Remove lazy binding evaluation

Too much of the existing code in Qt requires eager evaluation without
large scale modifications. Combined with the fact that supporting both
eager and lazy evaluation has a high maintenance burden, keeping lazy
evaluation, at least in its current state, is not worth it.

This does not diminish other benefits of the new property system, which
include
- a C++ API to setup and modify bindings and
- faster execution compared to QML's existing bindings and the ability
  to use them without having a QML engine.

We do no longer benefit from doing less work thanks to laziness. A later
commit will introduce grouping support to recapture some of this
benefit.

[ChangeLog][Import Behavior Change][QProperty] QProperty uses always
eager evaluation now when a dependency in a binding changes.

Change-Id: I34694fd5c7bcb1d31a0052d2e3da8b68d016671b
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Andreas Buhr <andreas.buhr@qt.io>
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>

6 files changed, 70 insertions, 162 deletions

diff --git a/src/corelib/doc/src/objectmodel/bindableproperties.qdoc b/src/corelib/doc/src/objectmodel/bindableproperties.qdoc
index 8b50c65d7c..1bb20935d0 100644
--- a/src/corelib/doc/src/objectmodel/bindableproperties.qdoc
+++ b/src/corelib/doc/src/objectmodel/bindableproperties.qdoc
@@ -50,8 +50,7 @@
     The binding expression computes the value by reading other QProperty values.
     Behind the scenes this dependency is tracked. Whenever a change in any property's
     dependency is detected, the binding expression is re-evaluated and the new
-    result is applied to the property. This happens lazily, by marking the binding
-    as dirty and evaluating it only when the property's value is requested. For example:
+    result is applied to the property. For example:
 
     \code
     QProperty<QString> firstname("John");
@@ -63,20 +62,19 @@
 
     qDebug() << fullname.value(); // Prints "John Smith age: 41"
 
-    firstname = "Emma"; // Marks binding expression as dirty
+    firstname = "Emma"; // Triggers binding reevaluation
 
-    qDebug() << fullname.value(); // Re-evaluates the binding expression and prints "Emma Smith age: 41"
+    qDebug() << fullname.value(); // Prints the new value "Emma Smith age: 41"
 
     // Birthday is coming up
-    age.setValue(age.value() + 1);
+    age.setValue(age.value() + 1); // Triggers re-evaluation
 
-    qDebug() << fullname.value(); // Re-evaluates the binding expression and prints "Emma Smith age: 42"
+    qDebug() << fullname.value(); // Prints "Emma Smith age: 42"
     \endcode
 
     When a new value is assigned to the \c firstname property, the binding
-    expression for \c fullname is marked as dirty. So when the last \c qDebug() statement
-    tries to read the name value of the \c fullname property, the expression is
-    evaluated again, \c firstname() will be called again and return the new value.
+    expression for \c fullname is reevaluated. So when the last \c qDebug() statement
+    tries to read the name value of the \c fullname property, the new value is returned.
 
     Since bindings are C++ functions, they may do anything that's possible
     in C++. This includes calling other functions. If those functions access values
diff --git a/src/corelib/kernel/qproperty.cpp b/src/corelib/kernel/qproperty.cpp
index d03991eac1..ad25492283 100644
--- a/src/corelib/kernel/qproperty.cpp
+++ b/src/corelib/kernel/qproperty.cpp
@@ -98,43 +98,16 @@ void QPropertyBindingPrivate::unlinkAndDeref()
         destroyAndFreeMemory(this);
 }
 
