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>

5 files changed, 69 insertions, 22 deletions

diff --git a/tests/auto/qml/qjsvalue/tst_qjsvalue.cpp b/tests/auto/qml/qjsvalue/tst_qjsvalue.cpp
index 837403d391..9c615cfc15 100644
--- a/tests/auto/qml/qjsvalue/tst_qjsvalue.cpp
+++ b/tests/auto/qml/qjsvalue/tst_qjsvalue.cpp
@@ -34,10 +34,6 @@
 #include "tst_qjsvalue.h"
 #include <QtWidgets/QPushButton>
 
-QT_BEGIN_NAMESPACE
-extern bool qt_script_isJITEnabled();
-QT_END_NAMESPACE
-
 tst_QJSValue::tst_QJSValue()
     : engine(0)
 {
@@ -45,8 +41,7 @@ tst_QJSValue::tst_QJSValue()
 
 tst_QJSValue::~tst_QJSValue()
 {
-    if (engine)
-        delete engine;
+    delete engine;
 }
 
 void tst_QJSValue::ctor_invalid()
@@ -308,6 +303,19 @@ void tst_QJSValue::ctor_copyAndAssign()
     QCOMPARE(v5.toNumber(), 1.0);
 }
 
+static QJSValue createUnboundValue(const QJSValue &value)
+{
+    QVariant variant = QVariant::fromValue(value);
+    QBuffer buffer;
+    buffer.open(QIODevice::ReadWrite);
+    QDataStream stream(&buffer);
+    variant.save(stream);
+    buffer.seek(0);
+    QVariant resultVariant;
+    resultVariant.load(stream);
+    return resultVariant.value<QJSValue>();
+}
+
 void tst_QJSValue::toString()
 {
     QJSEngine eng;
@@ -406,6 +414,28 @@ void tst_QJSValue::toString()
     variant = eng.toScriptValue(QUrl());
     QVERIFY(variant.isVariant());
     QVERIFY(variant.toString().isEmpty());
+
+    {
+        QJSValue o = eng.newObject();
+        o.setProperty(QStringLiteral("test"), 42);
+        QCOMPARE(o.toString(), QStringLiteral("[object Object]"));
+
+        o = createUnboundValue(o);
+        QVERIFY(!o.engine());
+        QCOMPARE(o.toString(), QStringLiteral("[object Object]"));
+    }
+
+    {
+        QJSValue o = eng.newArray();
+        o.setProperty(0, 1);
+        o.setProperty(1, 2);
+        o.setProperty(2, 3);
+        QCOMPARE(o.toString(), QStringLiteral("1,2,3"));
+
+        o = createUnboundValue(o);
+        QVERIFY(!o.engine());
+        QCOMPARE(o.toString(), QStringLiteral("1,2,3"));
+    }
 }
 
 void tst_QJSValue::toNumber()
@@ -419,35 +449,43 @@ void tst_QJSValue::toNumber()
     QJSValue null = eng.evaluate("null");
     QCOMPARE(null.toNumber(), 0.0);
     QCOMPARE(qjsvalue_cast<qreal>(null), 0.0);
+    QCOMPARE(createUnboundValue(null).toNumber(), 0.0);
 
     {
         QJSValue falskt = eng.toScriptValue(false);
         QCOMPARE(falskt.toNumber(), 0.0);
+        QCOMPARE(createUnboundValue(falskt).toNumber(), 0.0);
         QCOMPARE(qjsvalue_cast<qreal>(falskt), 0.0);
 
         QJSValue sant = eng.toScriptValue(true);
         QCOMPARE(sant.toNumber(), 1.0);
+        QCOMPARE(createUnboundValue(sant).toNumber(), 1.0);
         QCOMPARE(qjsvalue_cast<qreal>(sant), 1.0);
 
         QJSValue number = eng.toScriptValue(123.0);
         QCOMPARE(number.toNumber(), 123.0);
         QCOMPARE(qjsvalue_cast<qreal>(number), 123.0);
+        QCOMPARE(createUnboundValue(number).toNumber(), 123.0);
 
