2 files changed, 42 insertions, 4 deletions

diff --git a/src/corelib/tools/qlist.cpp b/src/corelib/tools/qlist.cpp
index ac0dc46..a468c77 100644
--- a/src/corelib/tools/qlist.cpp
+++ b/src/corelib/tools/qlist.cpp
@@ -154,6 +154,19 @@ QListData::Data *QListData::detach(int alloc)
 }
 
 /*!
+ *  Detaches the QListData by allocating new memory for a list which will be bigger
+ *  than the copied one and is expected to grow further.
+ *  Returns the old (shared) data, it is up to the caller to deref() and free()
+ *  For the new data node_copy needs to be called.
+ *
+ *  \internal
+ */
+QListData::Data *QListData::detach_grow(int alloc)
+{
+    return detach(grow(alloc));
+}
+
+/*!
  *  Detaches the QListData by reallocating new memory.
  *  Returns the old (shared) data, it is up to the caller to deref() and free()
  *  For the new data node_copy needs to be called.
@@ -596,6 +609,11 @@ void **QListData::erase(void **xi)
     \internal
 */
 
+/*! \fn void QList::detach_grow(int alloc)
+
+    \internal
+*/
+
 /*! \fn void QList::detachShared()
 
     \internal
diff --git a/src/corelib/tools/qlist.h b/src/corelib/tools/qlist.h
index 8c75c98..1edac03 100644
--- a/src/corelib/tools/qlist.h
+++ b/src/corelib/tools/qlist.h
@@ -73,6 +73,7 @@ struct Q_CORE_EXPORT QListData {
     enum { DataHeaderSize = sizeof(Data) - sizeof(void *) };
 
     Data *detach(int alloc);
+    Data *detach_grow(int alloc);
     Data *detach(); // remove in 5.0
     Data *detach2(); // remove in 5.0
     Data *detach3(); // remove in 5.0
@@ -121,6 +122,7 @@ public:
     inline int size() const { return p.size(); }
 
     inline void detach() { if (d->ref != 1) detach_helper(); }
+    inline void detach_grow(int by) { if (d->ref != 1) detach_helper_grow(d->end - d->begin + by); }
 
     inline void detachShared()
     {
@@ -333,6 +335,7 @@ public:
 #endif
 
 private:
+    void detach_helper_grow(int alloc);
     void detach_helper(int alloc);
     void detach_helper();
     void free(QListData::Data *d);
@@ -480,7 +483,7 @@ Q_OUTOFLINE_TEMPLATE void QList<T>::reserve(int alloc)
 template <typename T>
 Q_OUTOFLINE_TEMPLATE void QList<T>::append(const T &t)
 {
-    detach();
+    detach_grow(1);
     if (QTypeInfo<T>::isLarge || QTypeInfo<T>::isStatic) {
         Node *n = reinterpret_cast<Node *>(p.append());
         QT_TRY {
@@ -504,7 +507,7 @@ Q_OUTOFLINE_TEMPLATE void QList<T>::append(const T &t)
 template <typename T>
 inline void QList<T>::prepend(const T &t)
 {
-    detach();
+    detach_grow(1);
     if (QTypeInfo<T>::isLarge || QTypeInfo<T>::isStatic) {
         Node *n = reinterpret_cast<Node *>(p.prepend());
         QT_TRY {
@@ -528,7 +531,7 @@ inline void QList<T>::prepend(const T &t)
 template <typename T>
 inline void QList<T>::insert(int i, const T &t)
 {
-    detach();
+    detach_grow(1);
     if (QTypeInfo<T>::isLarge || QTypeInfo<T>::isStatic) {
         Node *n = reinterpret_cast<Node *>(p.insert(i));
         QT_TRY {
@@ -622,6 +625,23 @@ Q_OUTOFLINE_TEMPLATE T QList<T>::value(int i, const T& defaultValue) const
 }
 
 template <typename T>
+Q_OUTOFLINE_TEMPLATE void QList<T>::detach_helper_grow(int alloc)
+{
+    Node *n = reinterpret_cast<Node *>(p.begin());
+    QListData::Data *x = p.detach_grow(alloc);
+    QT_TRY {
+        node_copy(reinterpret_cast<Node *>(p.begin()), reinterpret_cast<Node *>(p.end()), n);
+    } QT_CATCH(...) {
+        qFree(d);
+        d = x;
+        QT_RETHROW;
+    }
+
+    if (!x->ref.deref())
+        free(x);
+}
+
+template <typename T>
 Q_OUTOFLINE_TEMPLATE void QList<T>::detach_helper(int alloc)
 {
     Node *n = reinterpret_cast<Node *>(p.begin());
@@ -730,7 +750,7 @@ Q_OUTOFLINE_TEMPLATE typename QList<T>::iterator QList<T>::erase(typename QList<
 template <typename T>
 Q_OUTOFLINE_TEMPLATE QList<T> &QList<T>::operator+=(const QList<T> &l)
 {
-    detach();
+    detach_grow(l.size());
     Node *n = reinterpret_cast<Node *>(p.append2(l.p));
     QT_TRY{
         node_copy(n, reinterpret_cast<Node *>(p.end()), reinterpret_cast<Node *>(l.p.begin()));