QML: Track statement locations in sequence and value types

With this in place we can enforce that reference objects we add in the
future can only be written back in the same statement as they were
created.

Task-number: QTBUG-99766
Change-Id: I1c74bd239caa1bb5febd1a3705d8ee29a8fc4249
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

1 files changed, 7 insertions, 4 deletions

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)