         QJSValue str = eng.toScriptValue(QString("ciao"));
         QCOMPARE(qIsNaN(str.toNumber()), true);
         QCOMPARE(qIsNaN(qjsvalue_cast<qreal>(str)), true);
+        QCOMPARE(qIsNaN(createUnboundValue(str).toNumber()), true);
 
         QJSValue str2 = eng.toScriptValue(QString("123"));
         QCOMPARE(str2.toNumber(), 123.0);
         QCOMPARE(qjsvalue_cast<qreal>(str2), 123.0);
+        QCOMPARE(createUnboundValue(str2).toNumber(), 123.0);
     }
 
     QJSValue object = eng.newObject();
     QCOMPARE(qIsNaN(object.toNumber()), true);
+    QCOMPARE(qIsNaN(createUnboundValue(object).toNumber()), true);
     QCOMPARE(qIsNaN(qjsvalue_cast<qreal>(object)), true);
 
     QJSValue inv = QJSValue();
     QVERIFY(qIsNaN(inv.toNumber()));
+    QCOMPARE(qIsNaN(createUnboundValue(inv).toNumber()), true);
     QVERIFY(qIsNaN(qjsvalue_cast<qreal>(inv)));
 
     // V2 constructors
diff --git a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
index c246647325..196f6b96f9 100644
--- a/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
+++ b/tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp
@@ -746,13 +746,13 @@ void tst_qqmlecmascript::arrayExpressions()
 
     MyExpression expr(&context, "[a, b, c, 10]");
     QVariant result = expr.evaluate();
-    QCOMPARE(result.userType(), qMetaTypeId<QVariantList>());
-    QVariantList list = qvariant_cast<QVariantList>(result);
-    QCOMPARE(list.count(), 4);
-    QCOMPARE(list.at(0).value<QObject*>(), &obj1);
-    QCOMPARE(list.at(1).value<QObject*>(), &obj2);
-    QCOMPARE(list.at(2).value<QObject*>(), &obj3);
-    QCOMPARE(list.at(3).value<int>(), 10);
+    QCOMPARE(result.userType(), qMetaTypeId<QJSValue>());
+    QJSValue list = qvariant_cast<QJSValue>(result);
+    QCOMPARE(list.property("length").toInt(), 4);
+    QCOMPARE(list.property(0).toQObject(), &obj1);
+    QCOMPARE(list.property(1).toQObject(), &obj2);
+    QCOMPARE(list.property(2).toQObject(), &obj3);
+    QCOMPARE(list.property(3).toInt(), 10);
 }
 
 // Tests that modifying a context property will reevaluate expressions
@@ -4811,7 +4811,7 @@ void tst_qqmlecmascript::propertyVarCpp()
     QCOMPARE(object->property("varProperty2"), QVariant(QLatin1String("randomString")));
     QCOMPARE(object->property("varProperty2").userType(), (int)QVariant::String);
     // now enforce behaviour when accessing JavaScript objects from cpp.
-    QCOMPARE(object->property("jsobject").userType(), (int)QVariant::Map);
+    QCOMPARE(object->property("jsobject").userType(), qMetaTypeId<QJSValue>());
     delete object;
 }
 
@@ -5166,7 +5166,7 @@ void tst_qqmlecmascript::objectConversion()
     QVERIFY(object != 0);
     QVariant retn;
     QMetaObject::invokeMethod(object, "circularObject", Q_RETURN_ARG(QVariant, retn));
-    QCOMPARE(retn.value<QVariantMap>().value("test"), QVariant(100));
+    QCOMPARE(retn.value<QJSValue>().property("test").toInt(), int(100));
 
     delete object;
 }
@@ -5434,7 +5434,7 @@ void tst_qqmlecmascript::sequenceConversionWrite()
         QVERIFY(seq != 0);
 
         // we haven't registered QList<QPoint> as a sequence type, so writing shouldn't work.
-        QString warningOne = qmlFile.toString() + QLatin1String(":16: Error: Cannot assign QVariantList to an unregistered type");
+        QString warningOne = qmlFile.toString() + QLatin1String(":16: Error: Cannot assign QJSValue to an unregistered type");
         QTest::ignoreMessage(QtWarningMsg, warningOne.toLatin1().constData());
 
