From [Signals & Slots|https://doc.qt.io/qt-5/signalsandslots.html]

You can connect as many signals as you want to a single slot, and a signal can be connected to as many slots as you need. It is even possible to connect a signal directly to another signal. (This will emit the second signal immediately whenever the first is emitted.)

The attached case connects signals to signals, but the signals are not propagated.  Class1 has a time that emits a timer signal every second.  That signal is correctly serviced by Class1.

Class1 is created by Class2.  Class2 connects Class1's clicked signal to Class2's clicked signal, but it does not get invoked.