.midRef(pos + 1).toInt();
#else
            const QStringView timeZoneView(timeZone);
            const int hours = timeZoneView.first(pos).toInt();
            const int minutes = timeZoneView.sliced(pos + 1).toInt();
#endif
            const int offset = hours * 3600 + minutes * 60;
            setOffsetFromUtc(offset);
        }

Fractional time zones which is what this issue is about. There are only a few in use and even fewer which are a negative UTC offset. Looking at the example of Newfoundland, Canada which has an offset of -3:30/-2:30 depending on daylight savings and looking specifically at -3:30:

The hours extracted by the above code would be -3.
The minutes extracted by the above code would be + 30.

The line:
const int offset = hours * 3600 + minutes * 60;
Would give an offset of -3 * 3600 or - 10800, plus 1800, giving an offset of -9000 seconds, or 2 1/2 hours instead of 3 1/2.