Fix tree recursion in QAbstractItemModel::match()

Recurse down the sibling at column 0 of the index instead down the
index.

Change-Id: Ie78d8b28eab7438ca3f83ee0df177115ca82806e
Fixes: QTBUG-73864
Reviewed-by: David Faure <david.faure@kdab.com>

src/corelib/itemmodels/qabstractitemmodel.cpp

@@ -2360,6 +2360,7 @@ QModelIndexList QAbstractItemModel::match(const QModelIndex &start, int role,
     bool wrap = flags & Qt::MatchWrap;
     bool allHits = (hits == -1);
     QString text; // only convert to a string if it is needed
+    const int column = start.column();
     QModelIndex p = parent(start);
     int from = start.row();
     int to = rowCount(p);
@@ -2367,7 +2368,7 @@ QModelIndexList QAbstractItemModel::match(const QModelIndex &start, int role,
     // iterates twice if wrapping
     for (int i = 0; (wrap && i < 2) || (!wrap && i < 1); ++i) {
         for (int r = from; (r < to) && (allHits || result.count() < hits); ++r) {
-            QModelIndex idx = index(r, start.column(), p);
+            QModelIndex idx = index(r, column, p);
             if (!idx.isValid())
                  continue;
             QVariant v = data(idx, role);
@@ -2406,12 +2407,15 @@ QModelIndexList QAbstractItemModel::match(const QModelIndex &start, int role,
                         result.append(idx);
                 }
             }
-            if (recurse && hasChildren(idx)) { // search the hierarchy
-                result += match(index(0, idx.column(), idx), role,
+            if (recurse) {
+                const auto parent = column != 0 ? idx.sibling(idx.row(), 0) : idx;
+                if (hasChildren(parent)) { // search the hierarchy
+                    result += match(index(0, column, parent), role,
                                     (text.isEmpty() ? value : text),
                                     (allHits ? -1 : hits - result.count()), flags);
                 }
             }
+        }
         // prepare for the next iteration
         from = 0;
         to = start.row();

tests/auto/corelib/itemmodels/qsortfilterproxymodel_common/tst_qsortfilterproxymodel.cpp

@@ -2363,6 +2363,45 @@ void tst_QSortFilterProxyModel::match()
         QCOMPARE(indexes.at(i).row(), expectedProxyItems.at(i));
 }
 
+QList<QStandardItem *> createStandardItemList(const QString &prefix, int n)
+{
+    QList<QStandardItem *> result;
+    for (int i = 0; i < n; ++i)
+        result.append(new QStandardItem(prefix + QString::number(i)));
+    return result;
+}
+
+// QTBUG-73864, recursive search in a tree model.
+
+void tst_QSortFilterProxyModel::matchTree()
+{
+    QStandardItemModel model(0, 2);
+    // Header00 Header01
+    // Header10 Header11
+    //   Item00 Item01
+    //   Item10 Item11
+    model.appendRow(createStandardItemList(QLatin1String("Header0"), 2));
+    auto headerRow = createStandardItemList(QLatin1String("Header1"), 2);
+    model.appendRow(headerRow);
+    headerRow.first()->appendRow(createStandardItemList(QLatin1String("Item0"), 2));
+    headerRow.first()->appendRow(createStandardItemList(QLatin1String("Item1"), 2));
+
+    auto item11 = model.match(model.index(1, 1), Qt::DisplayRole, QLatin1String("Item11"), 20,
+                              Qt::MatchRecursive).value(0);
+    QVERIFY(item11.isValid());
+    QCOMPARE(item11.data().toString(), QLatin1String("Item11"));
+
+    // Repeat in proxy model
+    QSortFilterProxyModel proxy;
+    proxy.setSourceModel(&model);
+    auto proxyItem11 = proxy.match(proxy.index(1, 1), Qt::DisplayRole, QLatin1String("Item11"), 20,
+                              Qt::MatchRecursive).value(0);
+    QVERIFY(proxyItem11.isValid());
+    QCOMPARE(proxyItem11.data().toString(), QLatin1String("Item11"));
+
+    QCOMPARE(proxy.mapToSource(proxyItem11).internalId(), item11.internalId());
+}
+
 void tst_QSortFilterProxyModel::insertIntoChildrenlessItem()
 {
     QStandardItemModel model;

tests/auto/corelib/itemmodels/qsortfilterproxymodel_common/tst_qsortfilterproxymodel.h

@@ -109,6 +109,7 @@ private slots:
     void selectionFilteredOut();
     void match_data();
     void match();
+    void matchTree();
     void insertIntoChildrenlessItem();
     void invalidateMappedChildren();
     void insertRowIntoFilteredParent();