Support the qApp macro correctly, final version incl. debug

For short the new features:
- there is a qApp in QtCore, QtGui and QtWidgets for compatibility,
  and also in __builtins__ for a true macro-like experience.
- if you delete any qApp variable, the Q*Application is reset and you can
  start over.

Long description:

There is a qApp macro in Qt5 which is equivalent to Q*Application.instance() .

Python does not have macros. Both PyQt5 and PySide2 have an
according structure in QtWidgets. In the case of PySide2, the qApp
variable is first initialized to None and later to QApplication().

This does not reflect the original sense of the qApp macro, because
 - it only handles QApplication,
 - it does not handle destruction.

This "macro" should live in QtCore, but both PyQt5 and PySide2 decided
to put this in QtWidgets. As a compromize, I propose to put qApp into
all three modules, and into __builtins__ as well, so wherever you
create an application, you find this "macro" in place.

While changing the code, I stumbled over the template
set_qapp_parent_for_orphan. I tried to make sense out of it and finally
removed it. There were no side effects but bug PYSIDE-85 is gone, now.

With some extra effort, I created a singleton qApp that changes itself.
This way, a true macro was simulated. Note that this was not possible
with a garbage collected variable, and I had to make shiboken aware of this.

As the final optimization, I turned qApp also into a fuse variable:
Delete any qApp variable and Q*Application will finish when there is
no extra reference.

Task-number: PYSIDE-85
Task-number: PYSIDE-571
Change-Id: I7a56b19858f63349c98b95778759a6a6de856938
Reviewed-by: Christian Tismer <tismer@stackless.com>

8 files changed, 34 insertions, 196 deletions

diff --git a/sources/pyside2/PySide2/QtCore/glue/qcoreapplication_init.cpp b/sources/pyside2/PySide2/QtCore/glue/qcoreapplication_init.cpp
index fec8cf416..b2dfae38f 100644
--- a/sources/pyside2/PySide2/QtCore/glue/qcoreapplication_init.cpp
+++ b/sources/pyside2/PySide2/QtCore/glue/qcoreapplication_init.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2017 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of PySide2.
@@ -37,22 +37,14 @@
 **
 ****************************************************************************/
 
-// Global variables used to store argc and argv values
-static int QCoreApplicationArgCount;
-static char** QCoreApplicationArgValues;
-
-void QCoreApplication_constructor(PyObject* self, PyObject* argv, QCoreApplicationWrapper** cptr)
+static void QCoreApplicationConstructor(PyObject *self, PyObject *pyargv, QCoreApplicationWrapper **cptr)
 {
-    if (QCoreApplication::instance()) {
-        PyErr_SetString(PyExc_RuntimeError, "A QCoreApplication instance already exists.");
-        return;
-    }
-
-    PyObject *stringlist = PyTuple_GET_ITEM(argv, 0);
-    if (Shiboken::listToArgcArgv(stringlist, &QCoreApplicationArgCount, &QCoreApplicationArgValues, "PySideApp")) {
-        *cptr = new QCoreApplicationWrapper(QCoreApplicationArgCount, QCoreApplicationArgValues);
+    static int argc;
+    static char **argv;
+    PyObject *stringlist = PyTuple_GET_ITEM(pyargv, 0);
+    if (Shiboken::listToArgcArgv(stringlist, &argc, &argv, "PySideApp")) {
+        *cptr = new QCoreApplicationWrapper(argc, argv);
         Shiboken::Object::releaseOwnership(reinterpret_cast<SbkObject*>(self));
         PySide::registerCleanupFunction(&PySide::destroyQCoreApplication);
-        Py_INCREF(self);
     }
 }
diff --git a/sources/pyside2/PySide2/QtCore/typesystem_core_common.xml b/sources/pyside2/PySide2/QtCore/typesystem_core_common.xml
index 03991af38..41a20a617 100644
--- a/sources/pyside2/PySide2/QtCore/typesystem_core_common.xml
+++ b/sources/pyside2/PySide2/QtCore/typesystem_core_common.xml
@@ -3215,7 +3215,7 @@
     </inject-documentation>
     <add-function signature="QCoreApplication(QStringList)">
         <inject-code>
-            QCoreApplication_constructor(%PYSELF, args, &amp;%0);
+            QCoreApplicationConstructor(%PYSELF, args, &amp;%0);
         </inject-code>
     </add-function>
     <!-- blocking functions -->
@@ -3226,23 +3226,24 @@
     <modify-function signature="sendPostedEvents(QObject*, int)" allow-thread="yes"/>
     <modify-function signature="instance()">
       <inject-code class="target">
-        QCoreApplication* app = QCoreApplication::instance();
-        PyObject* pyApp = Py_None;
+        QCoreApplication *app = QCoreApplication::instance();
+        PyObject *pyApp = Py_None;
         if (app) {
-            pyApp = reinterpret_cast&lt;PyObject*&gt;(Shiboken::BindingManager::instance().retrieveWrapper(app));
+            pyApp = reinterpret_cast&lt;PyObject*&gt;(
+                Shiboken::BindingManager::instance().retrieveWrapper(app));
             if (!pyApp)
-                pyApp = %CONVERTTOPYTHON[QCoreApplication*](app); // this will keep app live after python exit (extra ref)
+                pyApp = %CONVERTTOPYTHON[QCoreApplication*](app);
+                // this will keep app live after python exit (extra ref)
         }
+        // PYSIDE-571: make sure that we return the singleton "None"
+        if (pyApp == Py_None)
+            Py_DECREF(MakeSingletonQAppWrapper(0)); // here qApp and instance() diverge
         %PYARG_0 = pyApp;
         Py_XINCREF(%PYARG_0);
       </inject-code>
     </modify-function>
 
