Replace QFlagPointer with QTaggedPointer

The latter has the advantage of allowing the use of a real type for the
tag, instead of the generic flag/flag2 boolean accessors.

Change-Id: Icc9e854ce4af3eb5808a4bed45aa22f377e223da
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

17 files changed, 169 insertions, 319 deletions

diff --git a/src/qml/qml/ftw/qfieldlist_p.h b/src/qml/qml/ftw/qfieldlist_p.h
index 2bf07fb20d..66602daab2 100644
--- a/src/qml/qml/ftw/qfieldlist_p.h
+++ b/src/qml/qml/ftw/qfieldlist_p.h
@@ -52,11 +52,12 @@
 //
 
 #include <QtCore/qglobal.h>
+#include <QtCore/qtaggedpointer.h>
 
 #include <private/qflagpointer_p.h>
 
 // QForwardFieldList is a super simple linked list that can only prepend
-template<class N, N *N::*nextMember>
+template<class N, N *N::*nextMember, typename Tag = QtPrivate::TagInfo<N>>
 class QForwardFieldList
 {
 public:
@@ -72,17 +73,10 @@ public:
 
     static inline N *next(N *v);
 
-    inline bool flag() const;
-    inline void setFlag();
-    inline void clearFlag();
-    inline void setFlagValue(bool);
-
-    inline bool flag2() const;
-    inline void setFlag2();
-    inline void clearFlag2();
-    inline void setFlag2Value(bool);
+    inline Tag tag() const;
+    inline void setTag(Tag t);
 private:
-    QFlagPointer<N> _first;
+    QTaggedPointer<N, Tag> _first;
 };
 
 // QFieldList is a simple linked list, that can append and prepend and also
@@ -108,8 +102,10 @@ public:
     inline void insertAfter(N *, QFieldList<N, nextMember> &);
 
     inline void copyAndClear(QFieldList<N, nextMember> &);
-    inline void copyAndClearAppend(QForwardFieldList<N, nextMember> &);
-    inline void copyAndClearPrepend(QForwardFieldList<N, nextMember> &);
+    template <typename Tag>
+    inline void copyAndClearAppend(QForwardFieldList<N, nextMember, Tag> &);
+    template <typename Tag>
+    inline void copyAndClearPrepend(QForwardFieldList<N, nextMember, Tag> &);
 
     static inline N *next(N *v);
 
@@ -124,21 +120,21 @@ private:
     quint32 _count:31;
 };
 
-template<class N, N *N::*nextMember>
-QForwardFieldList<N, nextMember>::QForwardFieldList()
+template<class N, N *N::*nextMember, typename Tag>
+QForwardFieldList<N, nextMember, Tag>::QForwardFieldList()
 {
 }
 
-template<class N, N *N::*nextMember>
-N *QForwardFieldList<N, nextMember>::first() const
+template<class N, N *N::*nextMember, typename Tag>
+N *QForwardFieldList<N, nextMember, Tag>::first() const
 {
-    return *_first;
+    return _first.data();
 }
 
-template<class N, N *N::*nextMember>
-N *QForwardFieldList<N, nextMember>::takeFirst()
+template<class N, N *N::*nextMember, typename Tag>
+N *QForwardFieldList<N, nextMember, Tag>::takeFirst()
 {
-    N *value = *_first;
+    N *value = _first.data();
     if (value) {
         _first = next(value);
         value->*nextMember = nullptr;
@@ -146,85 +142,49 @@ N *QForwardFieldList<N, nextMember>::takeFirst()
     return value;
 }
 
-template<class N, N *N::*nextMember>
-void QForwardFieldList<N, nextMember>::prepend(N *v)
+template<class N, N *N::*nextMember, typename Tag>
+void QForwardFieldList<N, nextMember, Tag>::prepend(N *v)
 {
     Q_ASSERT(v->*nextMember == nullptr);
-    v->*nextMember = *_first;
+    v->*nextMember = _first.data();
     _first = v;
 }
 
-template<class N, N *N::*nextMember>
-bool QForwardFieldList<N, nextMember>::isEmpty() const
+template<class N, N *N::*nextMember, typename Tag>
+bool QForwardFieldList<N, nextMember, Tag>::isEmpty() const
 {
     return _first.isNull();
 }
 
-template<class N, N *N::*nextMember>
-bool QForwardFieldList<N, nextMember>::isOne() const
+template<class N, N *N::*nextMember, typename Tag>
+bool QForwardFieldList<N, nextMember, Tag>::isOne() const
 {
-    return *_first && _first->*nextMember == 0;
+    return _first.data() && _first->*nextMember == 0;
 }
 
-template<class N, N *N::*nextMember>
-bool QForwardFieldList<N, nextMember>::isMany() const
+template<class N, N *N::*nextMember, typename Tag>
+bool QForwardFieldList<N, nextMember, Tag>::isMany() const
 {
-    return *_first && _first->*nextMember != 0;
+    return _first.data() && _first->*nextMember != 0;
 }
 
