From ef7cda00dd64acca3a5fa48ee3cb129c781506f2 Mon Sep 17 00:00:00 2001
From: Allan Sandfeld Jensen <allan.jensen@qt.io>
Date: Fri, 17 Jun 2022 12:36:21 +0200
Subject: [PATCH] Avoid misleading bindingStatus

Set it to nullptr on clear, and deal with possibly null bindingStatus.

Task-number: QTBUG-101177
Task-number: QTBUG-102403
Change-Id: I66cb4d505a4f7b377dc90b45ac13834fca19d399
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
(cherry picked from commit 0bd287627508c61a7abfd6430d8c1243ea153081)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/corelib/kernel/qbindingstorage.h          |  2 +-
 src/corelib/kernel/qobject.cpp                |  2 +-
 src/corelib/kernel/qproperty.cpp              |  1 +
 src/corelib/kernel/qproperty_p.h              |  4 +-
 .../kernel/qproperty/tst_qproperty.cpp        | 38 ++++++++++++++++++-
 5 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/src/corelib/kernel/qbindingstorage.h b/src/corelib/kernel/qbindingstorage.h
index d8853fa265f..8baf1b40e15 100644
--- a/src/corelib/kernel/qbindingstorage.h
+++ b/src/corelib/kernel/qbindingstorage.h
@@ -55,7 +55,7 @@ public:
 
     void registerDependency(const QUntypedPropertyData *data) const
     {
-        if (!bindingStatus->currentlyEvaluatingBinding)
+        if (!bindingStatus || !bindingStatus->currentlyEvaluatingBinding)
             return;
         registerDependency_helper(data);
     }
diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index 05a881b63c2..ebdc9e43f0f 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -1873,9 +1873,9 @@ void QObjectPrivate::moveToThread_helper()
     Q_Q(QObject);
     QEvent e(QEvent::ThreadChange);
     QCoreApplication::sendEvent(q, &e);
+    bindingStorage.clear();
     for (int i = 0; i < children.size(); ++i) {
         QObject *child = children.at(i);
-        child->d_func()->bindingStorage.clear();
         child->d_func()->moveToThread_helper();
     }
 }
diff --git a/src/corelib/kernel/qproperty.cpp b/src/corelib/kernel/qproperty.cpp
index 55e30c3069a..482ed3bf350 100644
--- a/src/corelib/kernel/qproperty.cpp
+++ b/src/corelib/kernel/qproperty.cpp
@@ -2193,6 +2193,7 @@ void QBindingStorage::clear()
 {
     QBindingStoragePrivate(d).destroy();
     d = nullptr;
+    bindingStatus = nullptr;
 }
 
 void QBindingStorage::registerDependency_helper(const QUntypedPropertyData *data) const
diff --git a/src/corelib/kernel/qproperty_p.h b/src/corelib/kernel/qproperty_p.h
index 00e811f4c3f..a569c172c51 100644
--- a/src/corelib/kernel/qproperty_p.h
+++ b/src/corelib/kernel/qproperty_p.h
@@ -442,7 +442,7 @@ class QObjectCompatProperty : public QPropertyData<T>
     }
     bool inBindingWrapper(const QBindingStorage *storage) const
     {
-        return storage->bindingStatus->currentCompatProperty
+        return storage->bindingStatus && storage->bindingStatus->currentCompatProperty
             && QtPrivate::isPropertyInBindingWrapper(this);
     }
 
@@ -467,7 +467,7 @@ public:
     {
         const QBindingStorage *storage = qGetBindingStorage(owner());
         // make sure we don't register this binding as a dependency to itself
-        if (storage->bindingStatus->currentlyEvaluatingBinding && !inBindingWrapper(storage))
+        if (storage->bindingStatus && storage->bindingStatus->currentlyEvaluatingBinding && !inBindingWrapper(storage))
             storage->registerDependency_helper(this);
         return this->val;
     }
diff --git a/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp b/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp
index 92de7725e4d..c0471890ee8 100644
--- a/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp
+++ b/tests/auto/corelib/kernel/qproperty/tst_qproperty.cpp
@@ -79,6 +79,7 @@ private slots:
 
     void noFakeDependencies();
     void threadSafety();
+    void threadSafety2();
 
     void bindablePropertyWithInitialization();
     void noDoubleNotification();
@@ -1694,7 +1695,7 @@ void tst_QProperty::threadSafety()
     auto child1 = new ThreadSafetyTester(obj1);
     obj1->moveToThread(&workerThread);
     const auto mainThreadBindingStatus = QtPrivate::getBindingStatus({});
-    QCOMPARE(qGetBindingStorage(child1)->status({}), mainThreadBindingStatus);
+    QCOMPARE(qGetBindingStorage(child1)->status({}), nullptr);
     workerThread.start();
 
     bool correctStatus = false;
@@ -1743,6 +1744,41 @@ void tst_QProperty::threadSafety()
     QCOMPARE(obj3->objectName(), "moved again");
 }
 
+class QPropertyUsingThread : public QThread
+{
+public:
+    QPropertyUsingThread(QObject **dest, QThread *destThread) : dest(dest), destThread(destThread) {}
+    void run() override
+    {
+        scopedObj1.reset(new ThreadSafetyTester());
+        scopedObj1->setObjectName("test");
+        QObject *child = new ThreadSafetyTester(scopedObj1.get());
+        child->setObjectName("child");
+        exec();
+        scopedObj1->moveToThread(destThread);
+        *dest = scopedObj1.release();
+    }
+    std::unique_ptr<ThreadSafetyTester> scopedObj1;
+    QObject **dest;
+    QThread *destThread;
+};
+
+void tst_QProperty::threadSafety2()
+{
+    std::unique_ptr<QObject> movedObj;
+    {
+        QObject *tmp = nullptr;
+        QPropertyUsingThread workerThread(&tmp, QThread::currentThread());
+        workerThread.start();
+        workerThread.quit();
+        workerThread.wait();
+        movedObj.reset(tmp);
+    }
+
+    QCOMPARE(movedObj->objectName(), "test");
+    QCOMPARE(movedObj->children().first()->objectName(), "child");
+}
+
 struct CustomType
 {
     CustomType() = default;