     <modify-function signature="exec()" rename="exec_" allow-thread="yes"/>
-    <!-- ### Obsolete
-    <modify-function signature="argc()" remove="all"/>
-    <modify-function signature="argv()" remove="all"/>
-    -->
     <modify-function signature="notify(QObject*,QEvent*)" allow-thread="yes">
       <modify-argument index="2" invalidate-after-use="yes"/>
     </modify-function>
diff --git a/sources/pyside2/PySide2/QtGui/glue/qguiapplication_init.cpp b/sources/pyside2/PySide2/QtGui/glue/qguiapplication_init.cpp
index 014e409b5..38a4c1ccb 100644
--- a/sources/pyside2/PySide2/QtGui/glue/qguiapplication_init.cpp
+++ b/sources/pyside2/PySide2/QtGui/glue/qguiapplication_init.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2017 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of PySide2.
@@ -37,34 +37,14 @@
 **
 ****************************************************************************/
 
-// Borrowed reference to QtGui module
-extern PyObject* moduleQtGui;
-
-static int QGuiApplicationArgCount;
-static char** QGuiApplicationArgValues;
-
-bool QGuiApplicationConstructorStart(PyObject* argv)
-{
-    if (QGuiApplication::instance()) {
-        PyErr_SetString(PyExc_RuntimeError, "A QGuiApplication instance already exists.");
-        return false;
-    }
-
-    return Shiboken::listToArgcArgv(argv, &QGuiApplicationArgCount, &QGuiApplicationArgValues, "PySideApp");
-}
-
-void QGuiApplicationConstructorEnd(PyObject* self)
-{
-    PySide::registerCleanupFunction(&PySide::destroyQCoreApplication);
-    Py_INCREF(self);
-}
-
-static void QGuiApplicationConstructor(PyObject* self, PyObject* argv, QGuiApplicationWrapper** cptr)
+static void QGuiApplicationConstructor(PyObject *self, PyObject *pyargv, QGuiApplicationWrapper **cptr)
 {
-    PyObject *stringlist = PyTuple_GET_ITEM(argv, 0);
-    if (QGuiApplicationConstructorStart(stringlist)) {
-        *cptr = new QGuiApplicationWrapper(QGuiApplicationArgCount, QGuiApplicationArgValues, 0);
+    static int argc;
+    static char **argv;
+    PyObject *stringlist = PyTuple_GET_ITEM(pyargv, 0);
+    if (Shiboken::listToArgcArgv(stringlist, &argc, &argv, "PySideApp")) {
+        *cptr = new QGuiApplicationWrapper(argc, argv, 0);
         Shiboken::Object::releaseOwnership(reinterpret_cast<SbkObject*>(self));
-        QGuiApplicationConstructorEnd(self);
+        PySide::registerCleanupFunction(&PySide::destroyQCoreApplication);
     }
 }
diff --git a/sources/pyside2/PySide2/QtGui/typesystem_gui_common.xml b/sources/pyside2/PySide2/QtGui/typesystem_gui_common.xml
index 0dad0b455..55bc438be 100644
--- a/sources/pyside2/PySide2/QtGui/typesystem_gui_common.xml
+++ b/sources/pyside2/PySide2/QtGui/typesystem_gui_common.xml
@@ -3220,10 +3220,7 @@
   <!-- Qt5: not sure if this needs support, skipped for now -->
   <rejection class="QWindow" function-name="nativeEvent"/>"
 
