6 files changed, 325 insertions, 440 deletions
diff --git a/src/corelib/kernel/kernel.pri b/src/corelib/kernel/kernel.pri
index fc48ef430e..a493260c50 100644
--- a/src/corelib/kernel/kernel.pri
+++ b/src/corelib/kernel/kernel.pri
@@ -46,8 +46,7 @@ HEADERS += \
         kernel/qtestsupport_core.h \
         kernel/qproperty.h \
         kernel/qpropertyprivate.h \
-        kernel/qproperty_p.h \
-        kernel/qpropertybinding_p.h
+        kernel/qproperty_p.h
 
 SOURCES += \
         kernel/qabstracteventdispatcher.cpp \
@@ -77,7 +76,6 @@ SOURCES += \
         kernel/qsystemerror.cpp \
         kernel/qtestsupport_core.cpp \
         kernel/qproperty.cpp \
-        kernel/qpropertybinding.cpp
 
 win32 {
         SOURCES += \
diff --git a/src/corelib/kernel/qproperty.cpp b/src/corelib/kernel/qproperty.cpp
index 9374ce3a74..3bac73909a 100644
--- a/src/corelib/kernel/qproperty.cpp
+++ b/src/corelib/kernel/qproperty.cpp
@@ -39,7 +39,6 @@
 
 #include "qproperty.h"
 #include "qproperty_p.h"
-#include "qpropertybinding_p.h"
 
 #include <qscopedvaluerollback.h>
 
@@ -47,6 +46,166 @@ QT_BEGIN_NAMESPACE
 
 using namespace QtPrivate;
 