-void QPropertyBindingPrivate::markDirtyAndNotifyObservers()
+void QPropertyBindingPrivate::evaluate()
 {
-    if (eagerlyUpdating) {
+    if (updating) {
         error = QPropertyBindingError(QPropertyBindingError::BindingLoop);
         if (isQQmlPropertyBinding)
             errorCallBack(this);
         return;
     }
-    if (dirty)
-        return;
-    dirty = true;
-
-    eagerlyUpdating = true;
-    QScopeGuard guard([&](){eagerlyUpdating = false;});
-    bool knownToHaveChanged = false;
-    if (requiresEagerEvaluation()) {
-        // these are compat properties that we will need to evaluate eagerly
-        if (!evaluateIfDirtyAndReturnTrueIfValueChanged(propertyDataPtr))
-            return;
-        knownToHaveChanged = true;
-    }
-    if (firstObserver)
-        firstObserver.notify(this, propertyDataPtr, knownToHaveChanged);
-    if (hasStaticObserver)
-        staticObserverCallback(propertyDataPtr);
-}
-
-bool QPropertyBindingPrivate::evaluateIfDirtyAndReturnTrueIfValueChanged_helper(const QUntypedPropertyData *data, QBindingStatus *status)
-{
-    Q_ASSERT(dirty);
 
-    if (updating) {
-        error = QPropertyBindingError(QPropertyBindingError::BindingLoop);
-        if (isQQmlPropertyBinding)
-            errorCallBack(this);
-        return false;
-    }
+    QScopedValueRollback<bool> updateGuard(updating, true);
 
     /*
      * Evaluating the binding might lead to the binding being broken. This can
@@ -145,23 +118,26 @@ bool QPropertyBindingPrivate::evaluateIfDirtyAndReturnTrueIfValueChanged_helper(
      * that the object is still alive when updateGuard's dtor runs.
      */
     QPropertyBindingPrivatePtr keepAlive {this};
-    QScopedValueRollback<bool> updateGuard(updating, true);
-
-    BindingEvaluationState evaluationFrame(this, status);
 
-    bool changed = false;
-
-    Q_ASSERT(propertyDataPtr == data);
-    QUntypedPropertyData *mutable_data = const_cast<QUntypedPropertyData *>(data);
+    BindingEvaluationState evaluationFrame(this);
 
+    bool changed;
+    auto bindingFunctor =  reinterpret_cast<std::byte *>(this) +
+        QPropertyBindingPrivate::getSizeEnsuringAlignment();
     if (hasBindingWrapper) {
-        changed = staticBindingWrapper(metaType, mutable_data, {vtable, reinterpret_cast<std::byte *>(this)+QPropertyBindingPrivate::getSizeEnsuringAlignment()});
+        changed = staticBindingWrapper(metaType, propertyDataPtr,
+                {vtable, bindingFunctor});
     } else {
-        changed = vtable->call(metaType, mutable_data, reinterpret_cast<std::byte *>(this)+ QPropertyBindingPrivate::getSizeEnsuringAlignment());
+        changed = vtable->call(metaType, propertyDataPtr, bindingFunctor);
     }
+    if (!changed)
+        return;
 
-    dirty = false;
-    return changed;
+    // notify dependent bindings and emit changed signal
+    if (firstObserver)
+        firstObserver.notify(propertyDataPtr);
+    if (hasStaticObserver)
+        staticObserverCallback(propertyDataPtr);
 }
 
 QUntypedPropertyBinding::QUntypedPropertyBinding() = default;
@@ -250,7 +226,7 @@ QUntypedPropertyBinding QPropertyBindingData::setBinding(const QUntypedPropertyB
     if (auto *existingBinding = d.bindingPtr()) {
         if (existingBinding == newBinding.data())
             return QUntypedPropertyBinding(static_cast<QPropertyBindingPrivate *>(oldBinding.data()));
-        if (existingBinding->isEagerlyUpdating()) {
+        if (existingBinding->isUpdating()) {
             existingBinding->setError({QPropertyBindingError::BindingLoop, QStringLiteral("Binding set during binding evaluation!")});
             return QUntypedPropertyBinding(static_cast<QPropertyBindingPrivate *>(oldBinding.data()));
         }
@@ -267,18 +243,12 @@ QUntypedPropertyBinding QPropertyBindingData::setBinding(const QUntypedPropertyB
         d_ptr = reinterpret_cast<quintptr>(newBinding.data());
         d_ptr |= BindingBit;
         auto newBindingRaw = static_cast<QPropertyBindingPrivate *>(newBinding.data());
-        newBindingRaw->setDirty(true);
         newBindingRaw->setProperty(propertyDataPtr);
         if (observer)
             newBindingRaw->prependObserver(observer);
         newBindingRaw->setStaticObserver(staticObserverCallback, guardCallback);
-        if (newBindingRaw->requiresEagerEvaluation()) {
-            newBindingRaw->setEagerlyUpdating(true);
-            auto changed = newBindingRaw->evaluateIfDirtyAndReturnTrueIfValueChanged(propertyDataPtr);
-            if (changed)
-                observer.notify(newBindingRaw, propertyDataPtr, /*knownToHaveChanged=*/true);
-            newBindingRaw->setEagerlyUpdating(false);
-        }
+
+        newBindingRaw->evaluate();
     } else if (observer) {
         d.setObservers(observer.ptr);
     } else {
@@ -333,13 +303,9 @@ QPropertyBindingPrivate *QPropertyBindingPrivate::currentlyEvaluatingBinding()
     return currentState ? currentState->binding : nullptr;
 }
 
