Merge remote-tracking branch 'origin/5.5' into dev

Change-Id: I9d10911c51700965f2cf0e3173b88fd9116bd3ee

18 files changed, 244 insertions, 69 deletions

diff --git a/src/corelib/arch/qatomic_cxx11.h b/src/corelib/arch/qatomic_cxx11.h
index a58c8ab72e..09e900f4ea 100644
--- a/src/corelib/arch/qatomic_cxx11.h
+++ b/src/corelib/arch/qatomic_cxx11.h
@@ -230,6 +230,102 @@ template <typename X> struct QAtomicOps
     {
         return _q_value.fetch_add(valueToAdd, std::memory_order_acq_rel);
     }
+
+    template <typename T> static inline
+    T fetchAndSubRelaxed(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_sub(valueToAdd, std::memory_order_relaxed);
+    }
+
+    template <typename T> static inline
+    T fetchAndSubAcquire(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_sub(valueToAdd, std::memory_order_acquire);
+    }
+
+    template <typename T> static inline
+    T fetchAndSubRelease(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_sub(valueToAdd, std::memory_order_release);
+    }
+
+    template <typename T> static inline
+    T fetchAndSubOrdered(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_sub(valueToAdd, std::memory_order_acq_rel);
+    }
+
+    template <typename T> static inline
+    T fetchAndAndRelaxed(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_and(valueToAdd, std::memory_order_relaxed);
+    }
+
+    template <typename T> static inline
+    T fetchAndAndAcquire(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_and(valueToAdd, std::memory_order_acquire);
+    }
+
+    template <typename T> static inline
+    T fetchAndAndRelease(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_and(valueToAdd, std::memory_order_release);
+    }
+
+    template <typename T> static inline
+    T fetchAndAndOrdered(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_and(valueToAdd, std::memory_order_acq_rel);
+    }
+
+    template <typename T> static inline
+    T fetchAndOrRelaxed(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_or(valueToAdd, std::memory_order_relaxed);
+    }
+
+    template <typename T> static inline
+    T fetchAndOrAcquire(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_or(valueToAdd, std::memory_order_acquire);
+    }
+
+    template <typename T> static inline
+    T fetchAndOrRelease(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_or(valueToAdd, std::memory_order_release);
+    }
+
+    template <typename T> static inline
+    T fetchAndOrOrdered(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_or(valueToAdd, std::memory_order_acq_rel);
+    }
+
+    template <typename T> static inline
+    T fetchAndXorRelaxed(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_xor(valueToAdd, std::memory_order_relaxed);
+    }
+
+    template <typename T> static inline
+    T fetchAndXorAcquire(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_xor(valueToAdd, std::memory_order_acquire);
+    }
+
+    template <typename T> static inline
+    T fetchAndXorRelease(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_xor(valueToAdd, std::memory_order_release);
+    }
+
+    template <typename T> static inline
+    T fetchAndXorOrdered(std::atomic<T> &_q_value, typename QAtomicAdditiveType<T>::AdditiveT valueToAdd) Q_DECL_NOTHROW
+    {
+        return _q_value.fetch_xor(valueToAdd, std::memory_order_acq_rel);
+    }
 };
 
 #ifdef ATOMIC_VAR_INIT
diff --git a/src/corelib/global/qglobal.h b/src/corelib/global/qglobal.h
index 2d3a78db01..6aa3eb305b 100644
--- a/src/corelib/global/qglobal.h
+++ b/src/corelib/global/qglobal.h
@@ -585,6 +585,10 @@ class QDataStream;
 #  define QT_NO_SOCKS5
 #endif
 
+#if defined(Q_OS_IOS)
+#  define QT_NO_PROCESS
+#endif
+
 inline void qt_noop(void) {}
 
 /* These wrap try/catch so we can switch off exceptions later.
@@ -660,7 +664,7 @@ Q_CORE_EXPORT void qt_assert(const char *assertion, const char *file, int line)
 