+void QPropertyBasePointer::addObserver(QPropertyObserver *observer)
+{
+    if (auto *binding = bindingPtr()) {
+        observer->prev = &binding->firstObserver.ptr;
+        observer->next = binding->firstObserver.ptr;
+        if (observer->next)
+            observer->next->prev = &observer->next;
+        binding->firstObserver.ptr = observer;
+    } else {
+        auto firstObserver = reinterpret_cast<QPropertyObserver*>(ptr->d_ptr & ~QPropertyBase::FlagMask);
+        observer->prev = reinterpret_cast<QPropertyObserver**>(&ptr->d_ptr);
+        observer->next = firstObserver;
+        if (observer->next)
+            observer->next->prev = &observer->next;
+    }
+    setFirstObserver(observer);
+}
+
+QPropertyBindingPrivate::~QPropertyBindingPrivate()
+{
+    if (firstObserver)
+        firstObserver.unlink();
+    if (!hasStaticObserver)
+        inlineDependencyObservers.~ObserverArray(); // Explicit because of union.
+}
+
+void QPropertyBindingPrivate::unlinkAndDeref()
+{
+    propertyDataPtr = nullptr;
+    if (!ref.deref())
+        delete this;
+}
+
+void QPropertyBindingPrivate::markDirtyAndNotifyObservers()
+{
+    if (dirty)
+        return;
+    dirty = true;
+    if (firstObserver)
+        firstObserver.notify(this, propertyDataPtr);
+    if (hasStaticObserver) {
+        if (isBool) {
+            auto propertyPtr = reinterpret_cast<QPropertyBase *>(propertyDataPtr);
+            bool oldValue = propertyPtr->extraBit();
+            staticObserverCallback(staticObserver, &oldValue);
+        } else {
+            staticObserverCallback(staticObserver, propertyDataPtr);
+        }
+    }
+}
+
+bool QPropertyBindingPrivate::evaluateIfDirtyAndReturnTrueIfValueChanged()
+{
+    if (!dirty)
+        return false;
+
+    if (updating) {
+        error = QPropertyBindingError(QPropertyBindingError::BindingLoop);
+        return false;
+    }
+
+    /*
+     * Evaluating the binding might lead to the binding being broken. This can
+     * cause ref to reach zero at the end of the function.  However, the
+     * updateGuard's destructor will then still trigger, trying to set the
+     * updating bool to its old value
+     * To prevent this, we create a QPropertyBindingPrivatePtr which ensures
+     * that the object is still alive when updateGuard's dtor runs.
+     */
+    QPropertyBindingPrivatePtr keepAlive {this};
+    QScopedValueRollback<bool> updateGuard(updating, true);
+
+    BindingEvaluationState evaluationFrame(this);
+
+    bool changed = false;
+
+    if (hasStaticObserver && staticGuardCallback) {
+        if (isBool) {