         QMetaObject::invokeMethod(object, "performTest");
diff --git a/tests/auto/qml/qqmllocale/tst_qqmllocale.cpp b/tests/auto/qml/qqmllocale/tst_qqmllocale.cpp
index 320333f889..4ee75f8df5 100644
--- a/tests/auto/qml/qqmllocale/tst_qqmllocale.cpp
+++ b/tests/auto/qml/qqmllocale/tst_qqmllocale.cpp
@@ -486,7 +486,7 @@ void tst_qqmllocale::weekDays()
         Q_ARG(QVariant, QVariant(locale)));
 
     QVariant val = obj->property("weekDays");
-    QVERIFY(val.type() == QVariant::List);
+    QVERIFY(val.userType() == qMetaTypeId<QJSValue>());
 
     QList<QVariant> qmlDays = val.toList();
     QList<Qt::DayOfWeek> days = QLocale(locale).weekdays();
@@ -528,7 +528,7 @@ void tst_qqmllocale::uiLanguages()
         Q_ARG(QVariant, QVariant(locale)));
 
     QVariant val = obj->property("uiLanguages");
-    QVERIFY(val.type() == QVariant::List);
+    QVERIFY(val.userType() == qMetaTypeId<QJSValue>());
 
     QList<QVariant> qmlLangs = val.toList();
     QStringList langs = QLocale(locale).uiLanguages();
diff --git a/tests/auto/qml/qqmlmetaobject/tst_qqmlmetaobject.cpp b/tests/auto/qml/qqmlmetaobject/tst_qqmlmetaobject.cpp
index 510a76cc06..b6e7a43c46 100644
--- a/tests/auto/qml/qqmlmetaobject/tst_qqmlmetaobject.cpp
+++ b/tests/auto/qml/qqmlmetaobject/tst_qqmlmetaobject.cpp
@@ -249,16 +249,22 @@ void tst_QQmlMetaObject::property()
     QSignalSpy changedSpy(object, SIGNAL(testChanged()));
     QObject::connect(object, SIGNAL(testChanged()), object, SLOT(deleteLater()));
 
+    QVariant value = prop.read(object);
+    if (value.userType() == qMetaTypeId<QJSValue>())
+        value = value.value<QJSValue>().toVariant();
     if (expectedValue.isValid())
-        QCOMPARE(prop.read(object), expectedValue);
+        QCOMPARE(value, expectedValue);
     else
-        QVERIFY(prop.read(object).isValid());
+        QVERIFY(value.isValid());
     QCOMPARE(changedSpy.count(), 0);
 
     if (isWritable) {
         QVERIFY(prop.write(object, newValue));
         QCOMPARE(changedSpy.count(), 1);
-        QCOMPARE(prop.read(object), newValue);
+        QVariant value = prop.read(object);
+        if (value.userType() == qMetaTypeId<QJSValue>())
+            value = value.value<QJSValue>().toVariant();
+        QCOMPARE(value, newValue);
     } else {
         QVERIFY(!prop.write(object, prop.read(object)));
         QCOMPARE(changedSpy.count(), 0);
diff --git a/tests/auto/qml/qquickworkerscript/tst_qquickworkerscript.cpp b/tests/auto/qml/qquickworkerscript/tst_qquickworkerscript.cpp
index 66ddb392f9..801707f2ec 100644
--- a/tests/auto/qml/qquickworkerscript/tst_qquickworkerscript.cpp
+++ b/tests/auto/qml/qquickworkerscript/tst_qquickworkerscript.cpp
@@ -115,7 +115,10 @@ void tst_QQuickWorkerScript::messaging()
     waitForEchoMessage(worker);
 
     const QMetaObject *mo = worker->metaObject();
-    QCOMPARE(mo->property(mo->indexOfProperty("response")).read(worker).value<QVariant>(), value);
+    QVariant response = mo->property(mo->indexOfProperty("response")).read(worker).value<QVariant>();
+    if (response.userType() == qMetaTypeId<QJSValue>())
+        response = response.value<QJSValue>().toVariant();
+    QCOMPARE(response, value);
 
     qApp->processEvents();
     delete worker;