-  <!-- Qt5: here the new QGuiApplication and related things -->
   <object-type name="QGuiApplication">
-    <!-- Qt5: gone <enum-type name="ColorSpec"/> -->
-    <!-- Qt5: gone <enum-type name="Type"/> -->
     <extra-includes>
       <include file-name="QBasicTimer" location="global"/>
       <include file-name="QFont" location="global"/>
diff --git a/sources/pyside2/PySide2/QtWidgets/glue/qapplication_init.cpp b/sources/pyside2/PySide2/QtWidgets/glue/qapplication_init.cpp
index f1f1f84a6..1419f5755 100644
--- a/sources/pyside2/PySide2/QtWidgets/glue/qapplication_init.cpp
+++ b/sources/pyside2/PySide2/QtWidgets/glue/qapplication_init.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2017 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of PySide2.
@@ -37,44 +37,14 @@
 **
 ****************************************************************************/
 
-// Borrowed reference to QtWidgets module
-extern PyObject* moduleQtWidgets;
-
-static int QApplicationArgCount;
-static char** QApplicationArgValues;
-static const char QAPP_MACRO[] = "qApp";
-
-bool QApplicationConstructorStart(PyObject* argv)
-{
-    if (QApplication::instance()) {
-        PyErr_SetString(PyExc_RuntimeError, "A QApplication instance already exists.");
-        return false;
-    }
-
-    return Shiboken::listToArgcArgv(argv, &QApplicationArgCount, &QApplicationArgValues, "PySideApp");
-}
-
-void QApplicationConstructorEnd(PyObject* self)
-{
-    // Verify if qApp is in main module
-    PyObject* globalsDict = PyEval_GetGlobals();
-    if (globalsDict) {
-        PyObject* qAppObj = PyDict_GetItemString(globalsDict, QAPP_MACRO);
-        if (qAppObj)
-            PyDict_SetItemString(globalsDict, QAPP_MACRO, self);
-    }
-
-    PyObject_SetAttrString(moduleQtWidgets, QAPP_MACRO, self);
-    PySide::registerCleanupFunction(&PySide::destroyQCoreApplication);
-    Py_INCREF(self);
-}
-
-static void QApplicationConstructor(PyObject* self, PyObject* argv, QApplicationWrapper** cptr)
+static void QApplicationConstructor(PyObject *self, PyObject *pyargv, QApplicationWrapper **cptr)
 {
-    PyObject *stringlist = PyTuple_GET_ITEM(argv, 0);
-    if (QApplicationConstructorStart(stringlist)) {
-        *cptr = new QApplicationWrapper(QApplicationArgCount, QApplicationArgValues, 0);
+    static int argc;
+    static char **argv;
+    PyObject *stringlist = PyTuple_GET_ITEM(pyargv, 0);
+    if (Shiboken::listToArgcArgv(stringlist, &argc, &argv, "PySideApp")) {
+        *cptr = new QApplicationWrapper(argc, argv, 0);
         Shiboken::Object::releaseOwnership(reinterpret_cast<SbkObject*>(self));
-        QApplicationConstructorEnd(self);
+        PySide::registerCleanupFunction(&PySide::destroyQCoreApplication);
     }
 }
diff --git a/sources/pyside2/PySide2/QtWidgets/glue/qtwidgets_qapp.cpp b/sources/pyside2/PySide2/QtWidgets/glue/qtwidgets_qapp.cpp
deleted file mode 100644
index e041c7680..000000000
--- a/sources/pyside2/PySide2/QtWidgets/glue/qtwidgets_qapp.cpp
+++ /dev/null
@@ -1,49 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2016 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of PySide2.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** 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 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.LGPL3 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-3.0.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 (at your option) the GNU General
-** Public license version 3 or any later version approved by the KDE Free
-** Qt Foundation. The licenses are as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
-** 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-2.0.html and
-** https://www.gnu.org/licenses/gpl-3.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-// Init qApp macro to None.
-if (qApp) {
-    PyObject* pyApp = %CONVERTTOPYTHON[QApplication*](qApp);
-    Py_INCREF(pyApp);
-    PyModule_AddObject(module, "qApp", pyApp);
-} else {
-    Py_INCREF(Py_None);
-    PyModule_AddObject(module, "qApp", Py_None);
-}
-moduleQtWidgets = module;
diff --git a/sources/pyside2/PySide2/QtWidgets/typesystem_widgets_common.xml b/sources/pyside2/PySide2/QtWidgets/typesystem_widgets_common.xml
index 5de077181..9d3e70be2 100644
--- a/sources/pyside2/PySide2/QtWidgets/typesystem_widgets_common.xml
+++ b/sources/pyside2/PySide2/QtWidgets/typesystem_widgets_common.xml
@@ -3127,11 +3127,6 @@
     </modify-function>
   </object-type>
 
