From 7ca5af28d0591ab34c6ce17ed7b9eff20cca1d67 Mon Sep 17 00:00:00 2001
From: Olivier Goffart <ogoffart@woboq.com>
Date: Tue, 12 Aug 2014 13:10:16 +0200
Subject: [PATCH] Fix error reported by address sanitizer
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

One can't dereference the null pointer value. Even to access a static member.

Change-Id: I5edc92d7886ccc7029d1f3c00a12de78b439f080
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>
---
 src/corelib/kernel/qobject.h | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/corelib/kernel/qobject.h b/src/corelib/kernel/qobject.h
index a54690606a..0b6c65ef95 100644
--- a/src/corelib/kernel/qobject.h
+++ b/src/corelib/kernel/qobject.h
@@ -156,13 +156,17 @@ public:
 
     template<typename T>
     inline T findChild(const QString &aName = QString(), Qt::FindChildOptions options = Qt::FindChildrenRecursively) const
-    { return static_cast<T>(qt_qFindChild_helper(this, aName, reinterpret_cast<T>(0)->staticMetaObject, options)); }
+    {
+        typedef typename QtPrivate::remove_cv<typename QtPrivate::remove_pointer<T>::type>::type ObjType;
+        return static_cast<T>(qt_qFindChild_helper(this, aName, ObjType::staticMetaObject, options));
+    }
 
     template<typename T>
     inline QList<T> findChildren(const QString &aName = QString(), Qt::FindChildOptions options = Qt::FindChildrenRecursively) const
     {
+        typedef typename QtPrivate::remove_cv<typename QtPrivate::remove_pointer<T>::type>::type ObjType;
         QList<T> list;
-        qt_qFindChildren_helper(this, aName, reinterpret_cast<T>(0)->staticMetaObject,
+        qt_qFindChildren_helper(this, aName, ObjType::staticMetaObject,
                                 reinterpret_cast<QList<void *> *>(&list), options);
         return list;
     }
@@ -171,8 +175,9 @@ public:
     template<typename T>
     inline QList<T> findChildren(const QRegExp &re, Qt::FindChildOptions options = Qt::FindChildrenRecursively) const
     {
+        typedef typename QtPrivate::remove_cv<typename QtPrivate::remove_pointer<T>::type>::type ObjType;
         QList<T> list;
-        qt_qFindChildren_helper(this, re, reinterpret_cast<T>(0)->staticMetaObject,
+        qt_qFindChildren_helper(this, re, ObjType::staticMetaObject,
                                 reinterpret_cast<QList<void *> *>(&list), options);
         return list;
     }
@@ -182,8 +187,9 @@ public:
     template<typename T>
     inline QList<T> findChildren(const QRegularExpression &re, Qt::FindChildOptions options = Qt::FindChildrenRecursively) const
     {
+        typedef typename QtPrivate::remove_cv<typename QtPrivate::remove_pointer<T>::type>::type ObjType;
         QList<T> list;
-        qt_qFindChildren_helper(this, re, reinterpret_cast<T>(0)->staticMetaObject,
+        qt_qFindChildren_helper(this, re, ObjType::staticMetaObject,
                                 reinterpret_cast<QList<void *> *>(&list), options);
         return list;
     }
@@ -519,7 +525,7 @@ inline T qobject_cast(QObject *object)
     typedef typename QtPrivate::remove_cv<typename QtPrivate::remove_pointer<T>::type>::type ObjType;
     Q_STATIC_ASSERT_X(QtPrivate::HasQ_OBJECT_Macro<ObjType>::Value,
                     "qobject_cast requires the type to have a Q_OBJECT macro");
-    return static_cast<T>(reinterpret_cast<T>(object)->staticMetaObject.cast(object));
+    return static_cast<T>(ObjType::staticMetaObject.cast(object));
 }
 
 template <class T>
@@ -528,7 +534,7 @@ inline T qobject_cast(const QObject *object)
     typedef typename QtPrivate::remove_cv<typename QtPrivate::remove_pointer<T>::type>::type ObjType;
     Q_STATIC_ASSERT_X(QtPrivate::HasQ_OBJECT_Macro<ObjType>::Value,
                       "qobject_cast requires the type to have a Q_OBJECT macro");
-    return static_cast<T>(reinterpret_cast<T>(object)->staticMetaObject.cast(object));
+    return static_cast<T>(ObjType::staticMetaObject.cast(object));
 }