Cannot create global QFileSystemWatcher object

 #include <QApplication>
#include <QFileSystemWatcher>


QFileSystemWatcher watcher;

int main(int argc, char* argv[])
{
    QApplication app(argc, argv);

    watcher.addPath("C:/QtTest");

    QStringList directoryList = watcher.directories();
    Q_FOREACH(QString directory, directoryList)
            qDebug() << "Directory name" << directory <<"\n";

    QObject::connect(&watcher, &QFileSystemWatcher::directoryChanged, [] (QString const &) {
        QMessageBox::information(nullptr, "Directory Modified", "Your Directory is modified");
    });

    return app.exec();
}