The following code produces a quite unexpected binding loop warning:

Button {
    action: Action { }
    checkable: action.checkable || true
}

(Note that the || true bit can be anything that is different from the Action's checkable value.)

This seems to happen because when the Button's checkable is evaluated, it updates the action's checkable, which triggers a reevaluation of the binding on checkable.

I am not entirely sure what the correct solution is here, however to me syncing the checkable state seems rather unexpected and I would expect it to behave like the text or icon properties.