Why QHash::iterator's operator+() was declared obsolet in 5.15?

[Kofr]

And how to substitute correctly?

[Bonnie]

You can check the documentation yourself:
https://doc.qt.io/qt-5/qhash-iterator-obsolete.html#operator-2b

This operator is deprecated in order to align with std::unordered_map functionality.

So I don't think there is any substitution since this function is removed on purpose.
I think they just want to disable all the "backward" iterating functions of QHash (operator+() accepts negative values).
You can use QMap instead, or calling operator++() multiple times, as what operator+() with a positive value actually does..

[Christian Ehrlicher]

The function simply makes no sense - QHash is unordered so what do you want from this operator?