QQuickLayout: ensure that all change listeners are removed

The first fix for QTBUG-51927 (59c6c0e0) went to 5.6.2, where only the
SiblingOrder ChangeType was listened to by QQuickLayout. It was then
cherry-picked to 5.7 (5149aa68), where SiblingOrder was still the only
ChangeType in use.

3b4f00ec then optimized QQuickLayout by swapping connections for item
change listeners, but didn't check for usages of change types elsewhere
in the file.

This patch moves the change types into a variable that ensures there
is one place for future changes. 5.6 is not affected.

Task-number: QTBUG-51927
Change-Id: Ifd6e0545ce543ab79d6415e007b35c457cacc83a
Reviewed-by: Robin Burchell <robin.burchell@crimson.no>

3 files changed, 111 insertions, 0 deletions

diff --git a/tests/auto/quick/qquicklayouts/data/rowlayout/Container2.qml b/tests/auto/quick/qquicklayouts/data/rowlayout/Container2.qml
new file mode 100644
index 0000000000..248652e82b
--- /dev/null
+++ b/tests/auto/quick/qquicklayouts/data/rowlayout/Container2.qml
@@ -0,0 +1,55 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** 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 The Qt Company Ltd 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 2.9
+import QtQuick.Layouts 1.3
+
+Item {
+    objectName: "qtbug51927-container"
+    visible: true
+
+    default property alias _contents: customContent.data
+
+    ColumnLayout {
+        id: customContent
+        objectName: "qtbug51927-columnLayout"
+        anchors.fill: parent
+    }
+}
diff --git a/tests/auto/quick/qquicklayouts/data/rowlayout/ContainerUser2.qml b/tests/auto/quick/qquicklayouts/data/rowlayout/ContainerUser2.qml
new file mode 100644
index 0000000000..9def782d4a
--- /dev/null
+++ b/tests/auto/quick/qquicklayouts/data/rowlayout/ContainerUser2.qml
@@ -0,0 +1,46 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** 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 The Qt Company Ltd 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 2.6
+
+Container2 {
+    visible: true
+    Item {}
+}
diff --git a/tests/auto/quick/qquicklayouts/data/tst_rowlayout.qml b/tests/auto/quick/qquicklayouts/data/tst_rowlayout.qml
index 97860458fe..4346c5283e 100644
--- a/tests/auto/quick/qquicklayouts/data/tst_rowlayout.qml
+++ b/tests/auto/quick/qquicklayouts/data/tst_rowlayout.qml
@@ -959,5 +959,15 @@ Item {
             // Shouldn't crash.
             containerUser.destroy();
         }
+
+        function test_defaultPropertyAliasCrashAgain() {
+            var containerUserComponent = Qt.createComponent("rowlayout/ContainerUser2.qml");
+            compare(containerUserComponent.status, Component.Ready);
+
+            var containerUser = createTemporaryObject(containerUserComponent, testCase);
+            verify(containerUser);
+
+            // Shouldn't crash upon destroying containerUser.
+        }
     }
 }