QStandardItem: Fix reset parent in takeItem()

After the change for QTBUG-89145 the parent was not set to 0 when the
item was not attached to a model.

Pick-to: 6.5 6.2
Fixes: QTBUG-117900
Task-number: QTBUG-89145
Change-Id: I421e775130b03ce3eb2dd1dd05370e7391af087b
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit 0416e080cffe33de435631b5d47d3acbbcb7b880)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

2 files changed, 53 insertions, 19 deletions

diff --git a/src/gui/itemmodels/qstandarditemmodel.cpp b/src/gui/itemmodels/qstandarditemmodel.cpp
index 6eee1cdbf4..ee01da4bc1 100644
--- a/src/gui/itemmodels/qstandarditemmodel.cpp
+++ b/src/gui/itemmodels/qstandarditemmodel.cpp
@@ -1858,28 +1858,30 @@ QStandardItem *QStandardItem::takeChild(int row, int column)
     if (index != -1) {
         QModelIndex changedIdx;
         item = d->children.at(index);
-        if (item && d->model) {
+        if (item) {
             QStandardItemPrivate *const item_d = item->d_func();
-            const int savedRows = item_d->rows;
-            const int savedCols = item_d->columns;
-            const QVector<QStandardItem*> savedChildren = item_d->children;
-            if (savedRows > 0) {
-                d->model->d_func()->rowsAboutToBeRemoved(item, 0, savedRows - 1);
-                item_d->rows = 0;
-                item_d->children = QVector<QStandardItem*>(); //slightly faster than clear
-                d->model->d_func()->rowsRemoved(item, 0, savedRows);
-            }
-            if (savedCols > 0) {
-                d->model->d_func()->columnsAboutToBeRemoved(item, 0, savedCols - 1);
-                item_d->columns = 0;
-                if (!item_d->children.isEmpty())
+            if (d->model) {
+                QStandardItemModelPrivate *const model_d = d->model->d_func();
+                const int savedRows = item_d->rows;
+                const int savedCols = item_d->columns;
+                const QVector<QStandardItem*> savedChildren = item_d->children;
+                if (savedRows > 0) {
+                    model_d->rowsAboutToBeRemoved(item, 0, savedRows - 1);
+                    item_d->rows = 0;
                     item_d->children = QVector<QStandardItem*>(); //slightly faster than clear
-                d->model->d_func()->columnsRemoved(item, 0, savedCols);
+                    model_d->rowsRemoved(item, 0, savedRows);
+                }
+                if (savedCols > 0) {
+                    model_d->columnsAboutToBeRemoved(item, 0, savedCols - 1);
+                    item_d->columns = 0;
+                    item_d->children = QVector<QStandardItem*>(); //slightly faster than clear
+                    model_d->columnsRemoved(item, 0, savedCols);
+                }
+                item_d->rows = savedRows;
+                item_d->columns = savedCols;
+                item_d->children = savedChildren;
+                changedIdx = d->model->indexFromItem(item);
             }
-            item_d->rows = savedRows;
-            item_d->columns = savedCols;
-            item_d->children = savedChildren;
-            changedIdx = d->model->indexFromItem(item);
             item_d->setParentAndModel(nullptr, nullptr);
         }
         d->children.replace(index, nullptr);
diff --git a/tests/auto/gui/itemmodels/qstandarditemmodel/tst_qstandarditemmodel.cpp b/tests/auto/gui/itemmodels/qstandarditemmodel/tst_qstandarditemmodel.cpp
index f5f02761d5..7489b7bf13 100644
--- a/tests/auto/gui/itemmodels/qstandarditemmodel/tst_qstandarditemmodel.cpp
+++ b/tests/auto/gui/itemmodels/qstandarditemmodel/tst_qstandarditemmodel.cpp
@@ -120,6 +120,7 @@ private slots:
     void taskQTBUG_45114_setItemData();
     void setItemPersistentIndex();
     void signalsOnTakeItem();
+    void takeChild();
     void createPersistentOnLayoutAboutToBeChanged();
 private:
     QStandardItemModel *m_model = nullptr;
@@ -1828,5 +1829,36 @@ void tst_QStandardItemModel::createPersistentOnLayoutAboutToBeChanged() // QTBUG
     QCOMPARE(layoutChangedSpy.size(), 1);
 }
 
+void tst_QStandardItemModel::takeChild()  // QTBUG-117900
+{
+  {
+      // with model
+      QStandardItemModel model1;
+      QStandardItemModel model2;
+      QStandardItem base1("base1");
+      model1.setItem(0, 0, &base1);
+      QStandardItem base2("base2");
+      model2.setItem(0, 0, &base2);
+      auto item = new QStandardItem("item1");
+      item->appendRow({new QStandardItem("child")});
+      base1.appendRow({item});
+      base2.appendRow({base1.takeChild(0, 0)});
+      QCOMPARE(base1.child(0, 0), nullptr);
+      QCOMPARE(base2.child(0, 0), item);
+  }
+  {
+      // without model
+      QStandardItem base1("base1");
+      QStandardItem base2("base2");
+      auto item = new QStandardItem("item1");
+      item->appendRow({new QStandardItem("child")});
+      base1.appendRow({item});
+      base2.appendRow({base1.takeChild(0, 0)});
+      QCOMPARE(base1.child(0, 0), nullptr);
+      QCOMPARE(base2.child(0, 0), item);
+  }
+}
+
+
 QTEST_MAIN(tst_QStandardItemModel)
 #include "tst_qstandarditemmodel.moc"