 #if !defined(Q_ASSERT)
 #  if defined(QT_NO_DEBUG) && !defined(QT_FORCE_ASSERTS)
-#    define Q_ASSERT(cond) do { } while (false && (cond))
+#    define Q_ASSERT(cond) do { } while ((false) && (cond))
 #  else
 #    define Q_ASSERT(cond) ((!(cond)) ? qt_assert(#cond,__FILE__,__LINE__) : qt_noop())
 #  endif
diff --git a/src/corelib/global/qnamespace.h b/src/corelib/global/qnamespace.h
index e115cedc51..420b8b0430 100644
--- a/src/corelib/global/qnamespace.h
+++ b/src/corelib/global/qnamespace.h
@@ -1663,6 +1663,7 @@ public:
     QT_Q_ENUM(ItemSelectionOperation)
     QT_Q_FLAG(ItemFlags)
     QT_Q_ENUM(CheckState)
+    QT_Q_ENUM(ItemDataRole)
     QT_Q_ENUM(SortOrder)
     QT_Q_ENUM(CaseSensitivity)
     QT_Q_FLAG(MatchFlags)
diff --git a/src/corelib/io/qlockfile_unix.cpp b/src/corelib/io/qlockfile_unix.cpp
index 5719d899a0..1c8da607a7 100644
--- a/src/corelib/io/qlockfile_unix.cpp
+++ b/src/corelib/io/qlockfile_unix.cpp
@@ -157,13 +157,17 @@ QLockFile::LockError QLockFilePrivate::tryLock_sys()
     if (!setNativeLocks(fd))
         qWarning() << "setNativeLocks failed:" << strerror(errno);
 
+    if (qt_write_loop(fd, fileData.constData(), fileData.size()) < fileData.size()) {
+        close(fd);
+        if (!QFile::remove(fileName))
+            qWarning("QLockFile: Could not remove our own lock file %s.", qPrintable(fileName));
+        return QLockFile::UnknownError; // partition full
+    }
+
     // We hold the lock, continue.
     fileHandle = fd;
 
-    QLockFile::LockError error = QLockFile::NoError;
-    if (qt_write_loop(fd, fileData.constData(), fileData.size()) < fileData.size())
-        error = QLockFile::UnknownError; // partition full
-    return error;
+    return QLockFile::NoError;
 }
 
 bool QLockFilePrivate::removeStaleLock()
diff --git a/src/corelib/itemmodels/qabstractitemmodel.h b/src/corelib/itemmodels/qabstractitemmodel.h
index 7789c0d483..1c2ff9f190 100644
--- a/src/corelib/itemmodels/qabstractitemmodel.h
+++ b/src/corelib/itemmodels/qabstractitemmodel.h
@@ -164,20 +164,20 @@ public:
     explicit QAbstractItemModel(QObject *parent = 0);
     virtual ~QAbstractItemModel();
 
-    bool hasIndex(int row, int column, const QModelIndex &parent = QModelIndex()) const;
-    virtual QModelIndex index(int row, int column,
+    Q_INVOKABLE bool hasIndex(int row, int column, const QModelIndex &parent = QModelIndex()) const;
+    Q_INVOKABLE virtual QModelIndex index(int row, int column,
                               const QModelIndex &parent = QModelIndex()) const = 0;
-    virtual QModelIndex parent(const QModelIndex &child) const = 0;
+    Q_INVOKABLE virtual QModelIndex parent(const QModelIndex &child) const = 0;
 
-    virtual QModelIndex sibling(int row, int column, const QModelIndex &idx) const;
-    virtual int rowCount(const QModelIndex &parent = QModelIndex()) const = 0;
-    virtual int columnCount(const QModelIndex &parent = QModelIndex()) const = 0;
-    virtual bool hasChildren(const QModelIndex &parent = QModelIndex()) const;
+    Q_INVOKABLE virtual QModelIndex sibling(int row, int column, const QModelIndex &idx) const;
+    Q_INVOKABLE virtual int rowCount(const QModelIndex &parent = QModelIndex()) const = 0;
+    Q_INVOKABLE virtual int columnCount(const QModelIndex &parent = QModelIndex()) const = 0;
+    Q_INVOKABLE virtual bool hasChildren(const QModelIndex &parent = QModelIndex()) const;
 
-    virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const = 0;
-    virtual bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole);
+    Q_INVOKABLE virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const = 0;
+    Q_INVOKABLE virtual bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole);
 
-    virtual QVariant headerData(int section, Qt::Orientation orientation,
+    Q_INVOKABLE virtual QVariant headerData(int section, Qt::Orientation orientation,
                                 int role = Qt::DisplayRole) const;
     virtual bool setHeaderData(int section, Qt::Orientation orientation, const QVariant &value,
                                int role = Qt::EditRole);
@@ -217,9 +217,9 @@ public:
     inline bool moveColumn(const QModelIndex &sourceParent, int sourceColumn,
                            const QModelIndex &destinationParent, int destinationChild);
 