-template<class N, N *N::*nextMember>
-N *QForwardFieldList<N, nextMember>::next(N *v)
+template<class N, N *N::*nextMember, typename Tag>
+N *QForwardFieldList<N, nextMember, Tag>::next(N *v)
 {
     Q_ASSERT(v);
     return v->*nextMember;
 }
 
-template<class N, N *N::*nextMember>
-bool QForwardFieldList<N, nextMember>::flag() const
-{
-    return _first.flag();
-}
-
-template<class N, N *N::*nextMember>
-void QForwardFieldList<N, nextMember>::setFlag()
-{
-    _first.setFlag();
-}
-
-template<class N, N *N::*nextMember>
-void QForwardFieldList<N, nextMember>::clearFlag()
-{
-    _first.clearFlag();
-}
-
-template<class N, N *N::*nextMember>
-void QForwardFieldList<N, nextMember>::setFlagValue(bool v)
-{
-    _first.setFlagValue(v);
-}
-
-template<class N, N *N::*nextMember>
-bool QForwardFieldList<N, nextMember>::flag2() const
-{
-    return _first.flag2();
-}
-
-template<class N, N *N::*nextMember>
-void QForwardFieldList<N, nextMember>::setFlag2()
+template<class N, N *N::*nextMember, typename Tag>
+Tag QForwardFieldList<N, nextMember, Tag>::tag() const
 {
-    _first.setFlag2();
+    return _first.tag();
 }
 
-template<class N, N *N::*nextMember>
-void QForwardFieldList<N, nextMember>::clearFlag2()
-{
-    _first.clearFlag2();
-}
-
-template<class N, N *N::*nextMember>
-void QForwardFieldList<N, nextMember>::setFlag2Value(bool v)
+template<class N, N *N::*nextMember, typename Tag>
+void QForwardFieldList<N, nextMember, Tag>::setTag(Tag t)
 {
-    _first.setFlag2Value(v);
+    _first.setTag(t);
 }
 
 template<class N, N *N::*nextMember>
@@ -380,7 +340,8 @@ void QFieldList<N, nextMember>::copyAndClear(QFieldList<N, nextMember> &o)
 }
 
 template<class N, N *N::*nextMember>
-void QFieldList<N, nextMember>::copyAndClearAppend(QForwardFieldList<N, nextMember> &o)
+template <typename Tag>
+void QFieldList<N, nextMember>::copyAndClearAppend(QForwardFieldList<N, nextMember, Tag> &o)
 {
     _first = 0;
     _last = 0;
@@ -389,7 +350,8 @@ void QFieldList<N, nextMember>::copyAndClearAppend(QForwardFieldList<N, nextMemb
 }
 
 template<class N, N *N::*nextMember>
-void QFieldList<N, nextMember>::copyAndClearPrepend(QForwardFieldList<N, nextMember> &o)
+template <typename Tag>
+void QFieldList<N, nextMember>::copyAndClearPrepend(QForwardFieldList<N, nextMember, Tag> &o)
 {
     _first = nullptr;
     _last = nullptr;
diff --git a/src/qml/qml/ftw/qflagpointer_p.h b/src/qml/qml/ftw/qflagpointer_p.h
index a10e57aeca..5cdf973352 100644
--- a/src/qml/qml/ftw/qflagpointer_p.h
+++ b/src/qml/qml/ftw/qflagpointer_p.h
@@ -66,43 +66,6 @@ template <> struct QFlagPointerAlignment<void>
 };
 }
 
-template<typename T>
-class QFlagPointer {
-public:
-    inline QFlagPointer();
-    inline QFlagPointer(T *);
-    inline QFlagPointer(const QFlagPointer<T> &o);
-
-    inline bool isNull() const;
-
-    inline bool flag() const;
-    inline void setFlag();
-    inline void clearFlag();
-    inline void setFlagValue(bool);
-
-    inline bool flag2() const;
-    inline void setFlag2();
-    inline void clearFlag2();
-    inline void setFlag2Value(bool);
-
-    inline QFlagPointer<T> &operator=(const QFlagPointer &o);
-    inline QFlagPointer<T> &operator=(T *);
-
-    inline T *operator->() const;
-    inline T *operator*() const;
-
-    inline T *data() const;
-
-    inline explicit operator bool() const;
-
-private:
-    quintptr ptr_value = 0;
-
-    static const quintptr FlagBit = 0x1;
-    static const quintptr Flag2Bit = 0x2;
-    static const quintptr FlagsMask = FlagBit | Flag2Bit;
-};
-
 template<typename T, typename T2>
 class QBiPointer {
 public:
@@ -135,121 +98,6 @@ private:
     static const quintptr FlagsMask = FlagBit | Flag2Bit;
 };
 
