Remove QMetaObject guards and deprecate QPointer.

QWeakPointer is superior and preferred.

Remove QMetaObject::addGuard(), QMetaObject::changeGuard(),
QMetaObject::removeGuard(), and QObjectPrivate::clearGuards().

Implement QPointer using QWeakPointer<T> instead. This changes the
behavior of QPointer in 2 ways:

- During destruction of a QWidget. Previously, the destructor of QWidget
would reset all QPointers so that they would return zero when destroying
children. Update tst_QPointer to account for this change.

- When constructing a QSharedPointer to take ownership of an object
after a QPointer is already tracking the object. Previously, the shared
pointer construction would not be affected by the QPointer, but now
that QPointer is implemented using QWeakPoiner, constructing the
QSharedPointer will cause an abort(). Fix tst_QSharedPointer by
removing the use of QPointer in the objectCast() test.

These behavior changes are documented in the QPointer class
documentation and in the changes file.

Change-Id: I92d0276219c076ece7bcb60f6e1b9120ce4f5747
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

1 files changed, 20 insertions, 17 deletions

diff --git a/src/corelib/kernel/qpointer.h b/src/corelib/kernel/qpointer.h
index e9f302e317..a1d1f2037f 100644
--- a/src/corelib/kernel/qpointer.h
+++ b/src/corelib/kernel/qpointer.h
@@ -42,7 +42,7 @@
 #ifndef QPOINTER_H
 #define QPOINTER_H
 
-#include <QtCore/qobject.h>
+#include <QtCore/qsharedpointer.h>
 
 QT_BEGIN_HEADER
 
@@ -50,34 +50,35 @@ QT_BEGIN_NAMESPACE
 
 QT_MODULE(Core)
 
+#if QT_DEPRECATED_SINCE(5,0)
+
 template <class T>
-class QPointer
+class QT_DEPRECATED QPointer
 {
-    QObject *o;
+    QWeakPointer<T> wp;
+
 public:
-    inline QPointer() : o(0) {}
-    inline QPointer(T *p) : o(p)
-        { QMetaObject::addGuard(&o); }
-    inline QPointer(const QPointer<T> &p) : o(p.o)
-        { QMetaObject::addGuard(&o); }
-    inline ~QPointer()
-        { QMetaObject::removeGuard(&o); }
+    inline QPointer() : wp() { }
+    inline QPointer(T *p) : wp(p) { }
+    inline QPointer(const QPointer<T> &p) : wp(p.wp) { }
+    inline ~QPointer() { }
+
     inline QPointer<T> &operator=(const QPointer<T> &p)
-        { if (this != &p) QMetaObject::changeGuard(&o, p.o); return *this; }
+    { wp = p.wp; return *this; }
     inline QPointer<T> &operator=(T* p)
-        { if (o != p) QMetaObject::changeGuard(&o, p); return *this; }
+    { wp = p; return *this; }
 
     inline bool isNull() const
-        { return !o; }
+    { return wp.isNull(); }
 
     inline T* operator->() const
-        { return static_cast<T*>(const_cast<QObject*>(o)); }
+    { return wp.data(); }
     inline T& operator*() const
-        { return *static_cast<T*>(const_cast<QObject*>(o)); }
+    { return *wp.data(); }
     inline operator T*() const
-        { return static_cast<T*>(const_cast<QObject*>(o)); }
+    { return wp.data(); }
     inline T* data() const
-        { return static_cast<T*>(const_cast<QObject*>(o)); }
+    { return wp.data(); }
 };
 
 
@@ -161,6 +162,8 @@ inline bool operator!= (int i, const QPointer<T> &p)
 { Q_ASSERT(i == 0); return !i && !p.isNull(); }
 #endif
 
+#endif // QT_DEPRECATED_SINCE(5,0)
+
 QT_END_NAMESPACE
 
 QT_END_HEADER