[mushiake]

smoke/kde was supposed to be contender for gobject-introspection, however it is barely maintained.

It is only(?) used by common lisp[0].

And there was claro[1].

[0]https://github.com/Shinmera/qtools

[1]https://github.com/Araq/Claro

[daurnimator]

It too seems to be stuck on Qt4.

Only python bindings seem to have made it up to Qt5.