TabBar: fix binding loop on currentIndex

TabBar is a container of exclusive items aka TabButtons. In this case
we let ExclusiveGroup manage the currently checked item, and just sync
the current index when appropriate. In the case of a SwipeView, which
contains arbitrary non-checkable items, we track the current index of
the content item. However, we should avoid doing both at the same time,
because it leads to a race between content item's current index and
exclusive group's current item.

Change-Id: Ib2d4dfe0d22d883be49b03a3b2311bdea7d937d9
Task-number: QTBUG-48993
Reviewed-by: Mitch Curtis <mitch.curtis@theqtcompany.com>

1 files changed, 10 insertions, 6 deletions

diff --git a/src/templates/qquickcontainer.cpp b/src/templates/qquickcontainer.cpp
index 5bd3e8f3..ef08161f 100644
--- a/src/templates/qquickcontainer.cpp
+++ b/src/templates/qquickcontainer.cpp
@@ -515,17 +515,21 @@ void QQuickContainer::contentItemChange(QQuickItem *newItem, QQuickItem *oldItem
     if (oldItem) {
         QQuickItemPrivate::get(oldItem)->removeItemChangeListener(d, QQuickItemPrivate::Children);
 
-        int signalIndex = oldItem->metaObject()->indexOfSignal("currentIndexChanged()");
-        if (signalIndex != -1)
-            QMetaObject::disconnect(oldItem, signalIndex, this, slotIndex);
+        if (!d->exclusiveGroup) {
+            int signalIndex = oldItem->metaObject()->indexOfSignal("currentIndexChanged()");
+            if (signalIndex != -1)
+                QMetaObject::disconnect(oldItem, signalIndex, this, slotIndex);
+        }
     }
 
     if (newItem) {
         QQuickItemPrivate::get(newItem)->addItemChangeListener(d, QQuickItemPrivate::Children);
 
-        int signalIndex = newItem->metaObject()->indexOfSignal("currentIndexChanged()");
-        if (signalIndex != -1)
-            QMetaObject::connect(newItem, signalIndex, this, slotIndex);
+        if (!d->exclusiveGroup) {
+            int signalIndex = newItem->metaObject()->indexOfSignal("currentIndexChanged()");
+            if (signalIndex != -1)
+                QMetaObject::connect(newItem, signalIndex, this, slotIndex);
+        }
     }
 }