-template<typename T>
-QFlagPointer<T>::QFlagPointer()
-{
-}
-
-template<typename T>
-QFlagPointer<T>::QFlagPointer(T *v)
-: ptr_value(quintptr(v))
-{
-    Q_STATIC_ASSERT_X(Q_ALIGNOF(T) >= 4, "Type T does not have sufficient alignment");
-    Q_ASSERT((ptr_value & FlagsMask) == 0);
-}
-
-template<typename T>
-QFlagPointer<T>::QFlagPointer(const QFlagPointer<T> &o)
-: ptr_value(o.ptr_value)
-{
-}
-
-template<typename T>
-bool QFlagPointer<T>::isNull() const
-{
-    return 0 == (ptr_value & (~FlagsMask));
-}
-
-template<typename T>
-bool QFlagPointer<T>::flag() const
-{
-    return ptr_value & FlagBit;
-}
-
-template<typename T>
-void QFlagPointer<T>::setFlag()
-{
-    ptr_value |= FlagBit;
-}
-
-template<typename T>
-void QFlagPointer<T>::clearFlag()
-{
-    ptr_value &= ~FlagBit;
-}
-
-template<typename T>
-void QFlagPointer<T>::setFlagValue(bool v)
-{
-    if (v) setFlag();
-    else clearFlag();
-}
-
-template<typename T>
-bool QFlagPointer<T>::flag2() const
-{
-    return ptr_value & Flag2Bit;
-}
-
-template<typename T>
-void QFlagPointer<T>::setFlag2()
-{
-    ptr_value|= Flag2Bit;
-}
-
-template<typename T>
-void QFlagPointer<T>::clearFlag2()
-{
-    ptr_value &= ~Flag2Bit;
-}
-
-template<typename T>
-void QFlagPointer<T>::setFlag2Value(bool v)
-{
-    if (v) setFlag2();
-    else clearFlag2();
-}
-
-template<typename T>
-QFlagPointer<T> &QFlagPointer<T>::operator=(const QFlagPointer &o)
-{
-    ptr_value = o.ptr_value;
-    return *this;
-}
-
-template<typename T>
-QFlagPointer<T> &QFlagPointer<T>::operator=(T *o)
-{
-    Q_ASSERT((quintptr(o) & FlagsMask) == 0);
-
-    ptr_value = quintptr(o) | (ptr_value & FlagsMask);
-    return *this;
-}
-
-template<typename T>
-T *QFlagPointer<T>::operator->() const
-{
-    return (T *)(ptr_value & ~FlagsMask);
-}
-
-template<typename T>
-T *QFlagPointer<T>::operator*() const
-{
-    return (T *)(ptr_value & ~FlagsMask);
-}
-
-template<typename T>
-T *QFlagPointer<T>::data() const
-{
-    return (T *)(ptr_value & ~FlagsMask);
-}
-
-template<typename T>
-QFlagPointer<T>::operator bool() const
-{
-    return data() != nullptr;
-}
-
 template<typename T, typename T2>
 QBiPointer<T, T2>::QBiPointer()
 {
diff --git a/src/qml/qml/ftw/qlazilyallocated_p.h b/src/qml/qml/ftw/qlazilyallocated_p.h
index 9073e41558..2bac84afb3 100644
--- a/src/qml/qml/ftw/qlazilyallocated_p.h
+++ b/src/qml/qml/ftw/qlazilyallocated_p.h
@@ -52,12 +52,11 @@
 //
 
 #include <QtCore/qglobal.h>
-
-#include <private/qflagpointer_p.h>
+#include <QtCore/qtaggedpointer.h>
 
 QT_BEGIN_NAMESPACE
 
-template<typename T>
+template<typename T, typename Tag = typename QtPrivate::TagInfo<T>::TagType>
 class QLazilyAllocated {
 public:
     inline QLazilyAllocated();
@@ -70,73 +69,59 @@ public:
     inline T &value();
     inline const T &value() const;
 
-    inline bool flag() const;
-    inline void setFlag();
-    inline void clearFlag();
-    inline void setFlagValue(bool);
+    inline Tag tag() const;
+    inline void setTag(Tag t);
 private:
-    mutable QFlagPointer<T> d;
+    mutable QTaggedPointer<T, Tag> d;
 };
 
-template<typename T>
-QLazilyAllocated<T>::QLazilyAllocated()
+template<typename T, typename Tag>
+QLazilyAllocated<T, Tag>::QLazilyAllocated()
 {
 }
 
-template<typename T>
-QLazilyAllocated<T>::~QLazilyAllocated()
+template<typename T, typename Tag>
+QLazilyAllocated<T, Tag>::~QLazilyAllocated()
 {
-    delete *d;
+    delete d.data();
 }
 
-template<typename T>
-bool QLazilyAllocated<T>::isAllocated() const
+template<typename T, typename Tag>
+bool QLazilyAllocated<T, Tag>::isAllocated() const
 {
     return !d.isNull();
 }
 
