From 14235ada48d5f3015571102549d56c8cfbcdcccb Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@kdab.com>
Date: Thu, 9 Jul 2015 21:40:58 +0200
Subject: [PATCH] QGraphicsItem: don't hold ExtraStruct in a QList

ExtraStruct is larger than a void*, so holding it in QList
is needlessly inefficient. Worse, the code could come to depend
on the fragile property of (inefficient) QLists that references
to elements therein never are invalidated.

Fix by marking it movable, and holding in a QVector instead.

Change-Id: I02f2089859c2deccf0e6c451bf80da07893cc3f0
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
---
 src/widgets/graphicsview/qgraphicsitem_p.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/widgets/graphicsview/qgraphicsitem_p.h b/src/widgets/graphicsview/qgraphicsitem_p.h
index bf788d2c39..fe4bac12bc 100644
--- a/src/widgets/graphicsview/qgraphicsitem_p.h
+++ b/src/widgets/graphicsview/qgraphicsitem_p.h
@@ -353,6 +353,7 @@ public:
     }
 
     struct ExtraStruct {
+        ExtraStruct() {} // for QVector, don't use
         ExtraStruct(Extra type, QVariant value)
             : type(type), value(value)
         { }
@@ -364,7 +365,7 @@ public:
         { return type < extra; }
     };
 
-    QList<ExtraStruct> extras;
+    QVector<ExtraStruct> extras;
 
     QGraphicsItemCache *maybeExtraItemCache() const;
     QGraphicsItemCache *extraItemCache() const;
@@ -584,6 +585,7 @@ public:
     int globalStackingOrder;
     QGraphicsItem *q_ptr;
 };
+Q_DECLARE_TYPEINFO(QGraphicsItemPrivate::ExtraStruct, Q_MOVABLE_TYPE);
 
 struct QGraphicsItemPrivate::TransformData
 {