-    virtual void fetchMore(const QModelIndex &parent);
-    virtual bool canFetchMore(const QModelIndex &parent) const;
-    virtual Qt::ItemFlags flags(const QModelIndex &index) const;
+    Q_INVOKABLE virtual void fetchMore(const QModelIndex &parent);
+    Q_INVOKABLE virtual bool canFetchMore(const QModelIndex &parent) const;
+    Q_INVOKABLE virtual Qt::ItemFlags flags(const QModelIndex &index) const;
     virtual void sort(int column, Qt::SortOrder order = Qt::AscendingOrder);
     virtual QModelIndex buddy(const QModelIndex &index) const;
     virtual QModelIndexList match(const QModelIndex &start, int role,
@@ -484,6 +484,5 @@ inline uint qHash(const QModelIndex &index) Q_DECL_NOTHROW
 QT_END_NAMESPACE
 
 Q_DECLARE_METATYPE(QModelIndexList)
-Q_DECLARE_METATYPE(QPersistentModelIndex)
 
 #endif // QABSTRACTITEMMODEL_H
diff --git a/src/corelib/itemmodels/qitemselectionmodel.h b/src/corelib/itemmodels/qitemselectionmodel.h
index fe0bd459cd..09fab78214 100644
--- a/src/corelib/itemmodels/qitemselectionmodel.h
+++ b/src/corelib/itemmodels/qitemselectionmodel.h
@@ -146,6 +146,7 @@ class Q_CORE_EXPORT QItemSelectionModel : public QObject
     Q_PROPERTY(QAbstractItemModel *model READ model WRITE setModel NOTIFY modelChanged)
     Q_PROPERTY(bool hasSelection READ hasSelection NOTIFY selectionChanged STORED false DESIGNABLE false)
     Q_PROPERTY(QModelIndex currentIndex READ currentIndex NOTIFY currentChanged STORED false DESIGNABLE false)
+    Q_PROPERTY(QItemSelection selection READ selection NOTIFY selectionChanged STORED false DESIGNABLE false)
 
     Q_DECLARE_PRIVATE(QItemSelectionModel)
 
@@ -186,7 +187,7 @@ public:
     Q_INVOKABLE QModelIndexList selectedIndexes() const;
     Q_INVOKABLE QModelIndexList selectedRows(int column = 0) const;
     Q_INVOKABLE QModelIndexList selectedColumns(int row = 0) const;
-    Q_INVOKABLE const QItemSelection selection() const;
+    const QItemSelection selection() const;
 
     // ### Qt 6: Merge these two as "QAbstractItemModel *model() const"
     const QAbstractItemModel *model() const;
diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index 18a379f8b9..0bde57c8b3 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -368,7 +368,9 @@ struct QCoreApplicationData {
     }
 #endif
 
-    QString orgName, orgDomain, application;
+    QString orgName, orgDomain;
+    QString application; // application name, initially from argv[0], can then be modified.
+    QString applicationNameCompat; // for QDesktopServices. Only set explicitly.
     QString applicationVersion;
 
 #ifndef QT_NO_LIBRARY
@@ -750,6 +752,9 @@ void QCoreApplication::init()
     Q_ASSERT_X(!self, "QCoreApplication", "there should be only one application object");
     QCoreApplication::self = this;
 
+    // Store app name (so it's still available after QCoreApplication is destroyed)
+    coreappdata()->application = d_func()->appName();
+
     QLoggingRegistry::instance()->init();
 
 #ifndef QT_NO_QOBJECT
@@ -2345,9 +2350,13 @@ QString QCoreApplication::organizationDomain()
 */
 void QCoreApplication::setApplicationName(const QString &application)
 {
-    if (coreappdata()->application == application)
+    QString newAppName = application;
+    if (newAppName.isEmpty() && QCoreApplication::self)
+        newAppName = QCoreApplication::self->d_func()->appName();
+    if (coreappdata()->application == newAppName)
         return;
-    coreappdata()->application = application;
+    coreappdata()->application = newAppName;
+    coreappdata()->applicationNameCompat = newAppName;
 #ifndef QT_NO_QOBJECT
     if (QCoreApplication::self)
         emit QCoreApplication::self->applicationNameChanged();
@@ -2359,16 +2368,13 @@ QString QCoreApplication::applicationName()
 #ifdef Q_OS_BLACKBERRY
     coreappdata()->loadManifest();
 #endif
-    QString appname = coreappdata() ? coreappdata()->application : QString();
-    if (appname.isEmpty() && QCoreApplication::self)
-        appname = QCoreApplication::self->d_func()->appName();
-    return appname;
+    return coreappdata() ? coreappdata()->application : QString();
 }
 