+            auto propertyPtr = reinterpret_cast<QPropertyBase *>(propertyDataPtr);
+            bool newValue = propertyPtr->extraBit();
+            changed = staticGuardCallback(metaType, &newValue, evaluationFunction, staticObserver);
+            if (changed && !error.hasError())
+                propertyPtr->setExtraBit(newValue);
+        } else {
+            changed = staticGuardCallback(metaType, propertyDataPtr, evaluationFunction, staticObserver);
+        }
+    } else {
+        if (isBool) {
+            auto propertyPtr = reinterpret_cast<QPropertyBase *>(propertyDataPtr);
+            bool newValue = propertyPtr->extraBit();
+            changed = evaluationFunction(metaType, &newValue);
+            if (changed && !error.hasError())
+                propertyPtr->setExtraBit(newValue);
+        } else {
+            changed = evaluationFunction(metaType, propertyDataPtr);
+        }
+    }
+
+    dirty = false;
+    return changed;
+}
+
+QUntypedPropertyBinding::QUntypedPropertyBinding() = default;
+
+QUntypedPropertyBinding::QUntypedPropertyBinding(const QMetaType &metaType, QUntypedPropertyBinding::BindingEvaluationFunction function,
+                                                 const QPropertyBindingSourceLocation &location)
+{
+    d = new QPropertyBindingPrivate(metaType, std::move(function), std::move(location));
+}
+
+QUntypedPropertyBinding::QUntypedPropertyBinding(QUntypedPropertyBinding &&other)
+    : d(std::move(other.d))
+{
+}
+
+QUntypedPropertyBinding::QUntypedPropertyBinding(const QUntypedPropertyBinding &other)
+    : d(other.d)
+{
+}
+
+QUntypedPropertyBinding &QUntypedPropertyBinding::operator=(const QUntypedPropertyBinding &other)
+{
+    d = other.d;
+    return *this;
+}
+
+QUntypedPropertyBinding &QUntypedPropertyBinding::operator=(QUntypedPropertyBinding &&other)
+{
+    d = std::move(other.d);
+    return *this;
+}
+
+QUntypedPropertyBinding::QUntypedPropertyBinding(QPropertyBindingPrivate *priv)
+    : d(priv)
+{
+}
+
+QUntypedPropertyBinding::~QUntypedPropertyBinding()
+{
+}
+
+bool QUntypedPropertyBinding::isNull() const
+{
+    return !d;
+}
+
+QPropertyBindingError QUntypedPropertyBinding::error() const
+{
+    if (!d)
+        return QPropertyBindingError();
+    return d->bindingError();
+}
+
+QMetaType QUntypedPropertyBinding::valueMetaType() const
+{
+    if (!d)
+        return QMetaType();
+    return d->valueMetaType();
+}
+
 QPropertyBase::QPropertyBase(QPropertyBase &&other, void *propertyDataPtr)
 {
     std::swap(d_ptr, other.d_ptr);
@@ -141,53 +300,6 @@ QPropertyBindingPrivate *QPropertyBase::binding()
     return nullptr;
 }
 
