Exactly zero of the Qt5/6 binding libraries work either with dub (if they have it on there). I have tried them all and each gets errors, VisualD or not.
Therefore, it is smart / safe if a Qt5/6 developer stick with Qt VS tools (if you can get it to function) or simply Qt Creator itself.
This approach is vouched safe by the above. So I will do my GUI in Qt Creator, hopefully not creating a memory leak (lots of QSharedPointers!), but my backend will of course be in D!
:D