-  <!-- qApp macro -->
-  <inject-code class="native" position="beginning">
-    PyObject* moduleQtWidgets;
-  </inject-code>
-  <inject-code class="target" file="glue/qtwidgets_qapp.cpp" position="end" />
   <object-type name="QApplication">
     <enum-type name="ColorSpec"/>
     <extra-includes>
@@ -3151,48 +3146,6 @@
     </add-function>
     <modify-function signature="exec()" rename="exec_" allow-thread="yes"/>
     <inject-code class="native" file="glue/qapplication_init.cpp" position="beginning" />
-
-    <!-- ownership control transfer to qApp -->
-    <modify-function signature="setStyle(QStyle*)">
-        <inject-code class="target" position="end">
-            Shiboken::Object::setParent(%CONVERTTOPYTHON[QApplication*](qApp), %PYARG_1);
-        </inject-code>
-    </modify-function>
-    <modify-function signature="style()">
-      <inject-code class="target" position="end">
-        <insert-template name="set_qapp_parent_for_orphan"/>
-      </inject-code>
-    </modify-function>
-    <modify-function signature="desktop()">
-      <inject-code class="target" position="end">
-        <insert-template name="set_qapp_parent_for_orphan"/>
-      </inject-code>
-    </modify-function>
-    <modify-function signature="focusWidget()">
-      <inject-code class="target" position="end">
-        <insert-template name="set_qapp_parent_for_orphan"/>
-      </inject-code>
-    </modify-function>
-    <modify-function signature="topLevelAt(const QPoint&amp;)">
-      <inject-code class="target" position="end">
-        <insert-template name="set_qapp_parent_for_orphan"/>
-      </inject-code>
-    </modify-function>
-    <modify-function signature="topLevelAt(int, int)">
-      <inject-code class="target" position="end">
-        <insert-template name="set_qapp_parent_for_orphan"/>
-      </inject-code>
-    </modify-function>
-    <modify-function signature="widgetAt(const QPoint&amp;)">
-      <inject-code class="target" position="end">
-        <insert-template name="set_qapp_parent_for_orphan"/>
-      </inject-code>
-    </modify-function>
-    <modify-function signature="widgetAt(int, int)">
-      <inject-code class="target" position="end">
-        <insert-template name="set_qapp_parent_for_orphan"/>
-      </inject-code>
-    </modify-function>
   </object-type>
 
   <object-type name="QCommandLinkButton"/>
diff --git a/sources/pyside2/PySide2/typesystem_templates.xml b/sources/pyside2/PySide2/typesystem_templates.xml
index d9258ba88..7ac4ac158 100644
--- a/sources/pyside2/PySide2/typesystem_templates.xml
+++ b/sources/pyside2/PySide2/typesystem_templates.xml
@@ -297,13 +297,7 @@
     PyTuple_SET_ITEM(%PYARG_0, 0, %CONVERTTOPYTHON[%RETURN_TYPE](retval_));
     PyTuple_SET_ITEM(%PYARG_0, 1, %CONVERTTOPYTHON[%ARG5_TYPE](%5));
     </template>
-    <template name="set_qapp_parent_for_orphan">
-        if (%PYARG_0 &amp;&amp; (%PYARG_0 != Py_None)) {
-            SbkObject* _pySelf = reinterpret_cast&lt;SbkObject*&gt;(%PYARG_0);
-            if (!Shiboken::Object::hasParentInfo(_pySelf))
-                Shiboken::Object::setParent(%CONVERTTOPYTHON[QApplication*](qApp), %PYARG_0);
-        }
-    </template>
+
     <!-- templates for __repr__ -->
     <template name="repr_code">
         QString format = QString().sprintf("%s(%REPR_FORMAT)", ((PyObject*)%PYSELF)->ob_type->tp_name, %REPR_ARGS);