 // Exported for QDesktopServices (Qt4 behavior compatibility)
 Q_CORE_EXPORT QString qt_applicationName_noFallback()
 {
-    return coreappdata()->application;
+    return coreappdata()->applicationNameCompat;
 }
 
 /*!
diff --git a/src/corelib/kernel/qmetatype.cpp b/src/corelib/kernel/qmetatype.cpp
index 305e998818..d4a69ee4b9 100644
--- a/src/corelib/kernel/qmetatype.cpp
+++ b/src/corelib/kernel/qmetatype.cpp
@@ -277,6 +277,7 @@ struct DefinedTypesFilter {
     \value QJsonArray QJsonArray
     \value QJsonDocument QJsonDocument
     \value QModelIndex QModelIndex
+    \value QPersistentModelIndex QPersistentModelIndex (since 5.5)
     \value QUuid QUuid
     \value QByteArrayList QByteArrayList
 
@@ -1209,6 +1210,7 @@ bool QMetaType::save(QDataStream &stream, int type, const void *data)
     case QMetaType::VoidStar:
     case QMetaType::QObjectStar:
     case QMetaType::QModelIndex:
+    case QMetaType::QPersistentModelIndex:
     case QMetaType::QJsonValue:
     case QMetaType::QJsonObject:
     case QMetaType::QJsonArray:
@@ -1429,6 +1431,7 @@ bool QMetaType::load(QDataStream &stream, int type, void *data)
     case QMetaType::VoidStar:
     case QMetaType::QObjectStar:
     case QMetaType::QModelIndex:
+    case QMetaType::QPersistentModelIndex:
     case QMetaType::QJsonValue:
     case QMetaType::QJsonObject:
     case QMetaType::QJsonArray:
diff --git a/src/corelib/kernel/qmetatype.h b/src/corelib/kernel/qmetatype.h
index 9659c015ff..2c2dbeef9d 100644
--- a/src/corelib/kernel/qmetatype.h
+++ b/src/corelib/kernel/qmetatype.h
@@ -113,6 +113,7 @@ inline Q_DECL_CONSTEXPR int qMetaTypeId();
     F(QJsonObject, 46, QJsonObject) \
     F(QJsonArray, 47, QJsonArray) \
     F(QJsonDocument, 48, QJsonDocument) \
+    F(QPersistentModelIndex, 50, QPersistentModelIndex) \
 
 #define QT_FOR_EACH_STATIC_CORE_POINTER(F)\
     F(QObjectStar, 39, QObject*)
@@ -407,7 +408,7 @@ public:
         QT_FOR_EACH_STATIC_TYPE(QT_DEFINE_METATYPE_ID)
 