-template<typename T>
-T &QLazilyAllocated<T>::value()
+template<typename T, typename Tag>
+T &QLazilyAllocated<T, Tag>::value()
 {
     if (d.isNull()) d = new T;
-    return *(*d);
+    return *d;
 }
 
-template<typename T>
-const T &QLazilyAllocated<T>::value() const
+template<typename T, typename Tag>
+const T &QLazilyAllocated<T, Tag>::value() const
 {
     if (d.isNull()) d = new T;
-    return *(*d);
-}
-
-template<typename T>
-T *QLazilyAllocated<T>::operator->() const
-{
     return *d;
 }
 
-template<typename T>
-bool QLazilyAllocated<T>::flag() const
-{
-    return d.flag();
-}
-
-template<typename T>
-void QLazilyAllocated<T>::setFlag()
+template<typename T, typename Tag>
+T *QLazilyAllocated<T, Tag>::operator->() const
 {
-    d.setFlag();
+    return d.data();
 }
 
-template<typename T>
-void QLazilyAllocated<T>::clearFlag()
+template<typename T, typename Tag>
+Tag QLazilyAllocated<T, Tag>::tag() const
 {
-    d.clearFlag();
+    return d.tag();
 }
 
-template<typename T>
-void QLazilyAllocated<T>::setFlagValue(bool v)
+template<typename T, typename Tag>
+void QLazilyAllocated<T, Tag>::setTag(Tag t)
 {
-    d.setFlagValue(v);
+    d.setTag(t);
 }
 
 QT_END_NAMESPACE
diff --git a/src/qml/qml/ftw/qlinkedstringhash_p.h b/src/qml/qml/ftw/qlinkedstringhash_p.h
index 67ced7fbbf..495d78ea2f 100644
--- a/src/qml/qml/ftw/qlinkedstringhash_p.h
+++ b/src/qml/qml/ftw/qlinkedstringhash_p.h
@@ -223,7 +223,7 @@ public:
     {
         if (auto *node = iter.node()) {
             QHashedString key(node->key());
-            while ((node = static_cast<typename QLinkedStringHash<T>::Node *>(*node->next))) {
+            while ((node = static_cast<typename QLinkedStringHash<T>::Node *>(node->next.data()))) {
                 if (node->equals(key))
                     return QLinkedStringHash<T>::iterator(node);
             }
diff --git a/src/qml/qml/ftw/qstringhash_p.h b/src/qml/qml/ftw/qstringhash_p.h
index fc73fdfa50..125e160500 100644
--- a/src/qml/qml/ftw/qstringhash_p.h
+++ b/src/qml/qml/ftw/qstringhash_p.h
@@ -56,6 +56,7 @@
 
 #include <QtCore/qbytearray.h>
 #include <QtCore/qstring.h>
+#include <QtCore/qtaggedpointer.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -104,7 +105,12 @@ public:
             QTypedArrayData<ushort>::deallocate(arrayData);
     }
 
-    QFlagPointer<QStringHashNode> next;
+    enum Tag {
+        NodeIsCString,
+        NodeIsQString
+    };
+
+    QTaggedPointer<QStringHashNode, Tag> next;
 
     qint32 length = 0;
     quint32 hash = 0;
@@ -126,8 +132,8 @@ public:
         return QHashedString(QString::fromLatin1(ckey, length), hash);
     }
 
-    bool isQString() const { return next.flag(); }
-    void setQString(bool v) { if (v) next.setFlag(); else next.clearFlag(); }
+    bool isQString() const { return next.tag() == NodeIsQString; }
+    void setQString(bool v) { if (v) next.setTag(NodeIsQString); else next.setTag(NodeIsCString); }
 
     inline qsizetype size() const { return length; }
     inline const char *cStrData() const { return ckey; }
@@ -712,7 +718,7 @@ typename QStringHash<T>::Node *QStringHash<T>::findNode(const K &key) const
 
     typename HashedForm<K>::Type hashedKey(hashedString(key));
     while (node && !node->equals(hashedKey))
-        node = (*node->next);
+        node = node->next.data();
 
     return (Node *)node;
 }
diff --git a/src/qml/qml/qqmlabstractbinding_p.h b/src/qml/qml/qqmlabstractbinding_p.h
index fc53be3e7b..96bb0da269 100644
--- a/src/qml/qml/qqmlabstractbinding_p.h
+++ b/src/qml/qml/qqmlabstractbinding_p.h
@@ -92,7 +92,7 @@ public:
     inline QQmlAbstractBinding *nextBinding() const;
 
     inline bool canUseAccessor() const
-    { return m_nextBinding.flag2(); }
+    { return m_nextBinding.tag().testFlag(CanUseAccessor); }
 
     struct RefCount {
         RefCount() {}
@@ -103,6 +103,20 @@ public:
     };
     RefCount ref;
 
