Reset history states when (re)starting state machine

State saved in QHistoryState should not be persistent between
state machine starts/stops.

Task-number: QTBUG-8842
Reviewed-by: Eskil Abrahamsen Blomfeldt

2 files changed, 13 insertions, 0 deletions

diff --git a/src/corelib/statemachine/qstatemachine.cpp b/src/corelib/statemachine/qstatemachine.cpp
index bd7e6261ec..9d5c49f7b4 100644
--- a/src/corelib/statemachine/qstatemachine.cpp
+++ b/src/corelib/statemachine/qstatemachine.cpp
@@ -1175,6 +1175,16 @@ void QStateMachinePrivate::removeStartState()
     _startState = 0;
 }
 
+void QStateMachinePrivate::clearHistory()
+{
+    Q_Q(QStateMachine);
+    QList<QHistoryState*> historyStates = qFindChildren<QHistoryState*>(q);
+    for (int i = 0; i < historyStates.size(); ++i) {
+        QHistoryState *h = historyStates.at(i);
+        QHistoryStatePrivate::get(h)->configuration.clear();
+    }
+}
+
 void QStateMachinePrivate::_q_start()
 {
     Q_Q(QStateMachine);
@@ -1186,6 +1196,7 @@ void QStateMachinePrivate::_q_start()
     internalEventQueue.clear();
     qDeleteAll(externalEventQueue);
     externalEventQueue.clear();
+    clearHistory();
 
 #ifdef QSTATEMACHINE_DEBUG
     qDebug() << q << ": starting";
diff --git a/src/corelib/statemachine/qstatemachine_p.h b/src/corelib/statemachine/qstatemachine_p.h
index 0fead5d35c..5e1015fc37 100644
--- a/src/corelib/statemachine/qstatemachine_p.h
+++ b/src/corelib/statemachine/qstatemachine_p.h
@@ -126,6 +126,8 @@ public:
     QState *startState();
     void removeStartState();
 
+    void clearHistory();
+
     void microstep(QEvent *event, const QList<QAbstractTransition*> &transitionList);
     bool isPreempted(const QAbstractState *s, const QSet<QAbstractTransition*> &transitions) const;
     QSet<QAbstractTransition*> selectTransitions(QEvent *event) const;