Make sure QStateMachine stops when it's told to

If QStateMachine::stop() was called by an event test or while
transitioning to another state, the state machine could end up
in an inconsistent internal state (stop==true, but the stopped()
signal was not emitted). This also caused the machine to behave
incorrectly if it was then restarted (it would immediately stop
upon receiving the first event).

Solution: Move the stop-handling after the event processing loop,
so that it always takes precedence over other possible reasons
for exiting the loop (event queues exhausted, final state
entered).

Task-number: QTBUG-16463
Reviewed-by: Eskil Abrahamsen Blomfeldt

1 files changed, 5 insertions, 2 deletions

diff --git a/src/corelib/statemachine/qstatemachine.cpp b/src/corelib/statemachine/qstatemachine.cpp
index 392c45d8c7..b2af5ca961 100644
--- a/src/corelib/statemachine/qstatemachine.cpp
+++ b/src/corelib/statemachine/qstatemachine.cpp
@@ -1245,9 +1245,7 @@ void QStateMachinePrivate::_q_process()
 #endif
     while (processing) {
         if (stop) {
-            stop = false;
             processing = false;
-            stopProcessingReason = Stopped;
             break;
         }
         QSet<QAbstractTransition*> enabledTransitions;
@@ -1299,6 +1297,11 @@ void QStateMachinePrivate::_q_process()
 #ifdef QSTATEMACHINE_DEBUG
     qDebug() << q << ": finished the event processing loop";
 #endif
+    if (stop) {
+        stop = false;
+        stopProcessingReason = Stopped;
+    }
+
     switch (stopProcessingReason) {
     case EventQueueEmpty:
         break;