Fix visibility of properties in value types

It should be possible to enumerate the properties of value types (gadgets),
in order for things like JSON.stringify(Qt.point(10, 20)) to return something
sensible.

Task-number: QTBUG-43382
Task-number: QTBUG-34878
Change-Id: I3a2c09151ebe97fd97760dfbbf5a4f58e022bc94
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>
Reviewed-by: Robin Burchell <robin.burchell@viroteck.net>

src/qml/qml/qqmlvaluetypewrapper.cpp

@@ -50,6 +50,7 @@
 #include <private/qv4functionobject_p.h>
 #include <private/qv4variantobject_p.h>
 #include <private/qv4alloca_p.h>
+#include <private/qv4objectiterator_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -244,6 +245,34 @@ PropertyAttributes QQmlValueTypeWrapper::query(const Managed *m, String *name)
     return result ? Attr_Data : Attr_Invalid;
 }
 
+void QQmlValueTypeWrapper::advanceIterator(Managed *m, ObjectIterator *it, Value *name, uint *index, Property *p, PropertyAttributes *attributes)
+{
+    name->setM(0);
+    *index = UINT_MAX;
+
+    QQmlValueTypeWrapper *that = static_cast<QQmlValueTypeWrapper*>(m);
+
+    if (QQmlValueTypeReference *ref = that->as<QQmlValueTypeReference>()) {
+        if (!ref->readReferenceValue())
+            return;
+    }
+
+    if (that->d()->propertyCache) {
+        const QMetaObject *mo = that->d()->propertyCache->createMetaObject();
+        const int propertyCount = mo->propertyCount();
+        if (it->arrayIndex < static_cast<uint>(propertyCount)) {
+            Scope scope(that->engine());
+            ScopedString propName(scope, that->engine()->newString(QString::fromUtf8(mo->property(it->arrayIndex).name())));
+            name->setM(propName->d());
+            ++it->arrayIndex;
+            *attributes = QV4::Attr_Data;
+            p->value = that->QV4::Object::get(propName);
+            return;
+        }
+    }
+    QV4::Object::advanceIterator(m, it, name, index, p, attributes);
+}
+
 bool QQmlValueTypeWrapper::isEqual(const QVariant& value)
 {
     if (QQmlValueTypeReference *ref = as<QQmlValueTypeReference>())

src/qml/qml/qqmlvaluetypewrapper_p.h

@@ -99,6 +99,7 @@ public:
     static void put(Managed *m, String *name, const Value &value);
     static bool isEqualTo(Managed *m, Managed *other);
     static PropertyAttributes query(const Managed *, String *name);
+    static void advanceIterator(Managed *m, ObjectIterator *it, Value *name, uint *index, Property *p, PropertyAttributes *attributes);
 
     static QV4::ReturnedValue method_toString(CallContext *ctx);
 

tests/auto/qml/qqmlvaluetypes/tst_qqmlvaluetypes.cpp

@@ -30,6 +30,7 @@
 #include <QQmlEngine>
 #include <QQmlComponent>
 #include <QDebug>
+#include <QJSValueIterator>
 #include <private/qquickvaluetypes_p.h>
 #include <private/qqmlglobal_p.h>
 #include "../../shared/util.h"
@@ -89,6 +90,7 @@ private slots:
     void customValueTypeInQml();
     void gadgetInheritance();
     void toStringConversion();
+    void enumerableProperties();
 
 private:
     QQmlEngine engine;
@@ -1649,6 +1651,25 @@ void tst_qqmlvaluetypes::toStringConversion()
     QCOMPARE(stringConversion.toString(), StringLessGadget_to_QString(g));
 }
 
+void tst_qqmlvaluetypes::enumerableProperties()
+{
+    QJSEngine engine;
+    DerivedGadget g;
+    QJSValue value = engine.toScriptValue(g);
+    QSet<QString> names;
+    QJSValueIterator it(value);
+    while (it.hasNext()) {
+        it.next();
+        const QString name = it.name();
+        QVERIFY(!names.contains(name));
+        names.insert(name);
+    }
+
+    QCOMPARE(names.count(), 2);
+    QVERIFY(names.contains(QStringLiteral("baseProperty")));
+    QVERIFY(names.contains(QStringLiteral("derivedProperty")));
+}
+
 
 QTEST_MAIN(tst_qqmlvaluetypes)