+    enum TargetTag {
+        NoTargetTag     = 0x0,
+        UpdatingBinding = 0x1,
+        BindingEnabled  = 0x2
+    };
+    Q_DECLARE_FLAGS(TargetTags, TargetTag)
+
+    enum NextBindingTag {
+        NoBindingTag   = 0x0,
+        AddedToObject  = 0x1,
+        CanUseAccessor = 0x2
+    };
+    Q_DECLARE_FLAGS(NextBindingTags, NextBindingTag)
+
 protected:
     friend class QQmlData;
     friend class QQmlValueTypeProxyBinding;
@@ -116,24 +130,23 @@ protected:
     QQmlPropertyIndex m_targetIndex;
 
     // Pointer is the target object to which the binding binds
-    // flag1 is the updating flag
-    // flag2 is the enabled flag
-    QFlagPointer<QObject> m_target;
+    QTaggedPointer<QObject, TargetTags> m_target;
 
     // Pointer to the next binding in the linked list of bindings.
-    // flag1 is used for addedToObject
-    // flag2 indicates if an accessor is can be used (i.e. there is no interceptor on the target)
-    QFlagPointer<QQmlAbstractBinding> m_nextBinding;
+    QTaggedPointer<QQmlAbstractBinding, NextBindingTags> m_nextBinding;
 };
 
+Q_DECLARE_OPERATORS_FOR_FLAGS(QQmlAbstractBinding::TargetTags)
+Q_DECLARE_OPERATORS_FOR_FLAGS(QQmlAbstractBinding::NextBindingTags)
+
 void QQmlAbstractBinding::setAddedToObject(bool v)
 {
-    m_nextBinding.setFlagValue(v);
+    m_nextBinding.setTag(m_nextBinding.tag().setFlag(AddedToObject, v));
 }
 
 bool QQmlAbstractBinding::isAddedToObject() const
 {
-    return m_nextBinding.flag();
+    return m_nextBinding.tag().testFlag(AddedToObject);
 }
 
 QQmlAbstractBinding *QQmlAbstractBinding::nextBinding() const
diff --git a/src/qml/qml/qqmlbinding.cpp b/src/qml/qml/qqmlbinding.cpp
index 0dcc17d9e8..7de94fe3d5 100644
--- a/src/qml/qml/qqmlbinding.cpp
+++ b/src/qml/qml/qqmlbinding.cpp
@@ -232,7 +232,7 @@ protected:
         QQmlPropertyData *pd = nullptr;
         getPropertyData(&pd, nullptr);
         QQmlBinding *thisPtr = this;
-        pd->writeProperty(*m_target, &thisPtr, flags);
+        pd->writeProperty(m_target.data(), &thisPtr, flags);
     }
 };
 
@@ -546,10 +546,10 @@ void QQmlBinding::setEnabled(bool e, QQmlPropertyData::WriteFlags flags)
     setEnabledFlag(e);
     setNotifyOnValueChanged(e);
 
-    m_nextBinding.setFlag2(); // Always use accessors, only not when:
+    m_nextBinding.setTag(m_nextBinding.tag().setFlag(CanUseAccessor)); // Always use accessors, only not when:
     if (auto interceptorMetaObject = QQmlInterceptorMetaObject::get(targetObject())) {
         if (!m_targetIndex.isValid() || interceptorMetaObject->intercepts(m_targetIndex))
-            m_nextBinding.clearFlag2();
+            m_nextBinding.setTag(m_nextBinding.tag().setFlag(CanUseAccessor, false));
     }
 
     if (e && !wasEnabled)
@@ -606,7 +606,7 @@ bool QQmlBinding::setTarget(QObject *object, const QQmlPropertyData &core, const
     }
     m_targetIndex = QQmlPropertyIndex(coreIndex, valueTypeIndex);
 
-    QQmlData *data = QQmlData::get(*m_target, true);
+    QQmlData *data = QQmlData::get(m_target.data(), true);
     if (!data->propertyCache) {
         data->propertyCache = QQmlEnginePrivate::get(engine())->cache(m_target->metaObject());
         data->propertyCache->addref();
@@ -619,7 +619,7 @@ void QQmlBinding::getPropertyData(QQmlPropertyData **propertyData, QQmlPropertyD
 {
     Q_ASSERT(propertyData);
 
