QVector in Qt5 still requires default constructible types

template <typename T>
typename QVector<T>::iterator QVector<T>::insert(iterator before, size_type n, const T &t)
{
    Q_ASSERT_X(isValidIterator(before),  "QVector::insert", "The specified iterator argument 'before' is invalid");

    const auto offset = std::distance(d->begin(), before);
    if (n != 0) {
        const T copy(t);
        if (!isDetached() || d->size + n > int(d->alloc))
            realloc(d->size + n, QArrayData::Grow);
        if (!QTypeInfoQuery<T>::isRelocatable) {
            T *b = d->end();
            T *i = d->end() + n;
            while (i != b)
                new (--i) T; // <-- the problem right here
            i = d->end();
            T *j = i + n;
            b = d->begin() + offset;
            while (i != b)
                *--j = *--i; // ???
            i = b+n;
            while (i != b)
                *--i = copy;
        } else {
            T *b = d->begin() + offset;
            T *i = b + n;
            memmove(static_cast<void *>(i), static_cast<const void *>(b), (d->size - offset) * sizeof(T));
            while (i != b)
                new (--i) T(copy);
        }
        d->size += n;
    }
    return d->begin() + offset;
}