Improvements to QValueList. This may relate to bug 1820

(cherry picked from commit 71a6d7870f)

src/tools/qvaluelist.h

@@ -233,12 +233,6 @@ public:
     QValueListPrivate();
     QValueListPrivate( const QValueListPrivate<T>& _p );
 
-    void derefAndDelete() // ### hack to get around hp-cc brain damage
-    {
-	if ( deref() )
-	    delete this;
-    }
-
 #if defined(Q_TEMPLATEDLL)
     // Workaround MS bug in memory de/allocation in DLL vs. EXE
     virtual
@@ -261,14 +255,14 @@ public:
 template <class T>
 Q_INLINE_TEMPLATES QValueListPrivate<T>::QValueListPrivate()
 {
-    node = new Node; node->next = node->prev = node; nodes = 0;
+    node = new Node(); node->next = node->prev = node; nodes = 0;
 }
 
 template <class T>
 Q_INLINE_TEMPLATES QValueListPrivate<T>::QValueListPrivate( const QValueListPrivate<T>& _p )
     : QShared()
 {
-    node = new Node; node->next = node->prev = node; nodes = 0;
+    node = new Node(); node->next = node->prev = node; nodes = 0;
     Iterator b( _p.node->next );
     Iterator e( _p.node );
     Iterator i( node );
@@ -442,15 +436,23 @@ public:
 	qCopy( l.begin(), l.end(), std::back_inserter( *this ) );
     }
 #endif
-    ~QValueList() { sh->derefAndDelete(); }
+    ~QValueList()
+    {
+        if (sh->deref())
+	    delete sh;
+    }
 
     QValueList<T>& operator= ( const QValueList<T>& l )
     {
+        if (this == &l || sh == l.sh)
+            return *this;  // Do nothing is self-assigning
 	l.sh->ref();
-	sh->derefAndDelete();
+        if (sh->deref())
+	    delete sh;
 	sh = l.sh;
 	return *this;
     }
+    
 #ifndef QT_NO_STL
     QValueList<T>& operator= ( const std::list<T>& l )
     {
@@ -458,6 +460,7 @@ public:
 	qCopy( l.begin(), l.end(), std::back_inserter( *this ) );
 	return *this;
     }
+    
     bool operator== ( const std::list<T>& l ) const
     {
 	if ( size() != l.size() )
@@ -563,7 +566,14 @@ protected:
     /**
      * Helpers
      */
-    void detach() { if ( sh->count > 1 ) detachInternal(); }
+    void detach()
+    { 
+        if (sh->count > 1) 
+        {
+            sh->deref();
+            sh = new QValueListPrivate<T>(*sh);        
+        }
+    }
 
     /**
      * Variables
@@ -571,8 +581,6 @@ protected:
     QValueListPrivate<T>* sh;
 
 private:
-    void detachInternal();
-
     friend class QDeepCopy< QValueList<T> >;
 };
 
@@ -592,7 +600,7 @@ Q_INLINE_TEMPLATES bool QValueList<T>::operator== ( const QValueList<T>& l ) con
 template <class T>
 Q_INLINE_TEMPLATES void QValueList<T>::clear()
 {
-    if ( sh->count == 1 ) sh->clear(); else { sh->deref(); sh = new QValueListPrivate<T>; }
+    if ( sh->count == 1 ) sh->clear(); else { sh->deref(); sh = new QValueListPrivate<T>(); }
 }
 
 template <class T>
@@ -629,12 +637,6 @@ Q_INLINE_TEMPLATES QValueList<T>& QValueList<T>::operator+= ( const QValueList<T
     return *this;
 }
 
-template <class T>
-Q_INLINE_TEMPLATES void QValueList<T>::detachInternal()
-{
-    sh->deref(); sh = new QValueListPrivate<T>( *sh );
-}
-
 #ifndef QT_NO_DATASTREAM
 template <class T>
 Q_INLINE_TEMPLATES QDataStream& operator>>( QDataStream& s, QValueList<T>& l )