         FirstCoreType = Bool,
-        LastCoreType = QByteArrayList,
+        LastCoreType = QPersistentModelIndex,
         FirstGuiType = QFont,
         LastGuiType = QPolygonF,
         FirstWidgetsType = QSizePolicy,
@@ -431,7 +432,7 @@ public:
         QLocale = 18, QRect = 19, QRectF = 20, QSize = 21, QSizeF = 22,
         QLine = 23, QLineF = 24, QPoint = 25, QPointF = 26, QRegExp = 27,
         QEasingCurve = 29, QUuid = 30, QVariant = 41, QModelIndex = 42,
-        QRegularExpression = 44,
+        QPersistentModelIndex = 50, QRegularExpression = 44,
         QJsonValue = 45, QJsonObject = 46, QJsonArray = 47, QJsonDocument = 48,
         QByteArrayList = 49, QObjectStar = 39, SChar = 40,
         Void = 43,
diff --git a/src/corelib/kernel/qmetatype_p.h b/src/corelib/kernel/qmetatype_p.h
index 7880baf0f1..7c0c984c9c 100644
--- a/src/corelib/kernel/qmetatype_p.h
+++ b/src/corelib/kernel/qmetatype_p.h
@@ -192,6 +192,7 @@ template<> struct TypeDefinition<QJsonDocument> { static const bool IsAvailable
 template<> struct TypeDefinition<QJsonObject> { static const bool IsAvailable = false; };
 template<> struct TypeDefinition<QJsonValue> { static const bool IsAvailable = false; };
 template<> struct TypeDefinition<QModelIndex> { static const bool IsAvailable = false; };
+template<> struct TypeDefinition<QPersistentModelIndex> { static const bool IsAvailable = false; };
 template<> struct TypeDefinition<QUrl> { static const bool IsAvailable = false; };
 template<> struct TypeDefinition<QByteArrayList> { static const bool IsAvailable = false; };
 #endif
diff --git a/src/corelib/kernel/qvariant.cpp b/src/corelib/kernel/qvariant.cpp
index b14c9ed167..9ae6c779c0 100644
--- a/src/corelib/kernel/qvariant.cpp
+++ b/src/corelib/kernel/qvariant.cpp
@@ -390,7 +390,25 @@ static bool convert(const QVariant::Private *d, int t, void *result, bool *ok)
             return false;
         }
         break;
-#endif
+    case QVariant::ModelIndex:
+        switch (d->type) {
+        case QVariant::PersistentModelIndex:
+            *static_cast<QModelIndex *>(result) = QModelIndex(*v_cast<QPersistentModelIndex>(d));
+            break;
+        default:
+            return false;
+        }
+        break;
+    case QVariant::PersistentModelIndex:
+        switch (d->type) {
+        case QVariant::ModelIndex:
+            *static_cast<QPersistentModelIndex *>(result) = QPersistentModelIndex(*v_cast<QModelIndex>(d));
+            break;
+        default:
+            return false;
+        }
+        break;
+#endif // QT_BOOTSTRAPPED
     case QVariant::String: {
         QString *str = static_cast<QString *>(result);
         switch (d->type) {
@@ -1208,6 +1226,7 @@ Q_CORE_EXPORT void QVariantPrivate::registerHandler(const int /* Modules::Names
     \value EasingCurve a QEasingCurve
     \value Uuid a QUuid
     \value ModelIndex a QModelIndex
+    \value PersistentModelIndex a QPersistentModelIndex (since 5.5)
     \value Font  a QFont
     \value Hash a QVariantHash
     \value Icon  a QIcon
@@ -1455,7 +1474,14 @@ QVariant::QVariant(const char *val)
     \since 5.0
     \fn QVariant::QVariant(const QModelIndex &val)
 
-    Constructs a new variant with an modelIndex value, \a val.
+    Constructs a new variant with a QModelIndex value, \a val.
+*/
+
+/*!
+    \since 5.5
+    \fn QVariant::QVariant(const QPersistentModelIndex &val)
+
+    Constructs a new variant with a QPersistentModelIndex value, \a val.
 */
 
 /*!
@@ -1763,6 +1789,9 @@ QVariant::QVariant(const QUuid &uuid)
 QVariant::QVariant(const QModelIndex &modelIndex)
     : d(ModelIndex)
 { v_construct<QModelIndex>(&d, modelIndex); }
+QVariant::QVariant(const QPersistentModelIndex &modelIndex)
+    : d(PersistentModelIndex)
+{ v_construct<QPersistentModelIndex>(&d, modelIndex); }
 QVariant::QVariant(const QJsonValue &jsonValue)
     : d(QMetaType::QJsonValue)
 { v_construct<QJsonValue>(&d, jsonValue); }
@@ -2492,7 +2521,7 @@ QUuid QVariant::toUuid() const
     Returns the variant as a QModelIndex if the variant has userType() \l
     QModelIndex; otherwise returns a default constructed QModelIndex.
 
