Gracefully handle early deregistration of objects

When an object is deregistered before the signal handler got
initializated, we asserted. Now, we check for this case and skip the
signal handler removal when it wasn't set up yet.

Change-Id: I1edb5fb4f1429e6c69c6c41baabd3d30a4b6fe10
Task-number: QTBUG-60250
Reviewed-by: Kai Dohmen <psykai1993@googlemail.com>
Reviewed-by: Konstantin Tokarev <annulen@yandex.ru>
(cherry picked from commit 446978af11ab886d734ca3972dcd73f847df9fbc)

3 files changed, 22 insertions, 2 deletions

diff --git a/src/webchannel/qmetaobjectpublisher.cpp b/src/webchannel/qmetaobjectpublisher.cpp
index 85a9b35..8fc54a4 100644
--- a/src/webchannel/qmetaobjectpublisher.cpp
+++ b/src/webchannel/qmetaobjectpublisher.cpp
@@ -448,8 +448,12 @@ void QMetaObjectPublisher::objectDestroyed(const QObject *object)
     Q_ASSERT(removed);
     Q_UNUSED(removed);
 
-    signalHandler.remove(object);
-    signalToPropertyMap.remove(object);
+    // only remove from handler when we initialized the property updates
+    // cf: https://bugreports.qt.io/browse/QTBUG-60250
+    if (propertyUpdatesInitialized) {
+        signalHandler.remove(object);
+        signalToPropertyMap.remove(object);
+    }
     pendingPropertyUpdates.remove(object);
 }
 
diff --git a/tests/auto/webchannel/tst_webchannel.cpp b/tests/auto/webchannel/tst_webchannel.cpp
index 2ab820b..95a6160 100644
--- a/tests/auto/webchannel/tst_webchannel.cpp
+++ b/tests/auto/webchannel/tst_webchannel.cpp
@@ -317,6 +317,21 @@ void TestWebChannel::testDeregisterObjects()
     emit testObject.sig1();
 }
 
+void TestWebChannel::testDeregisterObjectAtStart()
+{
+    QWebChannel channel;
+    QVERIFY(channel.registeredObjects().isEmpty());
+
+    TestObject testObject;
+    testObject.setObjectName("myTestObject");
+
+    channel.registerObject(testObject.objectName(), &testObject);
+    QCOMPARE(channel.registeredObjects().size(), 1);
+
+    channel.deregisterObject(&testObject);
+    QVERIFY(channel.registeredObjects().isEmpty());
+}
+
 void TestWebChannel::testInfoForObject()
 {
     TestObject obj;
diff --git a/tests/auto/webchannel/tst_webchannel.h b/tests/auto/webchannel/tst_webchannel.h
index 94dccf5..1f36fbe 100644
--- a/tests/auto/webchannel/tst_webchannel.h
+++ b/tests/auto/webchannel/tst_webchannel.h
@@ -290,6 +290,7 @@ signals:
 private slots:
     void testRegisterObjects();
     void testDeregisterObjects();
+    void testDeregisterObjectAtStart();
     void testInfoForObject();
     void testInvokeMethodConversion();
     void testSetPropertyConversion();