-QPropertyBindingPrivate *QPropertyBasePointer::bindingPtr() const
-{
-    if (ptr->d_ptr & QPropertyBase::BindingBit)
-        return reinterpret_cast<QPropertyBindingPrivate*>(ptr->d_ptr & ~QPropertyBase::FlagMask);
-    return nullptr;
-}
-
-void QPropertyBasePointer::setObservers(QPropertyObserver *observer)
-{
-    observer->prev = reinterpret_cast<QPropertyObserver**>(&(ptr->d_ptr));
-    ptr->d_ptr = (reinterpret_cast<quintptr>(observer) & ~QPropertyBase::FlagMask);
-}
-
-void QPropertyBasePointer::addObserver(QPropertyObserver *observer)
-{
-    if (auto *binding = bindingPtr()) {
-        observer->prev = &binding->firstObserver.ptr;
-        observer->next = binding->firstObserver.ptr;
-        if (observer->next)
-            observer->next->prev = &observer->next;
-        binding->firstObserver.ptr = observer;
-    } else {
-        auto firstObserver = reinterpret_cast<QPropertyObserver*>(ptr->d_ptr & ~QPropertyBase::FlagMask);
-        observer->prev = reinterpret_cast<QPropertyObserver**>(&ptr->d_ptr);
-        observer->next = firstObserver;
-        if (observer->next)
-            observer->next->prev = &observer->next;
-    }
-    setFirstObserver(observer);
-}
-
-void QPropertyBasePointer::setFirstObserver(QPropertyObserver *observer)
-{
-    if (auto *binding = bindingPtr()) {
-        binding->firstObserver.ptr = observer;
-        return;
-    }
-    ptr->d_ptr = reinterpret_cast<quintptr>(observer) | (ptr->d_ptr & QPropertyBase::FlagMask);
-}
-
-QPropertyObserverPointer QPropertyBasePointer::firstObserver() const
-{
-    if (auto *binding = bindingPtr())
-        return binding->firstObserver;
-    return {reinterpret_cast<QPropertyObserver*>(ptr->d_ptr & ~QPropertyBase::FlagMask)};
-}
-
 static thread_local BindingEvaluationState *currentBindingEvaluationState = nullptr;
 
 BindingEvaluationState::BindingEvaluationState(QPropertyBindingPrivate *binding)
diff --git a/src/corelib/kernel/qproperty_p.h b/src/corelib/kernel/qproperty_p.h
index 7b9d7c207f..159c652657 100644
--- a/src/corelib/kernel/qproperty_p.h
+++ b/src/corelib/kernel/qproperty_p.h
@@ -52,20 +52,35 @@
 //
 
 #include <qglobal.h>
+#include <qproperty.h>
+
 #include <qvarlengtharray.h>
+#include <qscopedpointer.h>
+#include <vector>
 
-#include "qproperty.h"
 
 QT_BEGIN_NAMESPACE
 
+// Keep all classes related to QProperty in one compilation unit. Performance of this code is crucial and
+// we need to allow the compiler to inline where it makes sense.
+
 // This is a helper "namespace"
 struct Q_AUTOTEST_EXPORT QPropertyBasePointer
 {
     const QtPrivate::QPropertyBase *ptr = nullptr;
 
-    QPropertyBindingPrivate *bindingPtr() const;
+    QPropertyBindingPrivate *bindingPtr() const
+    {
+        if (ptr->d_ptr & QtPrivate::QPropertyBase::BindingBit)
+            return reinterpret_cast<QPropertyBindingPrivate*>(ptr->d_ptr & ~QtPrivate::QPropertyBase::FlagMask);
+        return nullptr;
+    }
 
-    void setObservers(QPropertyObserver *observer);
+    void setObservers(QPropertyObserver *observer)
+    {
+        observer->prev = reinterpret_cast<QPropertyObserver**>(&(ptr->d_ptr));
+        ptr->d_ptr = (reinterpret_cast<quintptr>(observer) & ~QtPrivate::QPropertyBase::FlagMask);
+    }
     void addObserver(QPropertyObserver *observer);
     void setFirstObserver(QPropertyObserver *observer);
     QPropertyObserverPointer firstObserver() const;
@@ -114,6 +129,150 @@ struct BindingEvaluationState
     BindingEvaluationState **currentState = nullptr;
 };
 
