Fix thisObject when calling scope and context properties through lookups

Just like resolving the lookup initially, we need to set the base also
when hitting the cached lookup code path. The base is then used as this
object.

Fixes: QTBUG-76656
Change-Id: I6f6be05bc9875ddccc6e112e91176a0fa24a8fa1
Reviewed-by: Michael Brasser <michael.brasser@live.com>
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

src/qml/jsruntime/qv4qmlcontext.cpp

@@ -539,7 +539,6 @@ ReturnedValue QQmlContextWrapper::lookupIdObject(Lookup *l, ExecutionEngine *eng
 
 ReturnedValue QQmlContextWrapper::lookupScopeObjectProperty(Lookup *l, ExecutionEngine *engine, Value *base)
 {
-    Q_UNUSED(base)
     Scope scope(engine);
     Scoped<QmlContext> qmlContext(scope, engine->qmlContext());
     if (!qmlContext)
@@ -560,12 +559,15 @@ ReturnedValue QQmlContextWrapper::lookupScopeObjectProperty(Lookup *l, Execution
     };
 
     ScopedValue obj(scope, QV4::QObjectWrapper::wrap(engine, scopeObject));
+
+    if (base)
+        *base = obj;
+
     return QObjectWrapper::lookupGetterImpl(l, engine, obj, /*useOriginalProperty*/ true, revertLookup);
 }
 
 ReturnedValue QQmlContextWrapper::lookupContextObjectProperty(Lookup *l, ExecutionEngine *engine, Value *base)
 {
-    Q_UNUSED(base)
     Scope scope(engine);
     Scoped<QmlContext> qmlContext(scope, engine->qmlContext());
     if (!qmlContext)
@@ -590,6 +592,10 @@ ReturnedValue QQmlContextWrapper::lookupContextObjectProperty(Lookup *l, Executi
     };
 
     ScopedValue obj(scope, QV4::QObjectWrapper::wrap(engine, contextObject));
+
+    if (base)
+        *base = obj;
+
     return QObjectWrapper::lookupGetterImpl(l, engine, obj, /*useOriginalProperty*/ true, revertLookup);
 }
 

tests/auto/qml/qqmlecmascript/data/getThis.qml

@@ -0,0 +1,60 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL3$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPLv3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or later as published by the Free
+** Software Foundation and appearing in the file LICENSE.GPL included in
+** the packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 2.0 requirements will be
+** met: http://www.gnu.org/licenses/gpl-2.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQml 2.12
+
+QtObject {
+    id: root
+    property QtObject self;
+
+    property Timer timer: Timer {
+        running: true
+        interval: 1
+        onTriggered: {
+            root.assignThis();
+            root.self = null;
+            root.assignThis();
+        }
+    }
+
+    function getThis() {
+        return this;
+    }
+
+    function assignThis() {
+        self = getThis();
+    }
+}

tests/auto/qml/qqmlecmascript/tst_qqmlecmascript.cpp

@@ -370,6 +370,7 @@ private slots:
     void undefinedPropertiesInObjectWrapper();
     void hugeRegexpQuantifiers();
     void singletonTypeWrapperLookup();
+    void getThisObject();
 
 private:
 //    static void propertyVarWeakRefCallback(v8::Persistent<v8::Value> object, void* parameter);
@@ -9029,6 +9030,17 @@ void tst_qqmlecmascript::singletonTypeWrapperLookup()
     QCOMPARE(test->property("secondLookup").toInt(), singleton2->testVar);
 }
 
+void tst_qqmlecmascript::getThisObject()
+{
+    QQmlEngine engine;
+    QQmlComponent component(&engine, testFileUrl("getThis.qml"));
+    QVERIFY(component.isReady());
+    QScopedPointer<QObject> test(component.create());
+    QVERIFY(!test.isNull());
+
+    QTRY_COMPARE(qvariant_cast<QObject *>(test->property("self")), test.data());
+}
+
 QTEST_MAIN(tst_qqmlecmascript)
 
 #include "tst_qqmlecmascript.moc"