QHeaderView: fix visual/logical index corruption when restoring statev5.9.0-rc2v5.9.0

This is a followup to 77a8e90cddcfa1c34518ef846a4838874a7bc0c7 which
didn't handle the case where no columns had been moved.
visualIndices and logicalIndices are empty until initializeIndexMapping()
is called, in which case appending is wrong.

As a result, visualIndex(i) would return -1 for the values over
those added by read(), and an assert would happen at painting time.

The fix is to leave visualIndices and logicalIndices empty if
they are empty already, leaving it to initializeIndexMapping()
to fill them later if necessary (e.g. when moving a column).

Task-number: QTBUG-60837
Change-Id: Ia7e4b9d3122647984acd434dfaa0400df319d065
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Thorbjørn Lund Martsum <tmartsum@gmail.com>

1 files changed, 50 insertions, 0 deletions

diff --git a/tests/auto/widgets/itemviews/qheaderview/tst_qheaderview.cpp b/tests/auto/widgets/itemviews/qheaderview/tst_qheaderview.cpp
index 7bfec2831d..b13e7b2f33 100644
--- a/tests/auto/widgets/itemviews/qheaderview/tst_qheaderview.cpp
+++ b/tests/auto/widgets/itemviews/qheaderview/tst_qheaderview.cpp
@@ -171,6 +171,7 @@ private slots:
     void saveRestore();
     void restoreQt4State();
     void restoreToMoreColumns();
+    void restoreToMoreColumnsNoMovedColumns();
     void restoreBeforeSetModel();
     void defaultSectionSizeTest();
     void defaultSectionSizeTestStyles();
@@ -1690,6 +1691,55 @@ void tst_QHeaderView::restoreToMoreColumns()
     QCOMPARE(h4.hiddenSectionCount(), 1);
     QCOMPARE(h4.sortIndicatorSection(), 2);
     QCOMPARE(h4.sortIndicatorOrder(), Qt::DescendingOrder);
+    QCOMPARE(h4.logicalIndex(0), 2);
+    QCOMPARE(h4.logicalIndex(1), 1);
+    QCOMPARE(h4.logicalIndex(2), 0);
+    QCOMPARE(h4.visualIndex(0), 2);
+    QCOMPARE(h4.visualIndex(1), 1);
+    QCOMPARE(h4.visualIndex(2), 0);
+
+    // Repainting shouldn't crash
+    h4.show();
+    QVERIFY(QTest::qWaitForWindowExposed(&h4));
+}
+
+void tst_QHeaderView::restoreToMoreColumnsNoMovedColumns()
+{
+    // Given a model with 2 columns, for saving state
+    QHeaderView h1(Qt::Horizontal);
+    QStandardItemModel model1(1, 2);
+    h1.setModel(&model1);
+    QCOMPARE(h1.visualIndex(0), 0);
+    QCOMPARE(h1.visualIndex(1), 1);
+    QCOMPARE(h1.logicalIndex(0), 0);
+    QCOMPARE(h1.logicalIndex(1), 1);
+    const QByteArray savedState = h1.saveState();
+
+    // And a model with 3 columns, to apply that state upon
+    QHeaderView h2(Qt::Horizontal);
+    QStandardItemModel model2(1, 3);
+    h2.setModel(&model2);
+    QCOMPARE(h2.visualIndex(0), 0);
+    QCOMPARE(h2.visualIndex(1), 1);
+    QCOMPARE(h2.visualIndex(2), 2);
+    QCOMPARE(h2.logicalIndex(0), 0);
+    QCOMPARE(h2.logicalIndex(1), 1);
+    QCOMPARE(h2.logicalIndex(2), 2);
+
+    // When calling restoreState()
+    QVERIFY(h2.restoreState(savedState));
+
+    // Then the index mapping should still be as default
+    QCOMPARE(h2.visualIndex(0), 0);
+    QCOMPARE(h2.visualIndex(1), 1);
+    QCOMPARE(h2.visualIndex(2), 2);
+    QCOMPARE(h2.logicalIndex(0), 0);
+    QCOMPARE(h2.logicalIndex(1), 1);
+    QCOMPARE(h2.logicalIndex(2), 2);
+
+    // And repainting shouldn't crash
+    h2.show();
+    QVERIFY(QTest::qWaitForWindowExposed(&h2));
 }
 
 void tst_QHeaderView::restoreBeforeSetModel()