From 564086b366427da27eb1573e82fda7ab62dc4a17 Mon Sep 17 00:00:00 2001
From: "Bradley T. Hughes" <bradley.hughes@nokia.com>
Date: Fri, 9 Sep 2011 11:08:25 +0200
Subject: Make QMapData::shared_null const

Similar to QVector, QByteArray and QString, keep the shared_null in
shareable memory and never modify it.

Change-Id: I062825684b79f2b01ec7ce65e0cf74f417b760b8
Reviewed-on: http://codereview.qt-project.org/4530
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>
---
 src/corelib/tools/qmap.cpp | 8 ++++----
 src/corelib/tools/qmap.h   | 8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/corelib/tools/qmap.cpp b/src/corelib/tools/qmap.cpp
index aecc73c8dd..bd7c76c37a 100644
--- a/src/corelib/tools/qmap.cpp
+++ b/src/corelib/tools/qmap.cpp
@@ -50,10 +50,10 @@
 
 QT_BEGIN_NAMESPACE
 
-QMapData QMapData::shared_null = {
-    &shared_null,
-    { &shared_null, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
-    Q_BASIC_ATOMIC_INITIALIZER(1), 0, 0, 0, false, true, false, 0
+const QMapData QMapData::shared_null = {
+    const_cast<QMapData *>(&shared_null),
+    { const_cast<QMapData *>(&shared_null), 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
+    Q_REFCOUNT_INITIALIZER(-1), 0, 0, 0, false, true, false, 0
 };
 
 QMapData *QMapData::createData()
diff --git a/src/corelib/tools/qmap.h b/src/corelib/tools/qmap.h
index 771959a3bf..ff181d5071 100644
--- a/src/corelib/tools/qmap.h
+++ b/src/corelib/tools/qmap.h
@@ -42,9 +42,9 @@
 #ifndef QMAP_H
 #define QMAP_H
 
-#include <QtCore/qatomic.h>
 #include <QtCore/qiterator.h>
 #include <QtCore/qlist.h>
+#include <QtCore/qrefcount.h>
 
 #ifndef QT_NO_STL
 #include <map>
@@ -68,7 +68,7 @@ struct Q_CORE_EXPORT QMapData
 
     QMapData *backward;
     QMapData *forward[QMapData::LastLevel + 1];
-    QBasicAtomicInt ref;
+    QtPrivate::RefCount ref;
     int topLevel;
     int size;
     uint randomBits;
@@ -88,7 +88,7 @@ struct Q_CORE_EXPORT QMapData
     void dump();
 #endif
 
-    static QMapData shared_null;
+    static const QMapData shared_null;
 };
 
 
@@ -179,7 +179,7 @@ class QMap
     }
 
 public:
-    inline QMap() : d(&QMapData::shared_null) { d->ref.ref(); }
+    inline QMap() : d(const_cast<QMapData *>(&QMapData::shared_null)) { }
     inline QMap(const QMap<Key, T> &other) : d(other.d)
     { d->ref.ref(); if (!d->sharable) detach(); }
     inline ~QMap() { if (!d) return; if (!d->ref.deref()) freeData(d); }
-- 
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