QML: Un-specialcase QStringList and QVariantList conversion

Those are just regular sequences these days. They can be written back.
Drop some now-dead code and deduplicate the value type conversion code
in the process. We should try the (more common) value type conversion
before the sequence conversion, but after all the "simple" conversions.

[ChangeLog][QtQml][Important Behavior Changes] Converting a QVariantList
to a QJSValue via, for example QJSEngine::toScriptValue() does not
produce a JavaScript array anymore, but rather a better suited sequence
object that behaves almost like a JavaScript array. The only difference
is that its QJSValue::isArray() will return false now.

Fixes: QTBUG-113690
Change-Id: Ib176c34d59c45a6b5cff68d029c4b1b87d7aa192
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 13 insertions, 4 deletions

diff --git a/src/qml/jsruntime/qv4jscall_p.h b/src/qml/jsruntime/qv4jscall_p.h
index e824863b29..7bb38a5fe9 100644
--- a/src/qml/jsruntime/qv4jscall_p.h
+++ b/src/qml/jsruntime/qv4jscall_p.h
@@ -233,9 +233,17 @@ inline ReturnedValue coerceListType(
     ExecutionEngine *engine, const Value &value, const QQmlType &qmlType)
 {
     QMetaType type = qmlType.qListTypeId();
+    const auto metaSequence = [&]() {
+        // TODO: We should really add the metasequence to the same QQmlType that holds
+        //       all the other type information. Then we can get rid of the extra
+        //       QQmlMetaType::qmlListType() here.
+        return qmlType.isSequentialContainer()
+                ? qmlType.listMetaSequence()
+                : QQmlMetaType::qmlListType(type).listMetaSequence();
+    };
+
     if (const QV4::Sequence *sequence = value.as<QV4::Sequence>()) {
-        const QQmlTypePrivate *typePrivate = sequence->d()->typePrivate();
-        if (typePrivate->listId == type)
+        if (sequence->d()->listType() == type)
             return value.asReturnedValue();
     }
 
@@ -256,7 +264,7 @@ inline ReturnedValue coerceListType(
     if (!array) {
         return (listValueType.flags() & QMetaType::PointerToQObject)
                    ? QmlListWrapper::create(engine, listValueType)
-                   : SequencePrototype::fromData(engine, type, nullptr);
+                   : SequencePrototype::fromData(engine, type, metaSequence(), nullptr);
     }
 
     if (listValueType.flags() & QMetaType::PointerToQObject) {
@@ -273,7 +281,8 @@ inline ReturnedValue coerceListType(
         return newList->asReturnedValue();
     }
 
-    QV4::Scoped<Sequence> sequence(scope, SequencePrototype::fromData(engine, type, nullptr));
+    QV4::Scoped<Sequence> sequence(
+            scope, SequencePrototype::fromData(engine, type, metaSequence(), nullptr));
     const qsizetype length = array->getLength();
     for (qsizetype i = 0; i < length; ++i)
         sequence->containerPutIndexed(i, array->get(i));