gracefully handle deletion of transition's target state

4 files changed, 30 insertions, 4 deletions

diff --git a/src/corelib/statemachine/qabstracttransition.cpp b/src/corelib/statemachine/qabstracttransition.cpp
index 696da9f..6ddb416 100644
--- a/src/corelib/statemachine/qabstracttransition.cpp
+++ b/src/corelib/statemachine/qabstracttransition.cpp
@@ -273,7 +273,13 @@ void QAbstractTransition::setTargetState(QAbstractState* target)
 QList<QAbstractState*> QAbstractTransition::targetStates() const
 {
     Q_D(const QAbstractTransition);
-    return d->targetStates;
+    QList<QAbstractState*> result;
+    for (int i = 0; i < d->targetStates.size(); ++i) {
+        QAbstractState *target = d->targetStates.at(i);
+        if (target)
+            result.append(target);
+    }
+    return result;
 }
 
 /*!
@@ -285,13 +291,19 @@ void QAbstractTransition::setTargetStates(const QList<QAbstractState*> &targets)
 
     for (int i=0; i<targets.size(); ++i) {
         QAbstractState *target = targets.at(i);
+        if (!target) {
+            qWarning("QAbstractTransition::setTargetStates: target state(s) cannot be null");
+            return;
+        }
         if (target->machine() != 0 && target->machine()->rootState() == target) {
             qWarning("QAbstractTransition::setTargetStates: root state cannot be target of transition");
             return;
         }
     }
 
-    d->targetStates = targets;
+    d->targetStates.clear();
+    for (int i = 0; i < targets.size(); ++i)
+        d->targetStates.append(targets.at(i));
 }
 
 /*!
diff --git a/src/corelib/statemachine/qabstracttransition_p.h b/src/corelib/statemachine/qabstracttransition_p.h
index b4e1c88..eb0ec21 100644
--- a/src/corelib/statemachine/qabstracttransition_p.h
+++ b/src/corelib/statemachine/qabstracttransition_p.h
@@ -58,6 +58,7 @@
 #endif
 
 #include <QtCore/qlist.h>
+#include <QtCore/qpointer.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -83,7 +84,7 @@ public:
     QState *sourceState() const;
     QStateMachine *machine() const;
 
-    QList<QAbstractState*> targetStates;
+    QList<QPointer<QAbstractState> > targetStates;
 
 #ifndef QT_NO_ANIMATION
     QList<QAbstractAnimation*> animations;
diff --git a/src/corelib/statemachine/qstate.cpp b/src/corelib/statemachine/qstate.cpp
index 63a0a69..5f61865 100644
--- a/src/corelib/statemachine/qstate.cpp
+++ b/src/corelib/statemachine/qstate.cpp
@@ -312,7 +312,7 @@ QAbstractTransition *QState::addTransition(QAbstractTransition *transition)
         return 0;
     }
 
-    const QList<QAbstractState*> &targets = QAbstractTransitionPrivate::get(transition)->targetStates;
+    const QList<QPointer<QAbstractState> > &targets = QAbstractTransitionPrivate::get(transition)->targetStates;
     for (int i = 0; i < targets.size(); ++i) {
         QAbstractState *t = targets.at(i);
         if (!t) {
diff --git a/tests/auto/qstatemachine/tst_qstatemachine.cpp b/tests/auto/qstatemachine/tst_qstatemachine.cpp
index fa49ecb..dbc67d1 100644
--- a/tests/auto/qstatemachine/tst_qstatemachine.cpp
+++ b/tests/auto/qstatemachine/tst_qstatemachine.cpp
@@ -106,6 +106,7 @@ private slots:
     void historyStates();
     void startAndStop();
     void targetStateWithNoParent();
+    void targetStateDeleted();
     void transitionToRootState();
     void transitionEntersParent();
     
@@ -1940,6 +1941,18 @@ void tst_QStateMachine::targetStateWithNoParent()
     QCOMPARE(machine.error(), QStateMachine::NoCommonAncestorForTransitionError);
 }
 
+void tst_QStateMachine::targetStateDeleted()
+{
+    QStateMachine machine;
+    QState *s1 = new QState(machine.rootState());
+    s1->setObjectName("s1");
+    QState *s2 = new QState(machine.rootState());
+    QAbstractTransition *trans = s1->addTransition(s2);
+    delete s2;
+    QCOMPARE(trans->targetState(), (QAbstractState*)0);
+    QVERIFY(trans->targetStates().isEmpty());
+}
+
 void tst_QStateMachine::defaultGlobalRestorePolicy()
 {
     QStateMachine machine;