QQmlProperty: fix signal handler warning

It should only be emitted if we find a signal of that name.

Pick-to: 6.5
Fixes: QTBUG-118710
Change-Id: I15cf92c03dd7b46805e5a69078ca2beb6c862293
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit 9d10b79566)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit 6c0489e65f)

src/qml/qml/qqmlproperty.cpp

@@ -428,13 +428,14 @@ void QQmlPropertyPrivate::initProperty(QObject *obj, const QString &name,
         if (result != end)
             *result = result->toUpper();
 
-        qWarning()
-                << terminalString
-                << "is not a properly capitalized signal handler name."
-                << handlerName
-                << "would be correct.";
-        if (findSignalInMetaObject(signalName.toUtf8()))
+        if (findSignalInMetaObject(signalName.toUtf8())) {
+            qWarning()
+                    << terminalString
+                    << "is not a properly capitalized signal handler name."
+                    << handlerName
+                    << "would be correct.";
             return;
+        }
     }
 
     if (ddata && ddata->propertyCache) {

tests/auto/qml/qqmlproperty/data/propertyStartsWithOn.qml

@@ -0,0 +1,9 @@
+import QtQml
+
+QtObject {
+    id: root
+    property int onlineStatus
+    property Binding b: Binding {
+        root.onlineStatus: 12
+    }
+}

tests/auto/qml/qqmlproperty/tst_qqmlproperty.cpp

@@ -222,6 +222,8 @@ private slots:
 
     void invalidateQPropertyChangeTriggers();
 
+    void propertyStartsWithOn();
+
 private:
     QQmlEngine engine;
 };
@@ -2589,6 +2591,18 @@ void tst_qqmlproperty::invalidateQPropertyChangeTriggers()
     }));
 }
 
+void tst_qqmlproperty::propertyStartsWithOn()
+{
+    QTest::failOnWarning("\"onlineStatus\" is not a properly capitalized signal handler name. "
+                         "\"onLineStatus\" would be correct.");
+    QQmlEngine engine;
+    QQmlComponent component(&engine, testFileUrl("propertyStartsWithOn.qml"));
+    QVERIFY2(component.isReady(), qPrintable(component.errorString()));
+    QScopedPointer<QObject> root(component.create());
+    QVERIFY(!root.isNull());
+    QCOMPARE(root->property("onlineStatus").toInt(), 12);
+}
+
 QTEST_MAIN(tst_qqmlproperty)
 
 #include "tst_qqmlproperty.moc"