-void QPropertyBindingData::evaluateIfDirty(const QUntypedPropertyData *property) const
+// ### Unused, kept for BC with 6.0
+void QPropertyBindingData::evaluateIfDirty(const QUntypedPropertyData *) const
 {
-    QPropertyBindingDataPointer d{this};
-    QPropertyBindingPrivate *binding = d.bindingPtr();
-    if (!binding)
-        return;
-    binding->evaluateIfDirtyAndReturnTrueIfValueChanged(property);
 }
 
 void QPropertyBindingData::removeBinding_helper()
@@ -370,7 +336,7 @@ void QPropertyBindingData::registerWithCurrentlyEvaluatingBinding_helper(Binding
     QPropertyBindingDataPointer d{this};
 
     QPropertyObserverPointer dependencyObserver = currentState->binding->allocateDependencyObserver();
-    dependencyObserver.setBindingToMarkDirty(currentState->binding);
+    dependencyObserver.setBindingToNotify(currentState->binding);
     dependencyObserver.observeProperty(d);
 }
 
@@ -378,14 +344,7 @@ void QPropertyBindingData::notifyObservers(QUntypedPropertyData *propertyDataPtr
 {
     QPropertyBindingDataPointer d{this};
     if (QPropertyObserverPointer observer = d.firstObserver())
-        observer.notify(d.bindingPtr(), propertyDataPtr);
-}
-
-void QPropertyBindingData::markDirty()
-{
-    QPropertyBindingDataPointer d{this};
-    if (auto *binding = d.bindingPtr())
-        binding->setDirty(true);
+        observer.notify(propertyDataPtr);
 }
 
 int QPropertyBindingDataPointer::observerCount() const
@@ -425,7 +384,7 @@ QPropertyObserver::~QPropertyObserver()
 
 QPropertyObserver::QPropertyObserver(QPropertyObserver &&other) noexcept
 {
-    bindingToMarkDirty = std::exchange(other.bindingToMarkDirty, {});
+    binding = std::exchange(other.binding, {});
     next = std::exchange(other.next, {});
     prev = std::exchange(other.prev, {});
     if (next)
@@ -441,9 +400,9 @@ QPropertyObserver &QPropertyObserver::operator=(QPropertyObserver &&other) noexc
 
     QPropertyObserverPointer d{this};
     d.unlink();
-    bindingToMarkDirty = nullptr;
+    binding = nullptr;
 
-    bindingToMarkDirty = std::exchange(other.bindingToMarkDirty, {});
+    binding = std::exchange(other.binding, {});
     next = std::exchange(other.next, {});
     prev = std::exchange(other.prev, {});
     if (next)
@@ -480,10 +439,10 @@ void QPropertyObserverPointer::setAliasedProperty(QUntypedPropertyData *property
     ptr->next.setTag(QPropertyObserver::ObserverNotifiesAlias);
 }
 
