4 files changed, 45 insertions, 8 deletions

diff --git a/src/qml/jsruntime/qv4referenceobject_p.h b/src/qml/jsruntime/qv4referenceobject_p.h
index 3dfea409db..61b8f02206 100644
--- a/src/qml/jsruntime/qv4referenceobject_p.h
+++ b/src/qml/jsruntime/qv4referenceobject_p.h
@@ -32,6 +32,7 @@ DECLARE_HEAP_OBJECT(ReferenceObject, Object) {
         NoFlag           = 0,
         CanWriteBack     = 1 << 0,
         IsVariant        = 1 << 1,
+        EnforcesLocation = 1 << 2,
     };
     Q_DECLARE_FLAGS(Flags, Flag);
 
@@ -59,6 +60,33 @@ DECLARE_HEAP_OBJECT(ReferenceObject, Object) {
     void setIsVariant(bool isVariant) { setFlag(IsVariant, isVariant); }
     bool isVariant() const { return hasFlag(IsVariant); }
 
+
+    void setEnforcesLocation(bool enforces) { setFlag(EnforcesLocation, enforces); }
+    bool enforcesLocation() const { return hasFlag(EnforcesLocation); }
+
+    void setLocation(const Function *function, quint16 statement)
+    {
+        m_function = function;
+        m_statementIndex = statement;
+    }
+
+    const Function *function() const { return m_function; }
+    quint16 statementIndex() const { return m_statementIndex; }
+
+    bool isAttachedToProperty() const
+    {
+        if (enforcesLocation()) {
+            if (CppStackFrame *frame = internalClass->engine->currentStackFrame) {
+                if (frame->v4Function != function() || frame->statementNumber() != statementIndex())
+                    return false;
+            } else {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     bool isReference() const { return m_property >= 0; }
 
 private:
@@ -74,7 +102,9 @@ private:
     }
 
     QV4QPointer<QObject> m_object;
+    const Function *m_function;
     int m_property;
+    quint16 m_statementIndex;
     quint8 m_flags;
 };
 
diff --git a/src/qml/jsruntime/qv4sequenceobject.cpp b/src/qml/jsruntime/qv4sequenceobject.cpp
index 2558e376b5..6aadf68c05 100644
--- a/src/qml/jsruntime/qv4sequenceobject.cpp
+++ b/src/qml/jsruntime/qv4sequenceobject.cpp
@@ -162,6 +162,8 @@ void Heap::Sequence::init(
     QV4::Scope scope(internalClass->engine);
     QV4::Scoped<QV4::Sequence> o(scope, this);
     o->setArrayType(Heap::ArrayData::Custom);
+    if (CppStackFrame *frame = scope.engine->currentStackFrame)
+        setLocation(frame->v4Function, frame->statementNumber());
     o->loadReference();
 }
 
@@ -422,18 +424,19 @@ bool Sequence::sort(const FunctionObject *f, const Value *, const Value *argv, i
 void *Sequence::getRawContainerPtr() const
 { return d()->storagePointer(); }
 
-void Sequence::loadReference() const
+bool Sequence::loadReference() const
 {
     Q_ASSERT(d()->object());
     Q_ASSERT(d()->isReference());
-    QV4::ReferenceObject::readReference(d());
+    // If locations are enforced we only read once
+    return d()->enforcesLocation() || QV4::ReferenceObject::readReference(d());
 }
 
-void Sequence::storeReference()
+bool Sequence::storeReference()
 {
     Q_ASSERT(d()->object());
     Q_ASSERT(d()->isReference());
-    QV4::ReferenceObject::writeBack(d());
+    return d()->isAttachedToProperty() && QV4::ReferenceObject::writeBack(d());
 }
 
 ReturnedValue Sequence::virtualGet(const Managed *that, PropertyKey id, const Value *receiver, bool *hasProperty)
diff --git a/src/qml/jsruntime/qv4sequenceobject_p.h b/src/qml/jsruntime/qv4sequenceobject_p.h
index 6d0a85ded6..f6055e38e3 100644
--- a/src/qml/jsruntime/qv4sequenceobject_p.h
+++ b/src/qml/jsruntime/qv4sequenceobject_p.h
@@ -100,8 +100,8 @@ public:
     bool containerIsEqualTo(Managed *other);
     bool sort(const FunctionObject *f, const Value *, const Value *argv, int argc);
     void *getRawContainerPtr() const;
-    void loadReference() const;
-    void storeReference();
+    bool loadReference() const;
+    bool storeReference();
 };
 
 }
diff --git a/src/qml/qml/qqmlvaluetypewrapper.cpp b/src/qml/qml/qqmlvaluetypewrapper.cpp
index 2e7eaf23f8..721917bb6d 100644
--- a/src/qml/qml/qqmlvaluetypewrapper.cpp
+++ b/src/qml/qml/qqmlvaluetypewrapper.cpp
@@ -109,12 +109,13 @@ void *Heap::QQmlValueTypeWrapper::storagePointer()
 
 bool Heap::QQmlValueTypeWrapper::readReference()
 {
-    return QV4::ReferenceObject::readReference(this);
+    // If locations are enforced we only read once
+    return enforcesLocation() || QV4::ReferenceObject::readReference(this);
 }
 
 bool Heap::QQmlValueTypeWrapper::writeBack()
 {
-    return QV4::ReferenceObject::writeBack(this);
+    return isAttachedToProperty() && QV4::ReferenceObject::writeBack(this);
 }
 
 ReturnedValue QQmlValueTypeWrapper::create(
@@ -130,6 +131,7 @@ ReturnedValue QQmlValueTypeWrapper::create(
     r->d()->setMetaObject(cloneFrom->metaObject());
     r->d()->setValueType(cloneFrom->valueType());
     r->d()->setGadgetPtr(nullptr);
+    r->d()->setLocation(cloneFrom->function(), cloneFrom->statementIndex());
     return r->asReturnedValue();
 }
 
@@ -160,6 +162,8 @@ ReturnedValue QQmlValueTypeWrapper::create(ExecutionEngine *engine, QObject *obj
     }
     r->d()->setValueType(valueType);
     r->d()->setGadgetPtr(nullptr);
+    if (CppStackFrame *frame = engine->currentStackFrame)
+        r->d()->setLocation(frame->v4Function, frame->statementNumber());
     return r->asReturnedValue();
 }