Register QObjectList type conditionally (#339)

FIX: #338

Author: JulienMaille

src/PythonQt.cpp

@@ -121,7 +121,11 @@ void PythonQt::init(int flags, const QByteArray& pythonQtModuleName)
 
     PythonQtMethodInfo::addParameterTypeAlias("QObjectList", "QList<QObject*>");
     qRegisterMetaType<QList<QObject*>>("QList<void*>");
-    qRegisterMetaType<QObjectList>("QObjectList");
+    // QObjectList might already be registered by other modules (e.g. QtScript) or under different type names.
+    // To avoid conflicts or warnings, only register it if it is currently unknown.
+    if (QMetaType::type("QObjectList") == QMetaType::UnknownType) {
+      qRegisterMetaType<QObjectList>("QObjectList");
+    }
     qRegisterMetaType<QList<QObject*>>("QList<QObject*>");
     if (QT_POINTER_SIZE == 8) {
       qRegisterMetaType<quint64>("size_t");