+class Q_CORE_EXPORT QPropertyBindingPrivate : public QSharedData
+{
+private:
+    friend struct QPropertyBasePointer;
+
+    using ObserverArray = std::array<QPropertyObserver, 4>;
+
+    // QSharedData is 4 bytes. Use the padding for the bools as we need 8 byte alignment below.
+    bool dirty = false;
+    bool updating = false;
+    bool hasStaticObserver = false;
+    bool isBool = false;
+
+    QUntypedPropertyBinding::BindingEvaluationFunction evaluationFunction;
+
+    QPropertyObserverPointer firstObserver;
+    union {
+        ObserverArray inlineDependencyObservers;
+        struct {
+            void *staticObserver;
+            QtPrivate::QPropertyObserverCallback staticObserverCallback;
+            QtPrivate::QPropertyGuardFunction staticGuardCallback;
+        };
+    };
+    QScopedPointer<std::vector<QPropertyObserver>> heapObservers;
+
+    void *propertyDataPtr = nullptr;
+
+    QPropertyBindingSourceLocation location;
+    QPropertyBindingError error;
+
+    QMetaType metaType;
+
+public:
+    // public because the auto-tests access it, too.
+    size_t dependencyObserverCount = 0;
+
+    QPropertyBindingPrivate(const QMetaType &metaType, QUntypedPropertyBinding::BindingEvaluationFunction evaluationFunction,
+                            const QPropertyBindingSourceLocation &location)
+        : isBool(metaType.id() == QMetaType::Bool)
+        , evaluationFunction(std::move(evaluationFunction))
+        , inlineDependencyObservers() // Explicit initialization required because of union
+        , location(location)
+        , metaType(metaType)
+    {}
+    virtual ~QPropertyBindingPrivate();
+
+    void setDirty(bool d) { dirty = d; }
+    void setProperty(void *propertyPtr) { propertyDataPtr = propertyPtr; }
+    void setStaticObserver(void *observer, QtPrivate::QPropertyObserverCallback callback,
+                           QtPrivate::QPropertyGuardFunction guardCallback)
+    {
+        if (observer) {
+            if (!hasStaticObserver) {
+                if (dependencyObserverCount > 0) {
+                    if (!heapObservers)
+                        heapObservers.reset(new std::vector<QPropertyObserver>());
+                    for (size_t i = 0, end = qMin(dependencyObserverCount, inlineDependencyObservers.size()); i < end; ++i)
+                        heapObservers->push_back(std::move(inlineDependencyObservers[i]));
+                }
+                inlineDependencyObservers.~ObserverArray();
+            }
+
+            hasStaticObserver = true;
+            staticObserver = observer;
+            staticObserverCallback = callback;
+            staticGuardCallback = guardCallback;
+        } else if (hasStaticObserver) {
+            hasStaticObserver = false;
+            new (&inlineDependencyObservers) ObserverArray();
+            for (size_t i = 0, end = qMin(dependencyObserverCount, inlineDependencyObservers.size()); i < end; ++i) {
+                inlineDependencyObservers[i] = std::move(heapObservers->back());
+                heapObservers->pop_back();
+            }
+        }
+    }
+    void prependObserver(QPropertyObserverPointer observer) {
+        observer.ptr->prev = const_cast<QPropertyObserver **>(&firstObserver.ptr);
+        firstObserver = observer;
+    }
+
+    QPropertyObserverPointer takeObservers()
+    {
+        auto observers = firstObserver;
+        firstObserver.ptr = nullptr;
+        return observers;
+    }
+
+    void clearDependencyObservers() {
+        if (!hasStaticObserver) {
+            for (size_t i = 0; i < qMin(dependencyObserverCount, inlineDependencyObservers.size()); ++i) {
+                QPropertyObserverPointer p{&inlineDependencyObservers[i]};
+                p.unlink();
+            }
+        }
+        if (heapObservers)
+            heapObservers->clear();
+        dependencyObserverCount = 0;
+    }
+    QPropertyObserverPointer allocateDependencyObserver() {
+        if (!hasStaticObserver && dependencyObserverCount < inlineDependencyObservers.size()) {
+            ++dependencyObserverCount;
+            return {&inlineDependencyObservers[dependencyObserverCount - 1]};
+        }
+        ++dependencyObserverCount;
+        if (!heapObservers)
+            heapObservers.reset(new std::vector<QPropertyObserver>());
+        return {&heapObservers->emplace_back()};
+    }
+
+    QPropertyBindingSourceLocation sourceLocation() const { return location; }
+    QPropertyBindingError bindingError() const { return error; }
+    QMetaType valueMetaType() const { return metaType; }
+
+    void unlinkAndDeref();
+
+    void markDirtyAndNotifyObservers();
+    bool evaluateIfDirtyAndReturnTrueIfValueChanged();
+
+    static QPropertyBindingPrivate *get(const QUntypedPropertyBinding &binding)
+    { return binding.d.data(); }
+
+    void setError(QPropertyBindingError &&e)
+    { error = std::move(e); }
+
+    static QPropertyBindingPrivate *currentlyEvaluatingBinding();
+};
+
+inline void QPropertyBasePointer::setFirstObserver(QPropertyObserver *observer)
+{
+    if (auto *binding = bindingPtr()) {
+        binding->firstObserver.ptr = observer;
+        return;
+    }
+    ptr->d_ptr = reinterpret_cast<quintptr>(observer) | (ptr->d_ptr & QtPrivate::QPropertyBase::FlagMask);
+}
+
+inline QPropertyObserverPointer QPropertyBasePointer::firstObserver() const
+{
+    if (auto *binding = bindingPtr())
+        return binding->firstObserver;
+    return {reinterpret_cast<QPropertyObserver*>(ptr->d_ptr & ~QtPrivate::QPropertyBase::FlagMask)};
+}
+
 QT_END_NAMESPACE
 
