QObjectUserData was removed in Qt 5.14

[magiruuvelvet]

The alternative PROPERTY uses QVariant which doesn't support raw pointers. 😭 The undocumented USERDATA used raw pointers which were a nice hack to transfer data between unrelated functions and objects.

/usr/include/qt5/QtCore/qvariant.h:497:12: note: 'QVariant' has been explicitly marked deleted here
    inline QVariant(void *) = delete;

Just replacing all function calls didn't went so well. To fix this issue I need an additional layer of wrapping the pointer into a class and use that for QVariant.

This is what you get for using undocumented private APIs -> pain and suffering.