QObject: port to new property system

Extended QObjectPrivate::ExtraData to store a pointer
to its parent, and reimplemented qGetBindingStorage()
function for QObjectPrivate::ExtraData.
This allows to use Q_OBJECT_COMPAT_PROPERTY macro
for a property, stored in QObjectPrivate::ExtraData
and solves all the problems with calling a custom
setter.

Task-number: QTBUG-85520
Change-Id: I40e01c29430846359ef9160fa1ae97c702be9a18
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io>

src/corelib/global/qhooks.cpp

@@ -67,7 +67,7 @@ quintptr Q_CORE_EXPORT qtHookData[] = {
     // The required sizes and offsets are tested in tests/auto/other/toolsupport.
     // When this fails and the change was intentional, adjust the test and
     // adjust this value here.
-    20
+    21
 };
 
 static_assert(QHooks::LastHookIndex == sizeof(qtHookData) / sizeof(qtHookData[0]));

src/corelib/kernel/qobject.cpp

@@ -1214,6 +1214,11 @@ QObjectPrivate::Connection::~Connection()
 QString QObject::objectName() const
 {
     Q_D(const QObject);
+    if (!d->extraData && QtPrivate::isAnyBindingEvaluating()) {
+        QObjectPrivate *dd = const_cast<QObjectPrivate *>(d);
+        // extraData is mutable, so this should be safe
+        dd->extraData = new QObjectPrivate::ExtraData(dd);
+    }
     return d->extraData ? d->extraData->objectName : QString();
 }
 
@@ -1223,15 +1228,28 @@ QString QObject::objectName() const
 void QObject::setObjectName(const QString &name)
 {
     Q_D(QObject);
+
     if (!d->extraData)
-        d->extraData = new QObjectPrivate::ExtraData;
+        d->extraData = new QObjectPrivate::ExtraData(d);
+
+    d->extraData->objectName.removeBindingUnlessInWrapper();
 
     if (d->extraData->objectName != name) {
-        d->extraData->objectName = name;
-        emit objectNameChanged(d->extraData->objectName, QPrivateSignal());
+        d->extraData->objectName.setValueBypassingBindings(name);
+        d->extraData->objectName.notify(); // also emits a signal
     }
 }
 
+QBindable<QString> QObject::bindableObjectName()
+{
+    Q_D(QObject);
+
+    if (!d->extraData)
+        d->extraData = new QObjectPrivate::ExtraData(d);
+
+    return QBindable<QString>(&d->extraData->objectName);
+}
+
 /*! \fn void QObject::objectNameChanged(const QString &objectName)
 
     This signal is emitted after the object's name has been changed. The new object name is passed as \a objectName.
@@ -1731,7 +1749,7 @@ int QObject::startTimer(int interval, Qt::TimerType timerType)
     }
     int timerId = thisThreadData->eventDispatcher.loadRelaxed()->registerTimer(interval, timerType, this);
     if (!d->extraData)
-        d->extraData = new QObjectPrivate::ExtraData;
+        d->extraData = new QObjectPrivate::ExtraData(d);
     d->extraData->runningTimers.append(timerId);
     return timerId;
 }
@@ -2164,7 +2182,7 @@ void QObject::installEventFilter(QObject *obj)
     }
 
     if (!d->extraData)
-        d->extraData = new QObjectPrivate::ExtraData;
+        d->extraData = new QObjectPrivate::ExtraData(d);
 
     // clean up unused items in the list
     d->extraData->eventFilters.removeAll((QObject *)nullptr);
@@ -3971,7 +3989,7 @@ bool QObject::setProperty(const char *name, const QVariant &value)
     int id = meta->indexOfProperty(name);
     if (id < 0) {
         if (!d->extraData)
-            d->extraData = new QObjectPrivate::ExtraData;
+            d->extraData = new QObjectPrivate::ExtraData(d);
 
         const int idx = d->extraData->propertyNames.indexOf(name);
 

src/corelib/kernel/qobject.h

@@ -120,7 +120,8 @@ class Q_CORE_EXPORT QObject
 {
     Q_OBJECT
 
-    Q_PROPERTY(QString objectName READ objectName WRITE setObjectName NOTIFY objectNameChanged)
+    Q_PROPERTY(QString objectName READ objectName WRITE setObjectName NOTIFY objectNameChanged
+                       BINDABLE bindableObjectName)
     Q_DECLARE_PRIVATE(QObject)
 
 public:
@@ -137,6 +138,7 @@ public:
 
