Fix z-value of QGraphicsItems being ignored during draw

In QGraphicsScene's function draw, don't copy the children into a
const copy (to prevent detaching in the loops), as they might get
sorted. Instead, use a const reference.

Amends e349f787d595aa343ca86af94159b6730d55b8d5, which introduced
the bug by making a copy of the unsorted list.

Fixes: QTBUG-81316
Pick-to: 6.0 6.1
Change-Id: Iab9b87e75178a883806088a9db234c7a2aaa9301
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/widgets/graphicsview/qgraphicsscene.cpp b/src/widgets/graphicsview/qgraphicsscene.cpp
index 2e65effb1a..dd54a4bffa 100644
--- a/src/widgets/graphicsview/qgraphicsscene.cpp
+++ b/src/widgets/graphicsview/qgraphicsscene.cpp
@@ -4821,7 +4821,7 @@ void QGraphicsScenePrivate::draw(QGraphicsItem *item, QPainter *painter, const Q
                                  qreal opacity, const QTransform *effectTransform,
                                  bool wasDirtyParentSceneTransform, bool drawItem)
 {
-    const auto children = item->d_ptr->children;
+    const auto &children = item->d_ptr->children;
 
     const bool itemIsFullyTransparent = QGraphicsItemPrivate::isOpacityNull(opacity);
     const bool itemClipsChildrenToShape = (item->d_ptr->flags & QGraphicsItem::ItemClipsChildrenToShape);