-    \sa canConvert(), convert()
+    \sa canConvert(), convert(), toPersistentModelIndex()
 */
 QModelIndex QVariant::toModelIndex() const
 {
@@ -2500,6 +2529,19 @@ QModelIndex QVariant::toModelIndex() const
 }
 
 /*!
+    \since 5.5
+
+    Returns the variant as a QPersistentModelIndex if the variant has userType() \l
+    QPersistentModelIndex; otherwise returns a default constructed QPersistentModelIndex.
+
+    \sa canConvert(), convert(), toModelIndex()
+*/
+QModelIndex QVariant::toPersistentModelIndex() const
+{
+    return qVariantToHelper<QPersistentModelIndex>(d, handlerManager);
+}
+
+/*!
     \since 5.0
 
     Returns the variant as a QJsonValue if the variant has userType() \l
@@ -2966,6 +3008,10 @@ static bool canConvertMetaObject(int fromId, int toId, QObject *fromObject)
 */
 bool QVariant::canConvert(int targetTypeId) const
 {
+    if ((targetTypeId == QMetaType::QModelIndex && d.type == QMetaType::QPersistentModelIndex)
+        || (targetTypeId == QMetaType::QPersistentModelIndex && d.type == QMetaType::QModelIndex))
+        return true;
+
     if (targetTypeId == QMetaType::QVariantList
             && (d.type == QMetaType::QVariantList
               || d.type == QMetaType::QStringList
diff --git a/src/corelib/kernel/qvariant.h b/src/corelib/kernel/qvariant.h
index b6a4133582..d9eca94391 100644
--- a/src/corelib/kernel/qvariant.h
+++ b/src/corelib/kernel/qvariant.h
@@ -156,6 +156,7 @@ class Q_CORE_EXPORT QVariant
         EasingCurve = QMetaType::QEasingCurve,
         Uuid = QMetaType::QUuid,
         ModelIndex = QMetaType::QModelIndex,
+        PersistentModelIndex = QMetaType::QPersistentModelIndex,
         LastCoreType = QMetaType::LastCoreType,
 
         Font = QMetaType::QFont,
@@ -245,6 +246,7 @@ class Q_CORE_EXPORT QVariant
     QVariant(const QEasingCurve &easing);
     QVariant(const QUuid &uuid);
     QVariant(const QModelIndex &modelIndex);
+    QVariant(const QPersistentModelIndex &modelIndex);
     QVariant(const QJsonValue &jsonValue);
     QVariant(const QJsonObject &jsonObject);
     QVariant(const QJsonArray &jsonArray);
@@ -318,6 +320,7 @@ class Q_CORE_EXPORT QVariant
     QEasingCurve toEasingCurve() const;
     QUuid toUuid() const;
     QModelIndex toModelIndex() const;
+    QModelIndex toPersistentModelIndex() const;
     QJsonValue toJsonValue() const;
     QJsonObject toJsonObject() const;
     QJsonArray toJsonArray() const;
diff --git a/src/corelib/thread/qbasicatomic.h b/src/corelib/thread/qbasicatomic.h
index 16a27862c2..ecf39d699f 100644
--- a/src/corelib/thread/qbasicatomic.h
+++ b/src/corelib/thread/qbasicatomic.h
@@ -39,6 +39,14 @@
 #if defined(QT_BOOTSTRAPPED)
 #  include <QtCore/qatomic_bootstrap.h>
 
+// The following two are used for testing only.
+// Note that we don't check the compiler support -- you had better
+// know what you're doing if you set them
+#elif defined(QT_ATOMIC_FORCE_CXX11)
+#  include <QtCore/qatomic_cxx11.h>
+#elif defined(QT_ATOMIC_FORCE_GCC)
+#  include <QtCore/qatomic_gcc.h>
+
 // Compiler dependent implementation
 #elif defined(Q_CC_MSVC)
 #  include <QtCore/qatomic_msvc.h>
diff --git a/src/corelib/tools/qdatetime.cpp b/src/corelib/tools/qdatetime.cpp
index eeefea8137..e5fbf5af5e 100644
--- a/src/corelib/tools/qdatetime.cpp
+++ b/src/corelib/tools/qdatetime.cpp
@@ -2607,7 +2607,6 @@ QDateTimePrivate::QDateTimePrivate(const QDate &toDate, const QTime &toTime,
 void QDateTimePrivate::setTimeSpec(Qt::TimeSpec spec, int offsetSeconds)
 {
     clearValidDateTime();
-    clearTimeZoneCached();
     clearSetToDaylightStatus();
 
 #ifndef QT_BOOTSTRAPPED
@@ -2707,27 +2706,44 @@ QDateTimePrivate::DaylightStatus QDateTimePrivate::daylightStatus() const
     return UnknownDaylightTime;
 }
 
