qtbase: QDateTime latest patch requires compiling with c++17 for no good reason

I'm talking about this simple test recently pushed in kde/5.15 branch if (qint64 r; Q_UNLIKELY(add_overflow(jd, ndays, &r))) https://invent.kde.org/qt/qt/qtbase/-/blob/kde/5.15/src/corelib/time/qdatetime.cpp#L1433

This is the one and only line in that branch that requires c++17, I believe the patch could be rewritten with a more conventional if statement, what do you think?

qint64 r;
if (Q_UNLIKELY(add_overflow(jd, ndays, &r)))