Since Connection can be copied, one copy could be used for
disconnecting, but the other's d_ptr wouldn't get updated and would
continue to report as still connected.
This patch fixes that by making it check the internal state. That is
only done after d_ptr is already known to be non-null. Unfortunately,
that is the common path:
if (connect(sender, &Sender::signal, [] {}))
will call an out-of-line function. I don't see a way out.
Task-number: QTBUG-46213
Change-Id: I66a35ce5f88941f29aa6ffff13dfb45dca68a350
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
b2be272d35