+qint64 QDateTimePrivate::toMSecsSinceEpoch() const
+{
+    switch (m_spec) {
+    case Qt::OffsetFromUTC:
+    case Qt::UTC:
+        return (m_msecs - (m_offsetFromUtc * 1000));
+
+    case Qt::LocalTime:
+        // recalculate the local timezone
+        return localMSecsToEpochMSecs(m_msecs);
+
+    case Qt::TimeZone:
+#ifndef QT_BOOTSTRAPPED
+        return zoneMSecsToEpochMSecs(m_msecs, m_timeZone);
+#endif
+        break;
+    }
+    Q_UNREACHABLE();
+    return 0;
+}
+
 // Check the UTC / offsetFromUTC validity
 void QDateTimePrivate::checkValidDateTime()
 {
     switch (m_spec) {
     case Qt::OffsetFromUTC:
     case Qt::UTC:
+        // for these, a valid date and a valid time imply a valid QDateTime
         if (isValidDate() && isValidTime())
             setValidDateTime();
         else
             clearValidDateTime();
         break;
     case Qt::TimeZone:
-        // Defer checking until required as can be expensive
-        clearValidDateTime();
-        clearTimeZoneCached();
-        m_offsetFromUtc = 0;
-        break;
     case Qt::LocalTime:
-        // Defer checking until required as can be expensive
-        clearValidDateTime();
-        m_offsetFromUtc = 0;
+        // for these, we need to check whether the timezone is valid and whether
+        // the time is valid in that timezone. Expensive, but no other option.
+        refreshDateTime();
         break;
     }
 }
@@ -2741,12 +2757,6 @@ void QDateTimePrivate::refreshDateTime()
         // Always set by setDateTime so just return
         return;
     case Qt::TimeZone:
-        // If already cached then don't need to refresh as tz won't change
-        if (isTimeZoneCached())
-            return;
-        // Flag that will have a cached result after calculations
-        setTimeZoneCached();
-        break;
     case Qt::LocalTime:
         break;
     }
@@ -3082,7 +3092,6 @@ bool QDateTime::isNull() const
 
 bool QDateTime::isValid() const
 {
-    d->refreshDateTime();
     return (d->isValidDateTime());
 }
 
@@ -3143,13 +3152,11 @@ Qt::TimeSpec QDateTime::timeSpec() const
 QTimeZone QDateTime::timeZone() const
 {
     switch (d->m_spec) {
-    case Qt::OffsetFromUTC:
-        if (!d->m_timeZone.isValid())
-            d->m_timeZone = QTimeZone(d->m_offsetFromUtc);
-        return d->m_timeZone;
     case Qt::UTC:
         return QTimeZone::utc();
+    case Qt::OffsetFromUTC:
     case Qt::TimeZone:
+        Q_ASSERT(d->m_timeZone.isValid());
         return d->m_timeZone;
     case Qt::LocalTime:
         return QTimeZone::systemTimeZone();
@@ -3178,7 +3185,6 @@ QTimeZone QDateTime::timeZone() const
 
 int QDateTime::offsetFromUtc() const
 {
-    d->refreshDateTime();
     return d->m_offsetFromUtc;
 }
 
@@ -3350,7 +3356,7 @@ void QDateTime::setTimeZone(const QTimeZone &toZone)
     d->m_spec = Qt::TimeZone;
     d->m_offsetFromUtc = 0;
     d->m_timeZone = toZone;
-    d->m_status = d->m_status & ~QDateTimePrivate::ValidDateTime & ~QDateTimePrivate::TimeZoneCached;
+    d->refreshDateTime();
 }
 #endif // QT_BOOTSTRAPPED
 
@@ -3371,7 +3377,6 @@ void QDateTime::setTimeZone(const QTimeZone &toZone)
 */
 qint64 QDateTime::toMSecsSinceEpoch() const
 {
-    d->refreshDateTime();
     return d->toMSecsSinceEpoch();
 }
 
@@ -3453,8 +3458,8 @@ void QDateTime::setMSecsSinceEpoch(qint64 msecs)
         d->m_status = d->m_status
                     | QDateTimePrivate::ValidDate
                     | QDateTimePrivate::ValidTime
-                    | QDateTimePrivate::ValidDateTime
-                    | QDateTimePrivate::TimeZoneCached;
+                    | QDateTimePrivate::ValidDateTime;
+        d->refreshDateTime();
 #endif // QT_BOOTSTRAPPED
         break;
     case Qt::LocalTime: {
diff --git a/src/corelib/tools/qdatetime.h b/src/corelib/tools/qdatetime.h
index 784aced71a..88288872df 100644
--- a/src/corelib/tools/qdatetime.h
+++ b/src/corelib/tools/qdatetime.h
@@ -326,7 +326,7 @@ private:
     // ### Qt6: Using a private here has high impact on runtime
     // on users such as QFileInfo. In Qt 6, the data members
     // should be inlined.
-    QExplicitlySharedDataPointer<QDateTimePrivate> d;
+    QSharedDataPointer<QDateTimePrivate> d;
 
