========================C++============================
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QtQml/QtQml>
#include <QDebug>

class Foo: public QObject {
    Q_OBJECT
    Q_ENUMS(FooEnum)
public:
    enum FooEnum {
        A,
        B
    };
};

class Bar: public QObject {
    Q_OBJECT
public:
public slots:
    void notWorkingSlotWithEnumArg(Foo::FooEnum slotValue)
    {
        qDebug() << "notWorkingSlotWithEnumArg slot worked with value:" << slotValue;
    }
};


int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    qmlRegisterUncreatableType<Foo>("Foo", 1, 0, "Foo"," prefix for enum");
    qmlRegisterType<Bar>("Bar", 1, 0, "Bar");
    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:///main.qml")));

    return app.exec();
}

#include "main.moc"

========================C++============================
========================Qml============================


import QtQuick 2.2
import QtQuick.Window 2.1
import Bar 1.0
import Foo 1.0

Window {
    visible: true
    width: 360
    height: 360

    MouseArea {
        anchors.fill: parent
        onClicked: {
            bar.notWorkingSlotWithEnumArg(Foo.A)
            Qt.quit();
        }

    }

    Bar {
        id: bar
    }
}

========================Qml============================