 #endif // QPROPERTY_P_H
diff --git a/src/corelib/kernel/qpropertybinding.cpp b/src/corelib/kernel/qpropertybinding.cpp
deleted file mode 100644
index 63800c4f7d..0000000000
--- a/src/corelib/kernel/qpropertybinding.cpp
+++ /dev/null
@@ -1,192 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2020 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the QtCore module of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 3 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL3 included in the
-** packaging of this file. Please review the following information to
-** ensure the GNU Lesser General Public License version 3 requirements
-** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 2.0 or (at your option) the GNU General
-** Public license version 3 or any later version approved by the KDE Free
-** Qt Foundation. The licenses are as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
-** included in the packaging of this file. Please review the following
-** information to ensure the GNU General Public License requirements will
-** be met: https://www.gnu.org/licenses/gpl-2.0.html and
-** https://www.gnu.org/licenses/gpl-3.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#include "qpropertybinding_p.h"
-#include "qproperty_p.h"
-
-#include <QScopedValueRollback>
-#include <QVariant>
-
-QT_BEGIN_NAMESPACE
-
-using namespace QtPrivate;
-
-QPropertyBindingPrivate::~QPropertyBindingPrivate()
-{
-    if (firstObserver)
-        firstObserver.unlink();
-    if (!hasStaticObserver)
-        inlineDependencyObservers.~ObserverArray(); // Explicit because of union.
-}
-
-void QPropertyBindingPrivate::unlinkAndDeref()
-{
-    propertyDataPtr = nullptr;
-    if (!ref.deref())
-        delete this;
-}
-
-void QPropertyBindingPrivate::markDirtyAndNotifyObservers()
-{
-    if (dirty)
-        return;
-    dirty = true;
-    if (firstObserver)
-        firstObserver.notify(this, propertyDataPtr);
-    if (hasStaticObserver) {
-        if (isBool) {
-            auto propertyPtr = reinterpret_cast<QPropertyBase *>(propertyDataPtr);
-            bool oldValue = propertyPtr->extraBit();
-            staticObserverCallback(staticObserver, &oldValue);
-        } else {
-            staticObserverCallback(staticObserver, propertyDataPtr);
-        }
-    }
-}
-
-bool QPropertyBindingPrivate::evaluateIfDirtyAndReturnTrueIfValueChanged()
-{
-    if (!dirty)
-        return false;
-
-    if (updating) {
-        error = QPropertyBindingError(QPropertyBindingError::BindingLoop);
-        return false;
-    }
-
-    /*
-     * Evaluating the binding might lead to the binding being broken. This can
-     * cause ref to reach zero at the end of the function.  However, the
-     * updateGuard's destructor will then still trigger, trying to set the
-     * updating bool to its old value
-     * To prevent this, we create a QPropertyBindingPrivatePtr which ensures
-     * that the object is still alive when updateGuard's dtor runs.
-     */
-    QPropertyBindingPrivatePtr keepAlive {this};
-    QScopedValueRollback<bool> updateGuard(updating, true);
-
-    BindingEvaluationState evaluationFrame(this);
-
-    bool changed = false;
-
-    if (hasStaticObserver && staticGuardCallback) {
-        if (isBool) {
-            auto propertyPtr = reinterpret_cast<QPropertyBase *>(propertyDataPtr);
-            bool newValue = propertyPtr->extraBit();
-            changed = staticGuardCallback(metaType, &newValue, evaluationFunction, staticObserver);
-            if (changed && !error.hasError())
-                propertyPtr->setExtraBit(newValue);
-        } else {
-            changed = staticGuardCallback(metaType, propertyDataPtr, evaluationFunction, staticObserver);
-        }
-    } else {
-        if (isBool) {
-            auto propertyPtr = reinterpret_cast<QPropertyBase *>(propertyDataPtr);
-            bool newValue = propertyPtr->extraBit();
-            changed = evaluationFunction(metaType, &newValue);
-            if (changed && !error.hasError())
-                propertyPtr->setExtraBit(newValue);
-        } else {
-            changed = evaluationFunction(metaType, propertyDataPtr);
-        }
-    }
-
-    dirty = false;
-    return changed;
-}
-
-QUntypedPropertyBinding::QUntypedPropertyBinding() = default;
-