-void QPropertyObserverPointer::setBindingToMarkDirty(QPropertyBindingPrivate *binding)
+void QPropertyObserverPointer::setBindingToNotify(QPropertyBindingPrivate *binding)
 {
     Q_ASSERT(ptr->next.tag() != QPropertyObserver::ObserverIsPlaceholder);
-    ptr->bindingToMarkDirty = binding;
+    ptr->binding = binding;
     ptr->next.setTag(QPropertyObserver::ObserverNotifiesBinding);
 }
 
@@ -516,14 +475,8 @@ struct [[nodiscard]] QPropertyObserverNodeProtector {
 
 /*! \internal
   \a propertyDataPtr is a pointer to the observed property's property data
-  In case that property has a binding, \a triggeringBinding points to the binding's QPropertyBindingPrivate
-  \a alreadyKnownToHaveChanged is an optional parameter, which is needed in the case
-  of eager evaluation:
-  There, we have already evaluated the binding, and thus the change detection for the
-  ObserverNotifiesChangeHandler case would not work. Thus we instead pass the knowledge of
-  whether the value has changed we obtained when evaluating the binding eagerly along
  */
-void QPropertyObserverPointer::notify(QPropertyBindingPrivate *triggeringBinding, QUntypedPropertyData *propertyDataPtr, bool knownToHaveChanged)
+void QPropertyObserverPointer::notify(QUntypedPropertyData *propertyDataPtr)
 {
     auto observer = const_cast<QPropertyObserver*>(ptr);
     /*
@@ -557,22 +510,17 @@ void QPropertyObserverPointer::notify(QPropertyBindingPrivate *triggeringBinding
                 observer = next->next.data();
                 continue;
             }
-            // both evaluateIfDirtyAndReturnTrueIfValueChanged and handlerToCall might modify the list
+            // handlerToCall might modify the list
             QPropertyObserverNodeProtector protector(observer);
-            if (!knownToHaveChanged && triggeringBinding) {
-                if (!triggeringBinding->evaluateIfDirtyAndReturnTrueIfValueChanged(propertyDataPtr))
-                    return;
-                knownToHaveChanged = true;
-            }
             handlerToCall(observer, propertyDataPtr);
             next = protector.next();
             break;
         }
         case QPropertyObserver::ObserverNotifiesBinding:
         {
-            auto bindingToMarkDirty =  observer->bindingToMarkDirty;
+            auto bindingToMarkDirty =  observer->binding;
             QPropertyObserverNodeProtector protector(observer);
-            bindingToMarkDirty->markDirtyAndNotifyObservers();
+            bindingToMarkDirty->evaluate();
             next = protector.next();
             break;
         }
@@ -1873,18 +1821,23 @@ QBindingStorage::~QBindingStorage()
     QBindingStoragePrivate(d).destroy();
 }
 
+// ### Unused, retained for BC with 6.0
 void QBindingStorage::maybeUpdateBindingAndRegister_helper(const QUntypedPropertyData *data) const
 {
+    registerDependency_helper(data);
+}
+
+void QBindingStorage::registerDependency_helper(const QUntypedPropertyData *data) const
+{
     Q_ASSERT(bindingStatus);
     QUntypedPropertyData *dd = const_cast<QUntypedPropertyData *>(data);
     auto storage = QBindingStoragePrivate(d).get(dd, /*create=*/ bindingStatus->currentlyEvaluatingBinding != nullptr);
     if (!storage)
         return;
-    if (auto *binding = storage->binding())
-        binding->evaluateIfDirtyAndReturnTrueIfValueChanged(const_cast<QUntypedPropertyData *>(data), bindingStatus);
     storage->registerWithCurrentlyEvaluatingBinding(bindingStatus->currentlyEvaluatingBinding);
 }
 
