Release dialogs when using QDialog.exec()

In the typical pattern ported from C++

dialog = QDialog(mainWin)
dialog.exec()

one would expected the dialog to be deleted. However,
due to the constructor heuristics creating a parent-child
relationship, the dialog leaks. Add a modification
to remove the relationship in case exec() is called.

Change-Id: Ibc6f8c150cbd80a4085af4a5b713ee7c2c62abf3
Reviewed-by: Shyamnath Premnadh <Shyamnath.Premnadh@qt.io>

4 files changed, 64 insertions, 1 deletions

diff --git a/sources/pyside6/PySide6/QtWidgets/typesystem_widgets_common.xml b/sources/pyside6/PySide6/QtWidgets/typesystem_widgets_common.xml
index 6b4ce7bbe..0669c18f6 100644
--- a/sources/pyside6/PySide6/QtWidgets/typesystem_widgets_common.xml
+++ b/sources/pyside6/PySide6/QtWidgets/typesystem_widgets_common.xml
@@ -491,7 +491,9 @@
   <object-type name="QDateEdit"/>
   <object-type name="QDialog">
     <enum-type name="DialogCode" python-type="IntEnum"/>
-    <modify-function signature="exec()" allow-thread="yes"/>
+    <modify-function signature="exec()" allow-thread="yes">
+        <inject-code file="../glue/qtwidgets.cpp" snippet="qdialog-exec-remove-parent-relation"/>
+    </modify-function>
     <add-function signature="exec_()" return-type="int">
         <inject-code file="../glue/qtwidgets.cpp" snippet="qapplication-exec"/>
     </add-function>
diff --git a/sources/pyside6/PySide6/glue/qtwidgets.cpp b/sources/pyside6/PySide6/glue/qtwidgets.cpp
index 18cce00bf..1b3e94016 100644
--- a/sources/pyside6/PySide6/glue/qtwidgets.cpp
+++ b/sources/pyside6/PySide6/glue/qtwidgets.cpp
@@ -803,6 +803,14 @@ const QByteArray signature = QByteArrayLiteral("2") + method.methodSignature();
 %END_ALLOW_THREADS
 // @snippet qwizardpage-registerfield
 
+// The constructor heuristics generate setting a parent-child relationship
+// when creating a QDialog with parent. This causes the dialog to leak
+// when it synchronous exec() is used instead of asynchronous show().
+// In that case, remove the parent-child relationship.
+// @snippet qdialog-exec-remove-parent-relation
+Shiboken::Object::removeParent(reinterpret_cast<SbkObject *>(%PYSELF));
+// @snippet qdialog-exec-remove-parent-relation
+
 /*********************************************************************
  * CONVERSIONS
  ********************************************************************/
diff --git a/sources/pyside6/tests/QtWidgets/CMakeLists.txt b/sources/pyside6/tests/QtWidgets/CMakeLists.txt
index 54e0d6c3a..01b7d08ea 100644
--- a/sources/pyside6/tests/QtWidgets/CMakeLists.txt
+++ b/sources/pyside6/tests/QtWidgets/CMakeLists.txt
@@ -84,6 +84,7 @@ PYSIDE_TEST(qapp_issue_585.py)
 PYSIDE_TEST(qapp_test.py)
 PYSIDE_TEST(qapplication_test.py)
 PYSIDE_TEST(qapplication_exit_segfault_test.py)
+PYSIDE_TEST(qdialog_test.py)
 PYSIDE_TEST(qdynamic_signal.py)
 # TODO: This passes, but requires manual button clicking (at least on mac)
 #PYSIDE_TEST(qfontdialog_test.py)
diff --git a/sources/pyside6/tests/QtWidgets/qdialog_test.py b/sources/pyside6/tests/QtWidgets/qdialog_test.py
new file mode 100644
index 000000000..cb85ce7e2
--- /dev/null
+++ b/sources/pyside6/tests/QtWidgets/qdialog_test.py
@@ -0,0 +1,52 @@
+# Copyright (C) 2022 The Qt Company Ltd.
+# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+import os
+import sys
+import unittest
+import weakref
+
+from pathlib import Path
+sys.path.append(os.fspath(Path(__file__).resolve().parents[1]))
+from init_paths import init_test_paths
+init_test_paths(False)
+
+from PySide6.QtCore import Slot, QTimer
+from PySide6.QtWidgets import QDialog, QMainWindow
+from helper.timedqapplication import TimedQApplication
+
+
+class Window(QMainWindow):
+    def __init__(self):
+        super().__init__()
+        self.setWindowTitle("Main")
+        self.dialog = None
+
+    @Slot()
+    def execDialog(self):
+        dialog = QDialog(self)
+        self.dialog = weakref.ref(dialog)
+        dialog.setWindowTitle("Dialog")
+        dialog.setMinimumWidth(200)
+        QTimer.singleShot(500, dialog.reject)
+        dialog.exec()
+        self.close()
+
+
+class DialogExecTest(TimedQApplication):
+    """Test whether the parent-child relationship (dialog/main window) is removed when
+       using QDialog.exec() (instead show()), preventing the dialog from leaking."""
+
+    def setUp(self):
+        super().setUp(10000)
+        self._window = Window()
+
+    def testExec(self):
+        self._window.show()
+        QTimer.singleShot(500, self._window.execDialog)
+        self.app.exec()
+        self.assertTrue(self._window.dialog() is None)
+
+
+if __name__ == '__main__':
+    unittest.main()