     QString objectName() const;
     void setObjectName(const QString &name);
+    QBindable<QString> bindableObjectName();
 
     inline bool isWidgetType() const { return d_ptr->isWidget; }
     inline bool isWindowType() const { return d_ptr->isWindow; }

src/corelib/kernel/qobject_p.h

@@ -61,6 +61,7 @@
 #include "QtCore/qsharedpointer.h"
 #include "QtCore/qvariant.h"
 #include "QtCore/qproperty.h"
+#include "QtCore/private/qproperty_p.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -102,12 +103,26 @@ class Q_CORE_EXPORT QObjectPrivate : public QObjectData
 public:
     struct ExtraData
     {
-        ExtraData() {}
+        ExtraData(QObjectPrivate *ptr) : parent(ptr) { }
+
+        inline void setObjectNameForwarder(const QString &name)
+        {
+            parent->q_func()->setObjectName(name);
+        }
+
+        inline void nameChangedForwarder(const QString &name)
+        {
+            emit parent->q_func()->objectNameChanged(name, QObject::QPrivateSignal());
+        }
+
         QList<QByteArray> propertyNames;
         QList<QVariant> propertyValues;
         QList<int> runningTimers;
         QList<QPointer<QObject>> eventFilters;
-        QString objectName;
+        Q_OBJECT_COMPAT_PROPERTY(QObjectPrivate::ExtraData, QString, objectName,
+                                 &QObjectPrivate::ExtraData::setObjectNameForwarder,
+                                 &QObjectPrivate::ExtraData::nameChangedForwarder)
+        QObjectPrivate *parent;
     };
 
     typedef void (*StaticMetaCallFunction)(QObject *, QMetaObject::Call, int, void **);
@@ -369,8 +384,9 @@ public:
         cd->ref.ref();
         connections.storeRelaxed(cd);
     }
+
 public:
-    ExtraData *extraData;    // extra data set by the user
+    mutable ExtraData *extraData; // extra data set by the user
     // This atomic requires acquire/release semantics in a few places,
     // e.g. QObject::moveToThread must synchronize with QCoreApplication::postEvent,
     // because postEvent is thread-safe.
@@ -619,7 +635,14 @@ inline QBindingStorage *qGetBindingStorage(QObjectPrivate *o)
 {
     return &o->bindingStorage;
 }
-
+inline const QBindingStorage *qGetBindingStorage(const QObjectPrivate::ExtraData *ed)
+{
+    return &ed->parent->bindingStorage;
+}
+inline QBindingStorage *qGetBindingStorage(QObjectPrivate::ExtraData *ed)
+{
+    return &ed->parent->bindingStorage;
+}
 
 QT_END_NAMESPACE
 

tests/auto/corelib/kernel/qobject/CMakeLists.txt

@@ -9,9 +9,10 @@ qt_internal_add_test(tst_qobject
         tst_qobject.cpp
     DEFINES
         QT_DISABLE_DEPRECATED_BEFORE=0
-    PUBLIC_LIBRARIES
+    LIBRARIES
         Qt::CorePrivate
         Qt::Network
+        Qt::TestPrivate
 )
 
 ## Scopes:

tests/auto/corelib/kernel/qobject/tst_qobject.cpp

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2021 The Qt Company Ltd.
 ** Copyright (C) 2015 Olivier Goffart <ogoffart@woboq.com>
 ** Contact: https://www.qt.io/licensing/
 **
@@ -28,6 +28,7 @@
 ****************************************************************************/
 
 #include <QTest>
+#include <QtTest/private/qpropertytesthelper_p.h>
 #include <QStringListModel>
 #include <QAbstractEventDispatcher>
 #include <QScopedValueRollback>
@@ -161,6 +162,7 @@ private slots:
     void functorReferencesConnection();
     void disconnectDisconnects();
     void singleShotConnection();
+    void objectNameBinding();
 };
 
 struct QObjectCreatedOnShutdown
@@ -8115,6 +8117,13 @@ void tst_QObject::singleShotConnection()
     }
 }
 
+void tst_QObject::objectNameBinding()
+{
+    QObject obj;
+    QTestPrivate::testReadWritePropertyBasics<QObject, QString>(obj, "test1", "test2",
+                                                                "objectName");
+}
+
 // Test for QtPrivate::HasQ_OBJECT_Macro
 static_assert(QtPrivate::HasQ_OBJECT_Macro<tst_QObject>::Value);
 static_assert(!QtPrivate::HasQ_OBJECT_Macro<SiblingDeleter>::Value);

tests/auto/other/toolsupport/tst_toolsupport.cpp

@@ -109,7 +109,7 @@ void tst_toolsupport::offsets_data()
         QTestData &data = QTest::newRow("sizeof(QObjectPrivate::ExtraData)")
                 << sizeof(QObjectPrivate::ExtraData);
         // Please heed the comment at the top of this file when changing this line:
-        data << 60 << 120; // 4 * QList + 1 * QString
+        data << 64 << 128; // 4 * QList + 1 * QString + ptr
     }
 
 #if RUN_MEMBER_OFFSET_TEST