template<typename T>
concept QStringConvertible = std::convertible_to<T, QString>;

// small adjustments to how QList does IfIsInputIterator
template <typename Iterator>
using IfIsInputIterator =
    typename std::enable_if<
        std::is_convertible<
            typename std::iterator_traits<Iterator>::iterator_category,
            std::input_iterator_tag
            >::value
            && !QStringConvertible<Iterator> // added this line to the original QList implementation - without this, QStringListTest("abc", "def") calls the InputIterator cTor
        ,
        bool>::type;

class QStringListTest : public QList<QString>
{
public:
    template<QStringConvertible... Args>
    QStringListTest(Args... args) : QList<QString>{std::forward<Args>(args)...} { // takes an arbitrary amount of QString convertibles
        qDebug() << "args constructor called";

        for (const auto& entry : *this) {
            qDebug() << entry;
        }
    }

    // this comes directly from QList
    template<typename InputIterator>
    using if_input_iterator = IfIsInputIterator<InputIterator>;

    template <typename InputIterator, if_input_iterator<InputIterator> = true>
    QStringListTest(InputIterator i1, InputIterator i2) : QList<QString>(i1, i2) { // does not get called anymore from QStringListTest("abc", "def") now where it has been before
        qDebug() << "input iterator constructor called";
    }
};