+
 QPropertyBindingData *QBindingStorage::bindingData_helper(const QUntypedPropertyData *data) const
 {
     return QBindingStoragePrivate(d).get(data);
diff --git a/src/corelib/kernel/qproperty.h b/src/corelib/kernel/qproperty.h
index 717c6713d4..40b7a9452d 100644
--- a/src/corelib/kernel/qproperty.h
+++ b/src/corelib/kernel/qproperty.h
@@ -229,7 +229,7 @@ private:
     QtPrivate::QTagPreservingPointerToPointer<QPropertyObserver, ObserverTag> prev;
 
     union {
-        QPropertyBindingPrivate *bindingToMarkDirty = nullptr;
+        QPropertyBindingPrivate *binding = nullptr;
         ChangeHandler changeHandler;
         QUntypedPropertyData *aliasedPropertyData;
     };
@@ -329,8 +329,6 @@ public:
 
     parameter_type value() const
     {
-        if (d.hasBinding())
-            d.evaluateIfDirty(this);
         d.registerWithCurrentlyEvaluatingBinding();
         return this->val;
     }
@@ -389,9 +387,7 @@ public:
 
     QPropertyBinding<T> setBinding(const QPropertyBinding<T> &newBinding)
     {
-        QPropertyBinding<T> oldBinding(d.setBinding(newBinding, this));
-        notify();
-        return oldBinding;
+        return QPropertyBinding<T>(d.setBinding(newBinding, this));
     }
 
     bool setBinding(const QUntypedPropertyBinding &newBinding)
@@ -402,11 +398,6 @@ public:
         return true;
     }
 
-    void markDirty() {
-        d.markDirty();
-        notify();
-    }
-
 #ifndef Q_CLANG_QDOC
     template <typename Functor>
     QPropertyBinding<T> setBinding(Functor &&f,
@@ -852,11 +843,11 @@ public:
 
     bool isEmpty() { return !d; }
 
-    void maybeUpdateBindingAndRegister(const QUntypedPropertyData *data) const
+    void registerDependency(const QUntypedPropertyData *data) const
     {
         if (!d && !bindingStatus->currentlyEvaluatingBinding)
             return;
-        maybeUpdateBindingAndRegister_helper(data);
+        registerDependency_helper(data);
     }
     QtPrivate::QPropertyBindingData *bindingData(const QUntypedPropertyData *data) const
     {
@@ -864,6 +855,9 @@ public:
             return nullptr;
         return bindingData_helper(data);
     }
+    // ### Qt 7: remove unused BIC shim
+    void maybeUpdateBindingAndRegister(const QUntypedPropertyData *data) const { registerDependency(data); }
+
     QtPrivate::QPropertyBindingData *bindingData(QUntypedPropertyData *data, bool create)
     {
         if (!d && !create)
@@ -871,6 +865,8 @@ public:
         return bindingData_helper(data, create);
     }
 private:
+    void registerDependency_helper(const QUntypedPropertyData *data) const;
+    // ### Unused, but keep for BC
     void maybeUpdateBindingAndRegister_helper(const QUntypedPropertyData *data) const;
     QtPrivate::QPropertyBindingData *bindingData_helper(const QUntypedPropertyData *data) const;
     QtPrivate::QPropertyBindingData *bindingData_helper(QUntypedPropertyData *data, bool create);
@@ -923,7 +919,7 @@ public:
 
     parameter_type value() const
     {
-        qGetBindingStorage(owner())->maybeUpdateBindingAndRegister(this);
+        qGetBindingStorage(owner())->registerDependency(this);
         return this->val;
     }
 
@@ -987,7 +983,6 @@ public:
     {
         QtPrivate::QPropertyBindingData *bd = qGetBindingStorage(owner())->bindingData(this, true);
         QUntypedPropertyBinding oldBinding(bd->setBinding(newBinding, this, HasSignal ? &signalCallBack : nullptr));
-        notify(bd);
         return static_cast<QPropertyBinding<T> &>(oldBinding);
     }
 
@@ -1018,15 +1013,6 @@ public:
         return bd && bd->binding() != nullptr;
     }
 