-    QQmlData *data = QQmlData::get(*m_target, false);
+    QQmlData *data = QQmlData::get(m_target.data(), false);
     Q_ASSERT(data);
 
     if (Q_UNLIKELY(!data->propertyCache)) {
diff --git a/src/qml/qml/qqmlbinding_p.h b/src/qml/qml/qqmlbinding_p.h
index 8aeb87df1f..bf73c24c9e 100644
--- a/src/qml/qml/qqmlbinding_p.h
+++ b/src/qml/qml/qqmlbinding_p.h
@@ -153,22 +153,22 @@ private:
 
 bool QQmlBinding::updatingFlag() const
 {
-    return m_target.flag();
+    return m_target.tag().testFlag(UpdatingBinding);
 }
 
 void QQmlBinding::setUpdatingFlag(bool v)
 {
-    m_target.setFlagValue(v);
+    m_target.setTag(m_target.tag().setFlag(UpdatingBinding, v));
 }
 
 bool QQmlBinding::enabledFlag() const
 {
-    return m_target.flag2();
+    return m_target.tag().testFlag(BindingEnabled);
 }
 
 void QQmlBinding::setEnabledFlag(bool v)
 {
-    m_target.setFlag2Value(v);
+    m_target.setTag(m_target.tag().setFlag(BindingEnabled, v));
 }
 
 QT_END_NAMESPACE
diff --git a/src/qml/qml/qqmlcontext_p.h b/src/qml/qml/qqmlcontext_p.h
index ca49cbf963..e1b2e9d41d 100644
--- a/src/qml/qml/qqmlcontext_p.h
+++ b/src/qml/qml/qqmlcontext_p.h
@@ -59,6 +59,7 @@
 #include <QtQml/qqmllist.h>
 
 #include <QtCore/private/qobject_p.h>
+#include <QtCore/qtaggedpointer.h>
 #include <QtQml/private/qqmlrefcount_p.h>
 
 QT_BEGIN_NAMESPACE
diff --git a/src/qml/qml/qqmlcontextdata_p.h b/src/qml/qml/qqmlcontextdata_p.h
index e31a45dea4..ccefd3a05b 100644
--- a/src/qml/qml/qqmlcontextdata_p.h
+++ b/src/qml/qml/qqmlcontextdata_p.h
@@ -278,6 +278,11 @@ private:
     // id guards
     struct ContextGuard : public QQmlGuard<QObject>
     {
+        enum Tag {
+            NoTag,
+            ObjectWasSet
+        };
+
         inline ContextGuard() : m_context(nullptr) {}
         inline ContextGuard &operator=(QObject *obj);
         inline void objectDestroyed(QObject *) override;
@@ -292,7 +297,7 @@ private:
 
     private:
         // Not refcounted, as it always belongs to the QQmlContextData.
-        QFlagPointer<QQmlContextData> m_context;
+        QTaggedPointer<QQmlContextData, Tag> m_context;
         QQmlNotifier m_bindings;
     };
 
@@ -404,7 +409,7 @@ private:
 QQmlContextData::ContextGuard &QQmlContextData::ContextGuard::operator=(QObject *obj)
 {
     QQmlGuard<QObject>::operator=(obj);
-    m_context.setFlag();
+    m_context.setTag(ObjectWasSet);
     m_bindings.notify(); // For alias connections
     return *this;
 }
@@ -419,7 +424,7 @@ void QQmlContextData::ContextGuard::objectDestroyed(QObject *)
 
 bool QQmlContextData::ContextGuard::wasSet() const
 {
-    return m_context.flag();
+    return m_context.tag() == ObjectWasSet;
 }
 
 QT_END_NAMESPACE
diff --git a/src/qml/qml/qqmljavascriptexpression.cpp b/src/qml/qml/qqmljavascriptexpression.cpp
index 3e204c1898..0f83baa893 100644
--- a/src/qml/qml/qqmljavascriptexpression.cpp
+++ b/src/qml/qml/qqmljavascriptexpression.cpp
@@ -129,7 +129,7 @@ QString QQmlJavaScriptExpression::expressionIdentifier() const
 
 void QQmlJavaScriptExpression::setNotifyOnValueChanged(bool v)
 {
-    activeGuards.setFlagValue(v);
+    activeGuards.setTag(v ? NotifyOnValueChanged : NoGuardTag);
     if (!v)
         clearActiveGuards();
 }
diff --git a/src/qml/qml/qqmljavascriptexpression_p.h b/src/qml/qml/qqmljavascriptexpression_p.h
index b52e978938..f90b399b0a 100644
--- a/src/qml/qml/qqmljavascriptexpression_p.h
+++ b/src/qml/qml/qqmljavascriptexpression_p.h
@@ -52,6 +52,7 @@
 //
 
 #include <QtCore/qglobal.h>
+#include <QtCore/qtaggedpointer.h>
 #include <QtQml/qqmlerror.h>
 #include <private/qqmlengine_p.h>
 
@@ -175,10 +176,16 @@ protected:
     //    activeGuards:flag1  - notifyOnValueChanged
     //    activeGuards:flag2  - useSharedContext
     QBiPointer<QObject, DeleteWatcher> m_scopeObject;
-    QForwardFieldList<QQmlJavaScriptExpressionGuard, &QQmlJavaScriptExpressionGuard::next> activeGuards;
 
