don't add signal transition if target is null or signal doesn't exist

2 files changed, 30 insertions, 2 deletions

diff --git a/src/corelib/statemachine/qstate.cpp b/src/corelib/statemachine/qstate.cpp
index acee27d..4d12219 100644
--- a/src/corelib/statemachine/qstate.cpp
+++ b/src/corelib/statemachine/qstate.cpp
@@ -346,6 +346,15 @@ QSignalTransition *QState::addTransition(QObject *sender, const char *signal,
         qWarning("QState::addTransition: signal cannot be null");
         return 0;
     }
+    if (!target) {
+        qWarning("QState::addTransition: cannot add transition to null state");
+        return 0;
+    }
+    if (*signal && sender->metaObject()->indexOfSignal(signal+1) == -1) {
+        qWarning("QState::addTransition: no such signal %s::%s",
+                 sender->metaObject()->className(), signal+1);
+        return 0;
+    }
     QSignalTransition *trans = new QSignalTransition(sender, signal, QList<QAbstractState*>() << target);
     addTransition(trans);
     return trans;
diff --git a/tests/auto/qstatemachine/tst_qstatemachine.cpp b/tests/auto/qstatemachine/tst_qstatemachine.cpp
index 9b7bff3..f7fce94 100644
--- a/tests/auto/qstatemachine/tst_qstatemachine.cpp
+++ b/tests/auto/qstatemachine/tst_qstatemachine.cpp
@@ -1579,9 +1579,28 @@ void tst_QStateMachine::signalTransitions()
     {
         QStateMachine machine;
         QState *s0 = new QState(machine.rootState());
-        QFinalState *s1 = new QFinalState(machine.rootState());
+        QTest::ignoreMessage(QtWarningMsg, "QState::addTransition: sender cannot be null");
+        QCOMPARE(s0->addTransition(0, SIGNAL(noSuchSignal()), 0), (QObject*)0);
+
         SignalEmitter emitter;
-        s0->addTransition(&emitter, SIGNAL(signalWithNoArg()), s1);
+        QTest::ignoreMessage(QtWarningMsg, "QState::addTransition: signal cannot be null");
+        QCOMPARE(s0->addTransition(&emitter, 0, 0), (QObject*)0);
+
+        QTest::ignoreMessage(QtWarningMsg, "QState::addTransition: cannot add transition to null state");
+        QCOMPARE(s0->addTransition(&emitter, SIGNAL(signalWithNoArg()), 0), (QObject*)0);
+
+        QFinalState *s1 = new QFinalState(machine.rootState());
+        QTest::ignoreMessage(QtWarningMsg, "QState::addTransition: no such signal SignalEmitter::noSuchSignal()");
+        QCOMPARE(s0->addTransition(&emitter, SIGNAL(noSuchSignal()), s1), (QObject*)0);
+
+        {
+            QSignalTransition *trans = s0->addTransition(&emitter, SIGNAL(signalWithNoArg()), s1);
+            QVERIFY(trans != 0);
+            QCOMPARE(trans->sourceState(), s0);
+            QCOMPARE(trans->targetState(), (QAbstractState*)s1);
+            QCOMPARE(trans->senderObject(), (QObject*)&emitter);
+            QCOMPARE(trans->signal(), QByteArray(SIGNAL(signalWithNoArg())));
+        }
 
         QSignalSpy finishedSpy(&machine, SIGNAL(finished()));
         machine.setInitialState(s0);