-    void markDirty() {
-        QBindingStorage *storage = qGetBindingStorage(owner());
-        auto bd = storage->bindingData(this, /*create=*/false);
-        if (bd) { // if we have no BindingData, nobody can listen anyway
-            bd->markDirty();
-            notify(bd);
-        }
-    }
-
     QPropertyBinding<T> binding() const
     {
         auto *bd = qGetBindingStorage(owner())->bindingData(this);
@@ -1130,7 +1116,7 @@ public:
 
     parameter_type value() const
     {
-        qGetBindingStorage(owner())->maybeUpdateBindingAndRegister(this);
+        qGetBindingStorage(owner())->registerDependency(this);
         return (owner()->*Getter)();
     }
 
@@ -1176,15 +1162,13 @@ public:
         return *storage->bindingData(const_cast<QObjectComputedProperty *>(this), true);
     }
 
-    void markDirty() {
+    void notify() {
         // computed property can't store a binding, so there's nothing to mark
         auto *storage = const_cast<QBindingStorage *>(qGetBindingStorage(owner()));
         auto bd = storage->bindingData(const_cast<QObjectComputedProperty *>(this), false);
         if (bd)
-            bindingData().notifyObservers(this);
+            bd->notifyObservers(this);
     }
-
-private:
 };
 
 #define Q_OBJECT_COMPUTED_PROPERTY(Class, Type, name,  ...) \
diff --git a/src/corelib/kernel/qproperty_p.h b/src/corelib/kernel/qproperty_p.h
index d459433528..00978e8ea6 100644
--- a/src/corelib/kernel/qproperty_p.h
+++ b/src/corelib/kernel/qproperty_p.h
@@ -104,11 +104,11 @@ struct QPropertyObserverPointer
 
     void unlink();
 
-    void setBindingToMarkDirty(QPropertyBindingPrivate *binding);
+    void setBindingToNotify(QPropertyBindingPrivate *binding);
     void setChangeHandler(QPropertyObserver::ChangeHandler changeHandler);
     void setAliasedProperty(QUntypedPropertyData *propertyPtr);
 
-    void notify(QPropertyBindingPrivate *triggeringBinding, QUntypedPropertyData *propertyDataPtr, bool knownToHaveChanged = false);
+    void notify(QUntypedPropertyData *propertyDataPtr);
     void observeProperty(QPropertyBindingDataPointer property);
 
     explicit operator bool() const { return ptr != nullptr; }
@@ -172,14 +172,11 @@ private:
 
 private:
 
-    // a dependent property has changed, and the binding needs to be reevaluated on access
-    bool dirty = false;
     // used to detect binding loops for lazy evaluated properties
     bool updating = false;
     bool hasStaticObserver = false;
     bool hasBindingWrapper:1;
     // used to detect binding loops for eagerly evaluated properties
-    bool eagerlyUpdating:1;
     bool isQQmlPropertyBinding:1;
 
     const QtPrivate::BindingFunctionVTable *vtable;
@@ -230,13 +227,11 @@ public:
     // public because the auto-tests access it, too.
     size_t dependencyObserverCount = 0;
 
-    bool isEagerlyUpdating() {return eagerlyUpdating;}
-    void setEagerlyUpdating(bool b) {eagerlyUpdating = b;}
+    bool isUpdating() {return updating;}
 
     QPropertyBindingPrivate(QMetaType metaType, const QtPrivate::BindingFunctionVTable *vtable,
                             const QPropertyBindingSourceLocation &location, bool isQQmlPropertyBinding=false)
         : hasBindingWrapper(false)
-        , eagerlyUpdating(false)
         , isQQmlPropertyBinding(isQQmlPropertyBinding)
         , vtable(vtable)
         , location(location)
@@ -245,7 +240,6 @@ public:
     ~QPropertyBindingPrivate();
 
 
-    void setDirty(bool d) { dirty = d; }
     void setProperty(QUntypedPropertyData *propertyPtr) { propertyDataPtr = propertyPtr; }
     void setStaticObserver(QtPrivate::QPropertyObserverCallback callback, QtPrivate::QPropertyBindingWrapper bindingWrapper)
     {
@@ -312,13 +306,7 @@ public:
 
     void unlinkAndDeref();
 
