Fix crash when Layout.fillWidth is put into QtObject {}

Change-Id: I89e86cf0fc3f6421e1dadd41771dfc689dcdeb8a
Reviewed-by: Jan Arve Sæther <jan-arve.saether@digia.com>

src/layouts/qquicklayout.cpp

@@ -401,16 +401,19 @@ void QQuickLayoutAttached::invalidateItem()
 
 QQuickLayout *QQuickLayoutAttached::parentLayout() const
 {
-    QQuickItem *parentItem = item()->parentItem();
-    if (qobject_cast<QQuickLayout *>(parentItem))
-        return static_cast<QQuickLayout *>(parentItem);
+    QQuickItem *parentItem = item();
+    if (parentItem) {
+        parentItem = parentItem->parentItem();
+        return qobject_cast<QQuickLayout *>(parentItem);
+    } else {
+        qWarning("Layout must be attached to Item elements");
+    }
     return 0;
 }
 
 QQuickItem *QQuickLayoutAttached::item() const
 {
-    Q_ASSERT(qobject_cast<QQuickItem*>(parent()));
-    return static_cast<QQuickItem*>(parent());
+    return qobject_cast<QQuickItem *>(parent());
 }
 
 

tests/auto/controls/data/tst_layout.qml

+/****************************************************************************
+**
+** Copyright (C) 2013 Tasuku Suzuki <stasuku@gmail.com>
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt Quick Controls module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** You may use this file under the terms of the BSD license as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
+**     of its contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQuick 2.1
+import QtTest 1.0
+
+TestCase {
+    id: testCase
+    name: "Tests_Layout"
+    when:windowShown
+    width:400
+    height:400
+
+    function test_invalidParent() {
+        var object = Qt.createQmlObject('import QtQuick 2.1; import QtQuick.Layouts 1.0; QtObject { Layout.fillWidth: true }', testCase, '');
+        object.destroy()
+    }
+}
+