Enable conversion from QJSValues containing arrays to container types

We started to convert containers to QJSValues, so that we could use them
as JavaScript arrays. Unfortunately, this would then lead to a type missmatch
when those same values where to be stored in a property of the container
type. This commit fixes this by converting them back to the original
type.

Fixes: QTBUG-80916
Change-Id: I30a3b03e17c34b171d4a6881dfd7801c13e94d80
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

5 files changed, 63 insertions, 7 deletions

diff --git a/src/qml/jsruntime/qv4engine.cpp b/src/qml/jsruntime/qv4engine.cpp
index c81661033a..81f55673cd 100644
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -1508,12 +1508,35 @@ static QVariant toVariant(QV4::ExecutionEngine *e, const QV4::Value &value, int
             return QVariant::fromValue(QV4::JsonObject::toJsonArray(a));
         }
 
+        QVariant retn;
 #if QT_CONFIG(qml_sequence_object)
         bool succeeded = false;
-        QVariant retn = QV4::SequencePrototype::toVariant(value, typeHint, &succeeded);
+        retn = QV4::SequencePrototype::toVariant(value, typeHint, &succeeded);
         if (succeeded)
             return retn;
 #endif
+        retn = QVariant(typeHint, QMetaType::create(typeHint));
+        auto retnAsIterable = retn.value<QtMetaTypePrivate::QSequentialIterableImpl>();
+        if (retnAsIterable._iteratorCapabilities & QtMetaTypePrivate::ContainerIsAppendable) {
+            auto const length = a->getLength();
+            QV4::ScopedValue arrayValue(scope);
+            for (qint64 i = 0; i < length; ++i) {
+                arrayValue = a->get(i);
+                QVariant asVariant = toVariant(e, arrayValue, retnAsIterable._metaType_id, false, visitedObjects);
+                auto originalType = asVariant.userType();
+                bool couldConvert = asVariant.convert(retnAsIterable._metaType_id);
+                if (!couldConvert) {
+                    qWarning() << QLatin1String("Could not convert array value at position %1 from %2 to %3")
+                                                .arg(QString::number(i),
+                                                     QMetaType::typeName(originalType),
+                                                     QMetaType::typeName(retnAsIterable._metaType_id));
+                    // create default constructed value
+                    asVariant = QVariant(retnAsIterable._metaType_id, nullptr);
+                }
+                retnAsIterable.append(asVariant.constData());
+            }
+            return retn;
+        }
     }
 
     if (value.isUndefined())
diff --git a/tests/auto/qml/qqmlecmascript/data/sequenceConversion.write.error.qml b/tests/auto/qml/qqmlecmascript/data/sequenceConversion.write.error.qml
index 75beafd1ee..c2c8c1b52b 100644
--- a/tests/auto/qml/qqmlecmascript/data/sequenceConversion.write.error.qml
+++ b/tests/auto/qml/qqmlecmascript/data/sequenceConversion.write.error.qml
@@ -12,7 +12,7 @@ Item {
 
     function performTest() {
         // we have NOT registered QList<QPoint> as a type
-        var pointList = [ Qt.point(7,7), Qt.point(8,8), Qt.point(9,9) ];
+        var pointList = [ Qt.point(7,7), "hello world", Qt.point(8,8), Qt.point(9,9) ];
         msco.pointListProperty = pointList; // error.
     }
 }
diff --git a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
index 370ef5f065..26232ac1a3 100644
--- a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
+++ b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
@@ -5792,13 +5792,12 @@ void tst_qqmlecmascript::sequenceConversionWrite()
         MySequenceConversionObject *seq = object->findChild<MySequenceConversionObject*>("msco");
         QVERIFY(seq != nullptr);
 
-        // we haven't registered QList<QPoint> as a sequence type, so writing shouldn't work.
-        QString warningOne = qmlFile.toString() + QLatin1String(":16: Error: Cannot assign QJSValue to QList<QPoint>");
-        QTest::ignoreMessage(QtWarningMsg, warningOne.toLatin1().constData());
-
+        // Behavior change in 5.14: due to added auto-magical conversions, it is possible to assign to
+        // QList<QPoint>, even though it is not a registered sequence type
+        QTest::ignoreMessage(QtMsgType::QtWarningMsg, QRegularExpression("Could not convert array value at position 1 from QString to QPoint"));
         QMetaObject::invokeMethod(object, "performTest");
 
-        QList<QPoint> pointList; pointList << QPoint(1, 2) << QPoint(3, 4) << QPoint(5, 6); // original values, shouldn't have changed
+        QList<QPoint> pointList; pointList << QPoint(7, 7) << QPoint(0,0) << QPoint(8, 8) << QPoint(9, 9); // original values, shouldn't have changed
         QCOMPARE(seq->pointListProperty(), pointList);
 
         delete object;
diff --git a/tests/auto/qml/qqmllanguage/data/arrayToContainer.qml b/tests/auto/qml/qqmllanguage/data/arrayToContainer.qml
new file mode 100644
index 0000000000..ee400eb41f
--- /dev/null
+++ b/tests/auto/qml/qqmllanguage/data/arrayToContainer.qml
@@ -0,0 +1,7 @@
+import QtQml 2.14
+import qt.test 1.0
+
+TestItem {
+    property var vector
+    positions: vector
+}
diff --git a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
index fae74f1f25..4a8ce77f92 100644
--- a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
+++ b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
@@ -303,6 +303,8 @@ private slots:
 
     void typeWrapperToVariant();
 
+    void arrayToContainer();
+
 private:
     QQmlEngine engine;
     QStringList defaultImportPathList;
@@ -5238,6 +5240,31 @@ void tst_qqmllanguage::typeWrapperToVariant()
     QVERIFY(target);
 }
 
+class TestItem : public QObject
+{
+    Q_OBJECT
+    Q_PROPERTY( QVector<QPointF> positions MEMBER m_points  )
+
+public:
+    TestItem() = default;
+    QVector< QPointF > m_points;
+};
+
+
+Q_DECLARE_METATYPE(QVector<QPointF>);
+void tst_qqmllanguage::arrayToContainer()
+{
+    QQmlEngine engine;
+    qmlRegisterType<TestItem>("qt.test", 1, 0, "TestItem");
+    QVector<QPointF> points { QPointF (2.0, 3.0) };
+    engine.rootContext()->setContextProperty("test", QVariant::fromValue(points));
+    QQmlComponent component(&engine, testFileUrl("arrayToContainer.qml"));
+    VERIFY_ERRORS(0);
+    QScopedPointer<TestItem> root(qobject_cast<TestItem *>(component.createWithInitialProperties( {{"vector", QVariant::fromValue(points)}} )));
+    QVERIFY(root);
+    QCOMPARE(root->m_points.at(0), QPointF (2.0, 3.0) );
+}
+
 QTEST_MAIN(tst_qqmllanguage)
 
 #include "tst_qqmllanguage.moc"