1 files changed, 13 insertions, 8 deletions
diff --git a/src/widgets/itemviews/qtreewidget.cpp b/src/widgets/itemviews/qtreewidget.cpp
index b253abac73..de7f7c0b77 100644
--- a/src/widgets/itemviews/qtreewidget.cpp
+++ b/src/widgets/itemviews/qtreewidget.cpp
@@ -145,7 +145,7 @@ QTreeModel::QTreeModel(QTreeModelPrivate &dd, QTreeWidget *parent)
 QTreeModel::~QTreeModel()
 {
     clear();
-    headerItem->view = Q_NULLPTR;
+    headerItem->view = nullptr;
     delete headerItem;
     rootItem->view = 0;
     delete rootItem;
@@ -2012,6 +2012,9 @@ void QTreeWidgetItem::addChildren(const QList<QTreeWidgetItem*> &children)
 */
 void QTreeWidgetItem::insertChildren(int index, const QList<QTreeWidgetItem*> &children)
 {
+    if (index < 0 || index > this->children.count() || children.isEmpty())
+        return;
+
     if (view && view->isSortingEnabled()) {
         for (int n = 0; n < children.count(); ++n)
             insertChild(index, children.at(n));
@@ -2729,14 +2732,14 @@ void QTreeWidget::setHeaderItem(QTreeWidgetItem *item)
 
     int oldCount = columnCount();
     if (oldCount < item->columnCount())
-         d->treeModel()->beginInsertColumns(QModelIndex(), oldCount, item->columnCount());
-    else
-         d->treeModel()->beginRemoveColumns(QModelIndex(), item->columnCount(), oldCount);
+         d->treeModel()->beginInsertColumns(QModelIndex(), oldCount, item->columnCount() - 1);
+    else if (oldCount > item->columnCount())
+         d->treeModel()->beginRemoveColumns(QModelIndex(), item->columnCount(), oldCount - 1);
     delete d->treeModel()->headerItem;
     d->treeModel()->headerItem = item;
     if (oldCount < item->columnCount())
         d->treeModel()->endInsertColumns();
-    else
+    else if (oldCount > item->columnCount())
         d->treeModel()->endRemoveColumns();
     d->treeModel()->headerDataChanged(Qt::Horizontal, 0, oldCount);
 }
@@ -2859,11 +2862,11 @@ QRect QTreeWidget::visualItemRect(const QTreeWidgetItem *item) const
     Q_D(const QTreeWidget);
     //the visual rect for an item is across all columns. So we need to determine
     //what is the first and last column and get their visual index rects
-    QModelIndex base = d->index(item);
+    const QModelIndex base = d->index(item);
     const int firstVisiblesection = header()->logicalIndexAt(- header()->offset());
     const int lastVisibleSection = header()->logicalIndexAt(header()->length() - header()->offset() - 1);
-    QModelIndex first = base.sibling(base.row(), header()->logicalIndex(firstVisiblesection));
-    QModelIndex last = base.sibling(base.row(), header()->logicalIndex(lastVisibleSection));
+    const QModelIndex first = base.sibling(base.row(), firstVisiblesection);
+    const QModelIndex last = base.sibling(base.row(), lastVisibleSection);
     return visualRect(first) | visualRect(last);
 }
 
@@ -3369,6 +3372,7 @@ QModelIndex QTreeWidget::indexFromItem(const QTreeWidgetItem *item, int column)
     return d->index(item, column);
 }
 
+#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
 /*!
     \overload
     \internal
@@ -3377,6 +3381,7 @@ QModelIndex QTreeWidget::indexFromItem(QTreeWidgetItem *item, int column) const
 {
     return indexFromItem(const_cast<const QTreeWidgetItem *>(item), column);
 }
+#endif
 
 /*!
     Returns a pointer to the QTreeWidgetItem associated with the given \a index.