-    void setTranslationsCaptured(bool captured) { m_error.setFlagValue(captured); }
-    bool translationsCaptured() const { return m_error.flag(); }
+    enum GuardTag {
+        NoGuardTag,
+        NotifyOnValueChanged
+    };
+
+    QForwardFieldList<QQmlJavaScriptExpressionGuard, &QQmlJavaScriptExpressionGuard::next, GuardTag> activeGuards;
+
+    void setTranslationsCaptured(bool captured) { if (captured) m_error.setTag(TranslationsCaptured); else m_error.setTag(NoTag); }
+    bool translationsCaptured() const { return m_error.tag() == TranslationsCaptured; }
 
 private:
     friend class QQmlContextData;
@@ -186,8 +193,13 @@ private:
     friend void QQmlJavaScriptExpressionGuard_callback(QQmlNotifierEndpoint *, void **);
     friend class QQmlTranslationBinding;
 
+    enum Tag {
+        NoTag,
+        TranslationsCaptured
+    };
+
     // m_error:flag1 translationsCapturedDuringEvaluation
-    QFlagPointer<QQmlDelayedError> m_error;
+    QTaggedPointer<QQmlDelayedError> m_error;
 
     // Not refcounted as the context will clear the expressions when destructed.
     QQmlContextData *m_context;
@@ -250,7 +262,7 @@ bool QQmlJavaScriptExpression::DeleteWatcher::wasDeleted() const
 
 bool QQmlJavaScriptExpression::notifyOnValueChanged() const
 {
-    return activeGuards.flag();
+    return activeGuards.tag() == NotifyOnValueChanged;
 }
 
 QObject *QQmlJavaScriptExpression::scopeObject() const
diff --git a/src/qml/qml/qqmlpropertycachevector_p.h b/src/qml/qml/qqmlpropertycachevector_p.h
index 1dff7c61a6..2e09423206 100644
--- a/src/qml/qml/qqmlpropertycachevector_p.h
+++ b/src/qml/qml/qqmlpropertycachevector_p.h
@@ -54,16 +54,23 @@
 #include <private/qflagpointer_p.h>
 #include <private/qqmlpropertycache_p.h>
 
+#include <QtCore/qtaggedpointer.h>
+
 QT_BEGIN_NAMESPACE
 
 class QQmlPropertyCacheVector
 {
 public:
+    enum Tag {
+        NoTag,
+        CacheNeedsVMEMetaObject
+    };
+
     QQmlPropertyCacheVector() {}
     QQmlPropertyCacheVector(QQmlPropertyCacheVector &&other)
         : data(std::move(other.data)) {}
     QQmlPropertyCacheVector &operator=(QQmlPropertyCacheVector &&other) {
-        QVector<QFlagPointer<QQmlPropertyCache>> moved(std::move(other.data));
+        QVector<QTaggedPointer<QQmlPropertyCache, Tag>> moved(std::move(other.data));
         data.swap(moved);
         return *this;
     }
@@ -80,7 +87,7 @@ public:
         data.clear();
     }
 
-    void append(QQmlPropertyCache *cache) { cache->addref(); data.append(cache); }
+    void append(QQmlPropertyCache *cache) { cache->addref(); data.append(QTaggedPointer<QQmlPropertyCache, Tag>(cache)); }
     QQmlPropertyCache *at(int index) const { return data.at(index).data(); }
     void set(int index, const QQmlRefPointer<QQmlPropertyCache> &replacement) {
         if (QQmlPropertyCache *oldCache = data.at(index).data()) {
@@ -92,11 +99,11 @@ public:
         replacement->addref();
     }
 
-    void setNeedsVMEMetaObject(int index) { data[index].setFlag(); }
-    bool needsVMEMetaObject(int index) const { return data.at(index).flag(); }
+    void setNeedsVMEMetaObject(int index) { data[index].setTag(CacheNeedsVMEMetaObject); }
+    bool needsVMEMetaObject(int index) const { return data.at(index).tag() == CacheNeedsVMEMetaObject; }
 private:
     Q_DISABLE_COPY(QQmlPropertyCacheVector)
-    QVector<QFlagPointer<QQmlPropertyCache>> data;
+    QVector<QTaggedPointer<QQmlPropertyCache, Tag>> data;
 };
 
 QT_END_NAMESPACE
diff --git a/src/qml/qml/qqmlvmemetaobject.cpp b/src/qml/qml/qqmlvmemetaobject.cpp
index c107f22df5..856dda1663 100644
--- a/src/qml/qml/qqmlvmemetaobject.cpp
+++ b/src/qml/qml/qqmlvmemetaobject.cpp
@@ -204,7 +204,12 @@ public:
     QQmlVMEMetaObjectEndpoint();
     void tryConnect();
 
-    QFlagPointer<QQmlVMEMetaObject> metaObject;
+    enum Tag {
+        NoTag,
+        EndPointIsConnected
+    };
+
+    QTaggedPointer<QQmlVMEMetaObject, Tag> metaObject;
 };
 
