can't include moc generated code

I have a class using Q_PRIVATE_SLOT and unsurprisingly moc doesn't know about the private class.

Usually with CMake I would include the moc generated .cpp file but this doesn't seem to be possible with qbs as it asserts in src/corelib/buildgraph/rulenode.cpp line 129:

QBS_CHECK(parent->transformer->inputs.contains(artifact))