Protect tab focus chain from infinite loops when item is invisible

Make sure to start the search for a potential focus item on an item that
will be visited again later, otherwise we'll loop for ever.

Fixes: QTBUG-68271
Change-Id: Icb330e4e726132511810027a33b9fb346c7fa131
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@qt.io>

1 files changed, 17 insertions, 0 deletions

diff --git a/tests/auto/quick/qquickitem2/tst_qquickitem.cpp b/tests/auto/quick/qquickitem2/tst_qquickitem.cpp
index f0f5873ace..7107f4d995 100644
--- a/tests/auto/quick/qquickitem2/tst_qquickitem.cpp
+++ b/tests/auto/quick/qquickitem2/tst_qquickitem.cpp
@@ -64,6 +64,7 @@ private slots:
     void activeFocusOnTab8();
     void activeFocusOnTab9();
     void activeFocusOnTab10();
+    void activeFocusOnTab_infiniteLoop();
 
     void nextItemInFocusChain();
     void nextItemInFocusChain2();
@@ -1023,6 +1024,22 @@ void tst_QQuickItem::activeFocusOnTab10()
     delete window;
 }
 
+void tst_QQuickItem::activeFocusOnTab_infiniteLoop()
+{
+    // see QTBUG-68271
+    // create a window where the currently focused item is not visible
+    QScopedPointer<QQuickView>window(new QQuickView());
+    window->setSource(testFileUrl("activeFocusOnTab_infiniteLoop.qml"));
+    window->show();
+    auto *hiddenChild = findItem<QQuickItem>(window->rootObject(), "hiddenChild");
+    QVERIFY(hiddenChild);
+
+    // move the focus - this used to result in an infinite loop
+    auto *item = hiddenChild->nextItemInFocusChain();
+    // focus is moved to the root object since there is no other candidate
+    QCOMPARE(item, window->rootObject());
+}
+
 void tst_QQuickItem::nextItemInFocusChain()
 {
     if (!qt_tab_all_widgets())