From 931f9c23ee884fe929aed50404a29776826d8bd4 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@kdab.com>
Date: Sat, 16 Aug 2014 20:28:10 +0200
Subject: [PATCH] QMacStyle: replace a QSet<QPointer> with QVector<QPointer>

Holding a mutable item in a QSet violates QSet invariants, namely that in
bucket N, all items have hash % size == N. If a value gets reset to
nullptr by external means, that invariant no longer holds. The code works
by pure luck.

Replace the set with a vector, which doesn't care whether elements change
under the hood, and will also outperform the typical QSet use due to
better locality of reference.

Change-Id: Ied7940e82525fd0da9f74dfb0bc36a320b45d172
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
---
 src/widgets/styles/qmacstyle_mac.mm    | 11 +++--------
 src/widgets/styles/qmacstyle_mac_p_p.h |  4 ++--
 2 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/src/widgets/styles/qmacstyle_mac.mm b/src/widgets/styles/qmacstyle_mac.mm
index 50c8fd7ed8..cf10fe7acd 100644
--- a/src/widgets/styles/qmacstyle_mac.mm
+++ b/src/widgets/styles/qmacstyle_mac.mm
@@ -114,7 +114,7 @@ QT_NAMESPACE_ALIAS_OBJC_CLASS(NotificationReceiver);
 {
     Q_UNUSED(notification);
     QEvent event(QEvent::StyleChange);
-    QMutableSetIterator<QPointer<QObject> > it(QMacStylePrivate::scrollBars);
+    QMutableVectorIterator<QPointer<QObject> > it(QMacStylePrivate::scrollBars);
     while (it.hasNext()) {
         if (!it.next())
             it.remove();
@@ -138,12 +138,7 @@ const int QMacStylePrivate::BevelButtonW = 50;
 const int QMacStylePrivate::BevelButtonH = 22;
 const int QMacStylePrivate::PushButtonContentPadding = 6;
 
-QSet<QPointer<QObject> > QMacStylePrivate::scrollBars;
-
-static uint qHash(const QPointer<QObject> &ptr)
-{
-    return qHash(ptr.data());
-}
+QVector<QPointer<QObject> > QMacStylePrivate::scrollBars;
 
 // Title bar gradient colors for Lion were determined by inspecting PSDs exported
 // using CoreUI's CoreThemeDocument; there is no public API to retrieve them
@@ -5367,7 +5362,7 @@ void QMacStyle::drawComplexControl(ComplexControl cc, const QStyleOptionComplex
             // there is not enough space for them.
             if (cc == CC_ScrollBar) {
                 if (opt && opt->styleObject && !QMacStylePrivate::scrollBars.contains(opt->styleObject))
-                    QMacStylePrivate::scrollBars.insert(QPointer<QObject>(opt->styleObject));
+                    QMacStylePrivate::scrollBars.append(QPointer<QObject>(opt->styleObject));
                 const int scrollBarLength = (slider->orientation == Qt::Horizontal)
                     ? slider->rect.width() : slider->rect.height();
                 const QMacStyle::WidgetSizePolicy sizePolicy = widgetSizePolicy(widget, opt);
diff --git a/src/widgets/styles/qmacstyle_mac_p_p.h b/src/widgets/styles/qmacstyle_mac_p_p.h
index b09e81d595..33818568ec 100644
--- a/src/widgets/styles/qmacstyle_mac_p_p.h
+++ b/src/widgets/styles/qmacstyle_mac_p_p.h
@@ -86,7 +86,7 @@
 #include <qdatetimeedit.h>
 #include <qmath.h>
 #include <qpair.h>
-#include <qset.h>
+#include <qvector.h>
 #include <QtWidgets/qgraphicsproxywidget.h>
 #include <QtWidgets/qgraphicsview.h>
 
@@ -213,7 +213,7 @@ public:
     mutable QPointer<QObject> pressedButton;
     mutable QPointer<QObject> defaultButton;
     mutable QPointer<QObject> autoDefaultButton;
-    static  QSet<QPointer<QObject> > scrollBars;
+    static  QVector<QPointer<QObject> > scrollBars;
 
     struct ButtonState {
         int frame;