Use QPersistentModelIndex for storing a model index

QModelIndex is not safe to be used to store an index as it is designed
to be discarded right after use as the index information can change.

Therefore a QPersistentModelIndex should be used instead to store the
index. Subsequently the m_index does not need to be updated whenever
the model changes anymore as this is already done for us.

Task-number: QTBUG-49907
Change-Id: Icc93e410de2821c503ea15a7a1dd9ae32634914e
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

3 files changed, 12 insertions, 37 deletions

diff --git a/src/widgets/accessible/itemviews.cpp b/src/widgets/accessible/itemviews.cpp
index 1b724c9a17..d58db8de32 100644
--- a/src/widgets/accessible/itemviews.cpp
+++ b/src/widgets/accessible/itemviews.cpp
@@ -550,20 +550,8 @@ void QAccessibleTable::modelChange(QAccessibleTableModelChangeEvent *event)
             QAccessible::Id id = iter.value();
             QAccessibleInterface *iface = QAccessible::accessibleInterface(id);
             Q_ASSERT(iface);
-            if (iface->role() == QAccessible::Cell || iface->role() == QAccessible::ListItem) {
-                Q_ASSERT(iface->tableCellInterface());
-                QAccessibleTableCell *cell = static_cast<QAccessibleTableCell*>(iface->tableCellInterface());
-                if (event->modelChangeType() == QAccessibleTableModelChangeEvent::RowsInserted
-                        && cell->m_index.row() >= event->firstRow()) {
-                    int newRow = cell->m_index.row() + newRows;
-                    cell->m_index = cell->m_index.sibling(newRow, cell->m_index.column());
-                } else if (event->modelChangeType() == QAccessibleTableModelChangeEvent::ColumnsInserted
-                        && cell->m_index.column() >= event->firstColumn()) {
-                    int newColumn = cell->m_index.column() + newColumns;
-                    cell->m_index = cell->m_index.sibling(cell->m_index.row(), newColumn);
-                }
-            } else if (event->modelChangeType() == QAccessibleTableModelChangeEvent::RowsInserted
-                       && iface->role() == QAccessible::RowHeader) {
+            if (event->modelChangeType() == QAccessibleTableModelChangeEvent::RowsInserted
+                && iface->role() == QAccessible::RowHeader) {
                 QAccessibleTableHeaderCell *cell = static_cast<QAccessibleTableHeaderCell*>(iface);
                 if (cell->index >= event->firstRow()) {
                     cell->index += newRows;
@@ -602,27 +590,11 @@ void QAccessibleTable::modelChange(QAccessibleTableModelChangeEvent *event)
             if (iface->role() == QAccessible::Cell || iface->role() == QAccessible::ListItem) {
                 Q_ASSERT(iface->tableCellInterface());
                 QAccessibleTableCell *cell = static_cast<QAccessibleTableCell*>(iface->tableCellInterface());
-                if (event->modelChangeType() == QAccessibleTableModelChangeEvent::RowsRemoved) {
-                    if (cell->m_index.row() < event->firstRow()) {
-                        newCache.insert(indexOfChild(cell), id);
-                    } else if (cell->m_index.row() > event->lastRow()) {
-                        int newRow = cell->m_index.row() - deletedRows;
-                        cell->m_index = cell->m_index.sibling(newRow, cell->m_index.column());
-                        newCache.insert(indexOfChild(cell), id);
-                    } else {
-                        QAccessible::deleteAccessibleInterface(id);
-                    }
-                } else if (event->modelChangeType() == QAccessibleTableModelChangeEvent::ColumnsRemoved) {
-                    if (cell->m_index.column() < event->firstColumn()) {
-                        newCache.insert(indexOfChild(cell), id);
-                    } else if (cell->m_index.column() > event->lastColumn()) {
-                        int newColumn = cell->m_index.column() - deletedColumns;
-                        cell->m_index = cell->m_index.sibling(cell->m_index.row(), newColumn);
-                        newCache.insert(indexOfChild(cell), id);
-                    } else {
-                        QAccessible::deleteAccessibleInterface(id);
-                    }
-                }
+                // Since it is a QPersistentModelIndex, we only need to check if it is valid
+                if (cell->m_index.isValid())
+                    newCache.insert(indexOfChild(cell), id);
+                else
+                    QAccessible::deleteAccessibleInterface(id);
             } else if (event->modelChangeType() == QAccessibleTableModelChangeEvent::RowsRemoved
                        && iface->role() == QAccessible::RowHeader) {
                 QAccessibleTableHeaderCell *cell = static_cast<QAccessibleTableHeaderCell*>(iface);
diff --git a/src/widgets/accessible/itemviews_p.h b/src/widgets/accessible/itemviews_p.h
index 6a18a1231b..b3cd456585 100644
--- a/src/widgets/accessible/itemviews_p.h
+++ b/src/widgets/accessible/itemviews_p.h
@@ -207,7 +207,7 @@ private:
     QHeaderView *verticalHeader() const;
     QHeaderView *horizontalHeader() const;
     QPointer<QAbstractItemView > view;
-    QModelIndex m_index;
+    QPersistentModelIndex m_index;
     QAccessible::Role m_role;
 
     void selectCell();
diff --git a/tests/auto/other/qaccessibility/tst_qaccessibility.cpp b/tests/auto/other/qaccessibility/tst_qaccessibility.cpp
index 62c2c0a916..3d78749024 100644
--- a/tests/auto/other/qaccessibility/tst_qaccessibility.cpp
+++ b/tests/auto/other/qaccessibility/tst_qaccessibility.cpp
@@ -2903,7 +2903,10 @@ void tst_QAccessibility::listTest()
     QAccessibleInterface *cellMunich3 = table2->cellAt(2,0);
     QCOMPARE(cell4, cellMunich3);
     QCOMPARE(axidMunich, QAccessible::uniqueId(cellMunich3));
-
+    delete listView->takeItem(2);
+    // list: Oslo, Helsinki
+    // verify that it doesn't return an invalid item from the cache
+    QVERIFY(table2->cellAt(2,0) == 0);
 
     delete listView;
     }