Move all the QProperty related code into one compilation unit

And mark some methods as inline.

Performance is critical for our new property system. Compiling
it in one unit makes it possible for the compiler to do a much
better job at inlining and generating optimized code.

Improves performance of binding evaluations by another 20%.

Change-Id: I5a2aa93c74d2b68418b0a9d2e34d8199bb71e3ad
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

8 files changed, 325 insertions, 442 deletions

diff --git a/src/corelib/CMakeLists.txt b/src/corelib/CMakeLists.txt
index bb697f23f4..9deda274b7 100644
--- a/src/corelib/CMakeLists.txt
+++ b/src/corelib/CMakeLists.txt
@@ -111,7 +111,6 @@ qt_add_module(Core
         kernel/qobjectdefs_impl.h
         kernel/qpointer.cpp kernel/qpointer.h
         kernel/qproperty.cpp kernel/qproperty.h kernel/qproperty_p.h
-        kernel/qpropertybinding.cpp kernel/qpropertybinding_p.h
         kernel/qpropertyprivate.h
         kernel/qsharedmemory.cpp kernel/qsharedmemory.h kernel/qsharedmemory_p.h
         kernel/qsignalmapper.cpp kernel/qsignalmapper.h
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;
diff --git a/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp b/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp
index bac25e02b0..5f17bcb2b7 100644
--- a/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp
+++ b/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp
@@ -30,7 +30,6 @@
 #include <qtest.h>
 #include <qproperty.h>
 #include <private/qproperty_p.h>
-#include <private/qpropertybinding_p.h>
 
 using namespace QtPrivate;