 QQmlVMEMetaObjectEndpoint::QQmlVMEMetaObjectEndpoint()
@@ -223,7 +228,7 @@ void QQmlVMEMetaObjectEndpoint::tryConnect()
     Q_ASSERT(metaObject->compiledObject);
     int aliasId = this - metaObject->aliasEndpoints;
 
-    if (metaObject.flag()) {
+    if (metaObject.tag() == EndPointIsConnected) {
         // This is actually notify
         int sigIdx = metaObject->methodOffset() + aliasId + metaObject->compiledObject->nProperties;
         metaObject->activate(metaObject->object, sigIdx, nullptr);
@@ -258,7 +263,7 @@ void QQmlVMEMetaObjectEndpoint::tryConnect()
                 connect(target, pd->notifyIndex(), ctxt->engine());
         }
 
-        metaObject.setFlag();
+        metaObject.setTag(EndPointIsConnected);
     }
 }
 
diff --git a/src/quick/items/qquickanimatedsprite.cpp b/src/quick/items/qquickanimatedsprite.cpp
index b285fe56ed..c227f8a89d 100644
--- a/src/quick/items/qquickanimatedsprite.cpp
+++ b/src/quick/items/qquickanimatedsprite.cpp
@@ -497,7 +497,7 @@ void QQuickAnimatedSprite::advance(int frames)
 void QQuickAnimatedSprite::maybeUpdate()
 {
     QQuickItemPrivate *priv = QQuickItemPrivate::get(this);
-    const QLazilyAllocated<QQuickItemPrivate::ExtraData> &extraData = priv->extra;
+    const auto &extraData = priv->extra;
     if ((extraData.isAllocated() && extraData->effectRefCount > 0) || priv->effectiveVisible)
         update();
 }
diff --git a/src/quick/items/qquickitem.cpp b/src/quick/items/qquickitem.cpp
index 93f1765811..707f149baf 100644
--- a/src/quick/items/qquickitem.cpp
+++ b/src/quick/items/qquickitem.cpp
@@ -7292,10 +7292,7 @@ Qt::MouseButtons QQuickItem::acceptedMouseButtons() const
 void QQuickItem::setAcceptedMouseButtons(Qt::MouseButtons buttons)
 {
     Q_D(QQuickItem);
-    if (buttons & Qt::LeftButton)
-        d->extra.setFlag();
-    else
-        d->extra.clearFlag();
+    d->extra.setTag(d->extra.tag().setFlag(QQuickItemPrivate::LeftMouseButtonAccepted, buttons & Qt::LeftButton));
 
     buttons &= ~Qt::LeftButton;
     if (buttons || d->extra.isAllocated())
diff --git a/src/quick/items/qquickitem_p.h b/src/quick/items/qquickitem_p.h
index 6f39f3bdd2..395dfee496 100644
--- a/src/quick/items/qquickitem_p.h
+++ b/src/quick/items/qquickitem_p.h
@@ -397,7 +397,7 @@ public:
         QObjectList resourcesList;
 
         // Although acceptedMouseButtons is inside ExtraData, we actually store
-        // the LeftButton flag in the extra.flag() bit.  This is because it is
+        // the LeftButton flag in the extra.tag() bit.  This is because it is
         // extremely common to set acceptedMouseButtons to LeftButton, but very
         // rare to use any of the other buttons.
         Qt::MouseButtons acceptedMouseButtons;
@@ -407,7 +407,14 @@ public:
 
         // 26 bits padding
     };
-    QLazilyAllocated<ExtraData> extra;
+
+    enum ExtraDataTag {
+        NoTag = 0x1,
+        LeftMouseButtonAccepted = 0x2
+    };
+    Q_DECLARE_FLAGS(ExtraDataTags, ExtraDataTag)
+
+    QLazilyAllocated<ExtraData, ExtraDataTags> extra;
     // Contains mask
     QPointer<QObject> mask;
     // If the mask is an Item, inform it that it's being used as a mask (true) or is no longer being used (false)
@@ -663,6 +670,8 @@ public:
     virtual void updatePolish() { }
 };
 
+Q_DECLARE_OPERATORS_FOR_FLAGS(QQuickItemPrivate::ExtraDataTags)
+
 /*
     Key filters can be installed on a QQuickItem, but not removed.  Currently they
     are only used by attached objects (which are only destroyed on Item
@@ -947,7 +956,7 @@ private:
 
 Qt::MouseButtons QQuickItemPrivate::acceptedMouseButtons() const
 {
-    return ((extra.flag() ? Qt::LeftButton : Qt::MouseButton(0)) |
+    return ((extra.tag().testFlag(LeftMouseButtonAccepted) ? Qt::LeftButton : Qt::MouseButton(0)) |
             (extra.isAllocated() ? extra->acceptedMouseButtons : Qt::MouseButtons{}));
 }