-    void markDirtyAndNotifyObservers();
-    bool evaluateIfDirtyAndReturnTrueIfValueChanged(const QUntypedPropertyData *data, QBindingStatus *status = nullptr)
-    {
-        if (!dirty)
-            return false;
-        return evaluateIfDirtyAndReturnTrueIfValueChanged_helper(data, status);
-    }
+    void evaluate();
 
     static QPropertyBindingPrivate *get(const QUntypedPropertyBinding &binding)
     { return static_cast<QPropertyBindingPrivate *>(binding.d.data()); }
@@ -334,8 +322,6 @@ public:
         clearDependencyObservers();
     }
 
-    bool requiresEagerEvaluation() const { return hasBindingWrapper; }
-
     static QPropertyBindingPrivate *currentlyEvaluatingBinding();
 
     bool hasCustomVTable() const
@@ -353,9 +339,6 @@ public:
             delete[] reinterpret_cast<std::byte *>(priv);
         }
     }
-
-private:
-    bool evaluateIfDirtyAndReturnTrueIfValueChanged_helper(const QUntypedPropertyData *data, QBindingStatus *status = nullptr);
 };
 
 inline void QPropertyBindingDataPointer::setFirstObserver(QPropertyObserver *observer)
@@ -434,7 +417,7 @@ public:
         const QBindingStorage *storage = qGetBindingStorage(owner());
         // make sure we don't register this binding as a dependency to itself
         if (!inBindingWrapper(storage))
-            storage->maybeUpdateBindingAndRegister(this);
+            storage->registerDependency(this);
         return this->val;
     }
 
@@ -511,15 +494,6 @@ public:
         return bd && bd->binding() != nullptr;
     }
 
-    void markDirty() {
-        QBindingStorage *storage = qGetBindingStorage(owner());
-        auto *bd = storage->bindingData(this, false);
-        if (bd) {
-            bd->markDirty();
-            notify(bd);
-        }
-    }
-
     void removeBindingUnlessInWrapper()
     {
         QBindingStorage *storage = qGetBindingStorage(owner());
@@ -576,6 +550,7 @@ public:
         auto *storage = const_cast<QBindingStorage *>(qGetBindingStorage(owner()));
         return *storage->bindingData(const_cast<QObjectCompatProperty *>(this), true);
     }
+
 private:
     void notify(const QtPrivate::QPropertyBindingData *binding)
     {
diff --git a/src/corelib/kernel/qpropertyprivate.h b/src/corelib/kernel/qpropertyprivate.h
index 896ad17395..b6d93529d1 100644
--- a/src/corelib/kernel/qpropertyprivate.h
+++ b/src/corelib/kernel/qpropertyprivate.h
@@ -249,8 +249,7 @@ public:
 
     }
 
-    void evaluateIfDirty(const QUntypedPropertyData *property) const;
-    void markDirty();
+    void evaluateIfDirty(const QUntypedPropertyData *) const; // ### Kept for BC reasons, unused
 
     void removeBinding()
     {
diff --git a/src/corelib/kernel/qtimer.cpp b/src/corelib/kernel/qtimer.cpp
index 333e6c24ba..10e26fcdef 100644
--- a/src/corelib/kernel/qtimer.cpp
+++ b/src/corelib/kernel/qtimer.cpp
@@ -241,7 +241,7 @@ void QTimer::start()
         stop();
     d->nulltimer = (!d->inter && d->single);
     d->id = QObject::startTimer(d->inter, d->type);
-    d->isActiveData.markDirty();
+    d->isActiveData.notify();
 }
 
 /*!
@@ -278,7 +278,7 @@ void QTimer::stop()
     if (d->id != INV_TIMER) {
         QObject::killTimer(d->id);
         d->id = INV_TIMER;
-        d->isActiveData.markDirty();
+        d->isActiveData.notify();
     }
 }
 
@@ -763,9 +763,8 @@ void QTimer::setInterval(int msec)
         // No need to call markDirty() for d->isActiveData here,
         // as timer state actually does not change
     }
-
     if (intervalChanged)
-        d->inter.markDirty();
+        d->inter.notify();
 }
 
 int QTimer::interval() const