-QUntypedPropertyBinding::QUntypedPropertyBinding(const QMetaType &metaType, QUntypedPropertyBinding::BindingEvaluationFunction function,
-                                                 const QPropertyBindingSourceLocation &location)
-{
-    d = new QPropertyBindingPrivate(metaType, std::move(function), std::move(location));
-}
-
-QUntypedPropertyBinding::QUntypedPropertyBinding(QUntypedPropertyBinding &&other)
-    : d(std::move(other.d))
-{
-}
-
-QUntypedPropertyBinding::QUntypedPropertyBinding(const QUntypedPropertyBinding &other)
-    : d(other.d)
-{
-}
-
-QUntypedPropertyBinding &QUntypedPropertyBinding::operator=(const QUntypedPropertyBinding &other)
-{
-    d = other.d;
-    return *this;
-}
-
-QUntypedPropertyBinding &QUntypedPropertyBinding::operator=(QUntypedPropertyBinding &&other)
-{
-    d = std::move(other.d);
-    return *this;
-}
-
-QUntypedPropertyBinding::QUntypedPropertyBinding(QPropertyBindingPrivate *priv)
-    : d(priv)
-{
-}
-
-QUntypedPropertyBinding::~QUntypedPropertyBinding()
-{
-}
-
-bool QUntypedPropertyBinding::isNull() const
-{
-    return !d;
-}
-
-QPropertyBindingError QUntypedPropertyBinding::error() const
-{
-    if (!d)
-        return QPropertyBindingError();
-    return d->bindingError();
-}
-
-QMetaType QUntypedPropertyBinding::valueMetaType() const
-{
-    if (!d)
-        return QMetaType();
-    return d->valueMetaType();
-}
-
-QT_END_NAMESPACE
diff --git a/src/corelib/kernel/qpropertybinding_p.h b/src/corelib/kernel/qpropertybinding_p.h
deleted file mode 100644
index 1aa2cd864c..0000000000
--- a/src/corelib/kernel/qpropertybinding_p.h
+++ /dev/null
@@ -1,194 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2020 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the QtCore module of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 3 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPL3 included in the
-** packaging of this file. Please review the following information to
-** ensure the GNU Lesser General Public License version 3 requirements
-** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 2.0 or (at your option) the GNU General
-** Public license version 3 or any later version approved by the KDE Free
-** Qt Foundation. The licenses are as published by the Free Software
-** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
-** included in the packaging of this file. Please review the following
-** information to ensure the GNU General Public License requirements will
-** be met: https://www.gnu.org/licenses/gpl-2.0.html and
-** https://www.gnu.org/licenses/gpl-3.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#ifndef QPROPERTYBINDING_P_H
-#define QPROPERTYBINDING_P_H
-
-//
-//  W A R N I N G
-//  -------------
-//
-// This file is not part of the Qt API.  It exists for the convenience
-// of qapplication_*.cpp, qwidget*.cpp and qfiledialog.cpp.  This header
-// file may change from version to version without notice, or even be removed.
-//
-// We mean it.
-//
-
-#include <QtCore/qglobal.h>
-#include <QtCore/qshareddata.h>
-#include <QtCore/qscopedpointer.h>
-#include <vector>
-#include <functional>
-
-#include "qproperty_p.h"
-
-QT_BEGIN_NAMESPACE
-
-class Q_CORE_EXPORT QPropertyBindingPrivate : public QSharedData
-{
-private:
-    friend struct QPropertyBasePointer;
-
-    using ObserverArray = std::array<QPropertyObserver, 4>;
-
-    // QSharedData is 4 bytes. Use the padding for the bools as we need 8 byte alignment below.
-    bool dirty = false;
-    bool updating = false;
-    bool hasStaticObserver = false;
-    bool isBool = false;
-
-    QUntypedPropertyBinding::BindingEvaluationFunction evaluationFunction;
-
-    QPropertyObserverPointer firstObserver;
-    union {
-        ObserverArray inlineDependencyObservers;
-        struct {
-            void *staticObserver;
-            QtPrivate::QPropertyObserverCallback staticObserverCallback;
-            QtPrivate::QPropertyGuardFunction staticGuardCallback;
-        };
-    };
-    QScopedPointer<std::vector<QPropertyObserver>> heapObservers;
-
-    void *propertyDataPtr = nullptr;
-
-    QPropertyBindingSourceLocation location;
-    QPropertyBindingError error;
-
-    QMetaType metaType;
-
-public:
-    // public because the auto-tests access it, too.
-    size_t dependencyObserverCount = 0;
