Fix mapping of JS objects/arrays to C++

[ChangeLog][QtQml][Important Behavior Changes] When a JavaScript object/array
is passed to C++ through a QVariant, the engine no longer immediately converts
the object recursively into a QVariantMap or QVariantList but instead stores
a QJSValue in the QVariant. This prevents a loss of data when the JS object
contains non-primitive types such as function objects for example. Code that
expects the variant type to be exactly QVariant::Map or QVariant::List may
need to be adapted. Registered conversion functions however ensure that code
that merely calls toMap() or toList() continues to work.

Task-number: QTBUG-40431
Change-Id: I1dbc1d5f8e78ad28bb62db3681b9a0b34557e7f5
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

2 files changed, 2 insertions, 6 deletions

diff --git a/src/qml/jsruntime/qv4qobjectwrapper.cpp b/src/qml/jsruntime/qv4qobjectwrapper.cpp
index ff51ee6c6f..32379f7f1e 100644
--- a/src/qml/jsruntime/qv4qobjectwrapper.cpp
+++ b/src/qml/jsruntime/qv4qobjectwrapper.cpp
@@ -1665,17 +1665,13 @@ void CallArgument::fromValue(int callType, QV8Engine *engine, const QV4::ValueRe
         type = -1;
 
         QQmlEnginePrivate *ep = engine->engine() ? QQmlEnginePrivate::get(engine->engine()) : 0;
-        QVariant v = engine->toVariant(value, -1); // why -1 instead of callType?
+        QVariant v = engine->toVariant(value, callType);
 
         if (v.userType() == callType) {
             *qvariantPtr = v;
         } else if (v.canConvert(callType)) {
             *qvariantPtr = v;
             qvariantPtr->convert(callType);
-        } else if (QV4::SequencePrototype::isSequenceType(callType) && v.userType() == qMetaTypeId<QVariantList>()) {
-            // convert the JS array to a sequence of the correct type.
-            QVariant seqV = engine->toVariant(value, callType);
-            *qvariantPtr = seqV;
         } else {
             QQmlMetaObject mo = ep ? ep->rawMetaObjectForType(callType) : QQmlMetaObject();
             if (!mo.isNull()) {
diff --git a/src/qml/jsruntime/qv4variantobject.cpp b/src/qml/jsruntime/qv4variantobject.cpp
index 34657501e8..68b08fb3ca 100644
--- a/src/qml/jsruntime/qv4variantobject.cpp
+++ b/src/qml/jsruntime/qv4variantobject.cpp
@@ -59,7 +59,7 @@ VariantObject::Data::Data(ExecutionEngine *engine, const QVariant &value)
 QVariant VariantObject::toVariant(const QV4::ValueRef v)
 {
     if (v->asObject())
-        return v->engine()->v8Engine->variantFromJS(v);
+        return v->engine()->v8Engine->toVariant(v, /*typeHint*/ -1, /*createJSValueForObjects*/ false);
 
     if (v->isString())
         return QVariant(v->stringValue()->toQString());