QSortFilterProxyModel: don't assert when old model gets destroyed

When a new model was set with setSourceModel() and the mapping was
built up, the destruction of the old model caused a reset in the
QSortFilterProxyModel which lead to an empty view or an assertion.
Now we properly disconnect the old model again and also clean up the old
mapping/persistent indexes when a new source model is set.

Task-number: QTBUG-44962
Task-number: QTBUG-67948
Task-number: QTBUG-68427
Change-Id: I2e0612899c210bde3ac0cfa59aefd78269deee5b
Reviewed-by: David Faure <david.faure@kdab.com>

2 files changed, 18 insertions, 5 deletions

diff --git a/src/corelib/itemmodels/qsortfilterproxymodel.cpp b/src/corelib/itemmodels/qsortfilterproxymodel.cpp
index 78093727b8..08279cb244 100644
--- a/src/corelib/itemmodels/qsortfilterproxymodel.cpp
+++ b/src/corelib/itemmodels/qsortfilterproxymodel.cpp
@@ -1910,7 +1910,10 @@ void QSortFilterProxyModel::setSourceModel(QAbstractItemModel *sourceModel)
     disconnect(d->model, SIGNAL(modelAboutToBeReset()), this, SLOT(_q_sourceAboutToBeReset()));
     disconnect(d->model, SIGNAL(modelReset()), this, SLOT(_q_sourceReset()));
 
-    d->_q_sourceModelDestroyed();
+    // same as in _q_sourceReset()
+    d->invalidatePersistentIndexes();
+    d->_q_clearMapping();
+
     QAbstractProxyModel::setSourceModel(sourceModel);
 
     connect(d->model, SIGNAL(dataChanged(QModelIndex,QModelIndex,QVector<int>)),
diff --git a/tests/auto/corelib/itemmodels/qsortfilterproxymodel/tst_qsortfilterproxymodel.cpp b/tests/auto/corelib/itemmodels/qsortfilterproxymodel/tst_qsortfilterproxymodel.cpp
index 1acedf4271..296442b0c7 100644
--- a/tests/auto/corelib/itemmodels/qsortfilterproxymodel/tst_qsortfilterproxymodel.cpp
+++ b/tests/auto/corelib/itemmodels/qsortfilterproxymodel/tst_qsortfilterproxymodel.cpp
@@ -4516,15 +4516,25 @@ void tst_QSortFilterProxyModel::checkSetNewModel()
     QTreeView tv;
     StepTreeModel model1;
     model1.setDepth(4);
-    StepTreeModel model2;
-    model2.setDepth(4);
 
     QSortFilterProxyModel proxy;
     proxy.setSourceModel(&model1);
     tv.setModel(&proxy);
     tv.show();
-    tv.expandAll(); // create persistent indexes
-    proxy.setSourceModel(&model2);
+    QVERIFY(QTest::qWaitForWindowExposed(&tv));
+    tv.expandAll();
+    {
+        StepTreeModel model2;
+        model2.setDepth(4);
+        proxy.setSourceModel(&model2);
+        tv.expandAll();
+        proxy.setSourceModel(&model1);
+        tv.expandAll();
+        // the destruction of model2 here caused a proxy model reset due to
+        // missing disconnect in setSourceModel()
+    }
+    // handle repaint events, will assert when qsortfilterproxymodel is in wrong state
+    QCoreApplication::processEvents();
 }
 
 QTEST_MAIN(tst_QSortFilterProxyModel)