 #ifndef QT_NO_DATASTREAM
     friend Q_CORE_EXPORT QDataStream &operator<<(QDataStream &, const QDateTime &);
diff --git a/src/corelib/tools/qdatetime_p.h b/src/corelib/tools/qdatetime_p.h
index a139390a9d..b8934f7f70 100644
--- a/src/corelib/tools/qdatetime_p.h
+++ b/src/corelib/tools/qdatetime_p.h
@@ -79,10 +79,9 @@ public:
     enum StatusFlag {
         NullDate            = 0x01,
         NullTime            = 0x02,
-        ValidDate           = 0x04,
-        ValidTime           = 0x08,
-        ValidDateTime       = 0x10,
-        TimeZoneCached      = 0x20,
+        ValidDate           = 0x04, // just the date field
+        ValidTime           = 0x08, // just the time field
+        ValidDateTime       = 0x10, // the whole object (including timezone)
         SetToStandardTime   = 0x40,
         SetToDaylightTime   = 0x80
     };
@@ -120,7 +119,7 @@ public:
     DaylightStatus daylightStatus() const;
 
     // Returns msecs since epoch, assumes offset value is current
-    inline qint64 toMSecsSinceEpoch() const { return (m_msecs - (m_offsetFromUtc * 1000)); }
+    inline qint64 toMSecsSinceEpoch() const;
 
     void checkValidDateTime();
     void refreshDateTime();
@@ -133,14 +132,11 @@ public:
     inline bool isValidDateTime() const { return m_status & ValidDateTime; }
     inline void setValidDateTime() { m_status |= ValidDateTime; }
     inline void clearValidDateTime() { m_status &= ~ValidDateTime; }
-    inline bool isTimeZoneCached() const { return m_status & TimeZoneCached; }
-    inline void setTimeZoneCached() { m_status |= TimeZoneCached; }
-    inline void clearTimeZoneCached() { m_status &= ~TimeZoneCached; }
     inline void clearSetToDaylightStatus() { m_status &= ~(SetToStandardTime | SetToDaylightTime); }
 
 #ifndef QT_BOOTSTRAPPED
     static qint64 zoneMSecsToEpochMSecs(qint64 msecs, const QTimeZone &zone,
-                                        QDate *localDate, QTime *localTime);
+                                        QDate *localDate = 0, QTime *localTime = 0);
 #endif // QT_BOOTSTRAPPED
 
     static inline qint64 minJd() { return QDate::minJd(); }
diff --git a/src/corelib/tools/qsharedpointer_impl.h b/src/corelib/tools/qsharedpointer_impl.h
index 8cccc83e9d..9e6b48a97d 100644
--- a/src/corelib/tools/qsharedpointer_impl.h
+++ b/src/corelib/tools/qsharedpointer_impl.h
@@ -247,6 +247,7 @@ namespace QtSharedPointer {
             ExternalRefCountWithContiguousData *that =
                     static_cast<ExternalRefCountWithContiguousData *>(self);
             that->data.~T();
+            Q_UNUSED(that); // MSVC warns if T has a trivial destructor
         }
         static void safetyCheckDeleter(ExternalRefCountData *self)
         {
diff --git a/src/corelib/tools/qstringalgorithms_p.h b/src/corelib/tools/qstringalgorithms_p.h
index 1481b194eb..b4be5c7ec7 100644
--- a/src/corelib/tools/qstringalgorithms_p.h
+++ b/src/corelib/tools/qstringalgorithms_p.h
@@ -114,7 +114,7 @@ template <typename StringType> struct QStringAlgorithms
             return str;
         const Char *src = str.cbegin();
         const Char *end = str.cend();
-        NakedStringType result = isConst ?
+        NakedStringType result = isConst || !str.isDetached() ?
                                      StringType(str.size(), Qt::Uninitialized) :
                                      qMove(str);