Fix lost reference for item delegates

After setting an item delegate for columns and rows
in classes that inherit from QAbstractItemView (like QTreeView)
the reference was not kept, causing a segfault.
This was solved by keeping the reference of the object.
A test is provided.

Task-number: PYSIDE-226
Task-number: PYSIDE-219
Change-Id: I43eeb6e85a37537311d838f5abb0ee1ab10ea713
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

3 files changed, 100 insertions, 0 deletions

diff --git a/sources/pyside2/PySide2/QtWidgets/typesystem_widgets_common.xml b/sources/pyside2/PySide2/QtWidgets/typesystem_widgets_common.xml
index 60bb24335..0555d9a53 100644
--- a/sources/pyside2/PySide2/QtWidgets/typesystem_widgets_common.xml
+++ b/sources/pyside2/PySide2/QtWidgets/typesystem_widgets_common.xml
@@ -435,6 +435,16 @@
         <reference-count action="set"/>
       </modify-argument>
     </modify-function>
+    <modify-function signature="setItemDelegateForColumn(int, QAbstractItemDelegate*)">
+      <modify-argument index="2">
+        <reference-count action="set"/>
+      </modify-argument>
+    </modify-function>
+    <modify-function signature="setItemDelegateForRow(int, QAbstractItemDelegate*)">
+      <modify-argument index="2">
+        <reference-count action="set"/>
+      </modify-argument>
+    </modify-function>
     <modify-function signature="viewOptions()const">
       <modify-argument index="return">
         <replace-default-expression with="QStyleOptionViewItem()" />
diff --git a/sources/pyside2/tests/QtWidgets/CMakeLists.txt b/sources/pyside2/tests/QtWidgets/CMakeLists.txt
index af3a476b1..4efd9d803 100644
--- a/sources/pyside2/tests/QtWidgets/CMakeLists.txt
+++ b/sources/pyside2/tests/QtWidgets/CMakeLists.txt
@@ -120,6 +120,7 @@ PYSIDE_TEST(qtabwidget_test.py)
 PYSIDE_TEST(qtabwidgetclear_test.py)
 PYSIDE_TEST(qtextedit_test.py)
 PYSIDE_TEST(qtextedit_signal_test.py)
+PYSIDE_TEST(qtreeview_test.py)
 PYSIDE_TEST(qtoolbar_test.py)
 PYSIDE_TEST(qtoolbox_test.py)
 PYSIDE_TEST(qvalidator_test.py)
diff --git a/sources/pyside2/tests/QtWidgets/qtreeview_test.py b/sources/pyside2/tests/QtWidgets/qtreeview_test.py
new file mode 100644
index 000000000..a731ddafa
--- /dev/null
+++ b/sources/pyside2/tests/QtWidgets/qtreeview_test.py
@@ -0,0 +1,89 @@
+#############################################################################
+##
+## Copyright (C) 2018 The Qt Company Ltd.
+## Contact: https://www.qt.io/licensing/
+##
+## This file is part of the test suite of PySide2.
+##
+## $QT_BEGIN_LICENSE:GPL-EXCEPT$
+## 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 https://www.qt.io/terms-conditions. For further
+## information use the contact form at https://www.qt.io/contact-us.
+##
+## GNU General Public License Usage
+## Alternatively, this file may be used under the terms of the GNU
+## General Public License version 3 as published by the Free Software
+## Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+## included in the packaging of this file. Please review the following
+## information to ensure the GNU General Public License requirements will
+## be met: https://www.gnu.org/licenses/gpl-3.0.html.
+##
+## $QT_END_LICENSE$
+##
+#############################################################################
+
+import unittest
+
+from PySide2.QtGui import QStandardItemModel
+from PySide2.QtWidgets import QWidget, QTreeView, QVBoxLayout, QStyledItemDelegate
+from helper import UsesQApplication
+
+class Widget(QWidget):
+    def __init__(self, parent=None):
+        QWidget.__init__(self, parent)
+        self.treeView = QTreeView(self)
+        layout = QVBoxLayout()
+        layout.addWidget(self.treeView)
+        self.setLayout(layout)
+        self.treeView.setModel(QStandardItemModel())
+
+        self.treeView.model().setHorizontalHeaderLabels(('3', '1', '5'))
+
+class QWidgetTest(UsesQApplication):
+
+    def testDelegates(self):
+        widget = Widget()
+        t = widget.treeView
+
+        # When calling setItemDelegateForColumn using a separate variable
+        # for the second argument (QAbstractItemDelegate), there was no problem
+        # on keeping the reference to this object, since the variable was kept
+        # alive (case A)
+        # Contrary, when instantiating this argument on the function call
+        # Using QStyledItemDelegate inside the call the reference of the
+        # object was lost, causing a segfault. (case B)
+
+        # Case A
+        d = QStyledItemDelegate()
+        # Using QStyledItemDelegate from a variable so we keep the reference alive
+        # and we encounter no segfault.
+        t.setItemDelegateForColumn(0, d)
+        # This raised the Segmentation Fault too, because manually destroying
+        # the object caused a missing refrence.
+        del d
+
+        # Getting the delegates
+        a = t.itemDelegateForColumn(0)
+        self.assertIsInstance(a, QStyledItemDelegate)
+
+        # Case B
+        t.setItemDelegateForColumn(1, QStyledItemDelegate())
+
+        # Getting the delegates
+        b = t.itemDelegateForColumn(1)
+        self.assertIsInstance(b, QStyledItemDelegate)
+
+        # Test for Rows
+        t.setItemDelegateForRow(0, QStyledItemDelegate())
+        self.assertIsInstance(t.itemDelegateForRow(0), QStyledItemDelegate)
+
+        # Test for general delegate
+        t.setItemDelegate(QStyledItemDelegate())
+        self.assertIsInstance(t.itemDelegate(), QStyledItemDelegate)
+
+if __name__ == '__main__':
+    unittest.main()