-
-    QPropertyBindingPrivate(const QMetaType &metaType, QUntypedPropertyBinding::BindingEvaluationFunction evaluationFunction,
-                            const QPropertyBindingSourceLocation &location)
-        : isBool(metaType.id() == QMetaType::Bool)
-        , evaluationFunction(std::move(evaluationFunction))
-        , inlineDependencyObservers() // Explicit initialization required because of union
-        , location(location)
-        , metaType(metaType)
-    {}
-    virtual ~QPropertyBindingPrivate();
-
-    void setDirty(bool d) { dirty = d; }
-    void setProperty(void *propertyPtr) { propertyDataPtr = propertyPtr; }
-    void setStaticObserver(void *observer, QtPrivate::QPropertyObserverCallback callback,
-                           QtPrivate::QPropertyGuardFunction guardCallback)
-    {
-        if (observer) {
-            if (!hasStaticObserver) {
-                if (dependencyObserverCount > 0) {
-                    if (!heapObservers)
-                        heapObservers.reset(new std::vector<QPropertyObserver>());
-                    for (int i = 0, end = qMin(dependencyObserverCount, inlineDependencyObservers.size()); i < end; ++i)
-                        heapObservers->push_back(std::move(inlineDependencyObservers[i]));
-                }
-                inlineDependencyObservers.~ObserverArray();
-            }
-
-            hasStaticObserver = true;
-            staticObserver = observer;
-            staticObserverCallback = callback;
-            staticGuardCallback = guardCallback;
-        } else if (hasStaticObserver) {
-            hasStaticObserver = false;
-            new (&inlineDependencyObservers) ObserverArray();
-            for (int i = 0, end = qMin(dependencyObserverCount, inlineDependencyObservers.size()); i < end; ++i) {
-                inlineDependencyObservers[i] = std::move(heapObservers->back());
-                heapObservers->pop_back();
-            }
-        }
-    }
-    void prependObserver(QPropertyObserverPointer observer) {
-        observer.ptr->prev = const_cast<QPropertyObserver **>(&firstObserver.ptr);
-        firstObserver = observer;
-    }
-
-    QPropertyObserverPointer takeObservers()
-    {
-        auto observers = firstObserver;
-        firstObserver.ptr = nullptr;
-        return observers;
-    }
-
-    void clearDependencyObservers() {
-        if (!hasStaticObserver) {
-            for (size_t i = 0; i < qMin(dependencyObserverCount, inlineDependencyObservers.size()); ++i) {
-                QPropertyObserverPointer p{&inlineDependencyObservers[i]};
-                p.unlink();
-            }
-        }
-        if (heapObservers)
-            heapObservers->clear();
-        dependencyObserverCount = 0;
-    }
-    QPropertyObserverPointer allocateDependencyObserver() {
-        if (!hasStaticObserver && dependencyObserverCount < inlineDependencyObservers.size()) {
-            ++dependencyObserverCount;
-            return {&inlineDependencyObservers[dependencyObserverCount - 1]};
-        }
-        ++dependencyObserverCount;
-        if (!heapObservers)
-            heapObservers.reset(new std::vector<QPropertyObserver>());
-        return {&heapObservers->emplace_back()};
-    }
-
-    QPropertyBindingSourceLocation sourceLocation() const { return location; }
-    QPropertyBindingError bindingError() const { return error; }
-    QMetaType valueMetaType() const { return metaType; }
-
-    void unlinkAndDeref();
-
-    void markDirtyAndNotifyObservers();
-    bool evaluateIfDirtyAndReturnTrueIfValueChanged();
-
-    static QPropertyBindingPrivate *get(const QUntypedPropertyBinding &binding)
-    { return binding.d.data(); }
-
-    void setError(QPropertyBindingError &&e)
-    { error = std::move(e); }
-
-    static QPropertyBindingPrivate *currentlyEvaluatingBinding();
-};
-
-QT_END_NAMESPACE
-
-#endif // QPROPERTYBINDING_P_H
diff --git a/src/corelib/kernel/qpropertyprivate.h b/src/corelib/kernel/qpropertyprivate.h
index 91d9204996..ad5ed59e88 100644
--- a/src/corelib/kernel/qpropertyprivate.h
+++ b/src/corelib/kernel/qpropertyprivate.h
@@ -55,6 +55,8 @@
 #include <QtCore/QExplicitlySharedDataPointer>
 #include <QtCore/qtaggedpointer.h>
 
+#include <functional>
+
 QT_BEGIN_NAMESPACE
 
 class QUntypedPropertyBinding;