Windows: fix DeferredDelete events processing on QThread::terminate()

On finishing/terminating a thread, when processing posted events,
we need to consider QThread's own data instead of caller thread's data.
Otherwise we can get into unexpected situations such as double
destruction of an object, premature destruction, etc.

Fixes: QTBUG-103922
Pick-to: 6.4 6.3 6.3.1 6.2 5.15
Change-Id: Idf77221ebbaa0b150ee2d0c296b51829ae8dc30e
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 78 insertions, 0 deletions

diff --git a/tests/auto/corelib/thread/qthread/tst_qthread.cpp b/tests/auto/corelib/thread/qthread/tst_qthread.cpp
index 125c969ea2..b5f2ebdabf 100644
--- a/tests/auto/corelib/thread/qthread/tst_qthread.cpp
+++ b/tests/auto/corelib/thread/qthread/tst_qthread.cpp
@@ -91,6 +91,9 @@ private slots:
     void create();
     void createDestruction();
     void threadIdReuse();
+
+    void terminateAndPrematureDestruction();
+    void terminateAndDoubleDestruction();
 };
 
 enum { one_minute = 60 * 1000, five_minutes = 5 * one_minute };
@@ -1719,5 +1722,80 @@ void tst_QThread::threadIdReuse()
     }
 }
 
+class WaitToRun_Thread : public QThread
+{
+    Q_OBJECT
+public:
+    void run() override
+    {
+        emit running();
+        QThread::exec();
+    }
+
+Q_SIGNALS:
+    void running();
+};
+
+
+void tst_QThread::terminateAndPrematureDestruction()
+{
+    WaitToRun_Thread thread;
+    QSignalSpy spy(&thread, &WaitToRun_Thread::running);
+    thread.start();
+    QVERIFY(spy.wait(500));
+
+    QScopedPointer<QObject> obj(new QObject);
+    QPointer<QObject> pObj(obj.data());
+    obj->deleteLater();
+
+    thread.terminate();
+    QVERIFY2(pObj, "object was deleted prematurely!");
+    thread.wait(500);
+}
+
+void tst_QThread::terminateAndDoubleDestruction()
+{
+    class ChildObject : public QObject
+    {
+    public:
+        ChildObject(QObject *parent)
+            : QObject(parent)
+        {
+            QSignalSpy spy(&thread, &WaitToRun_Thread::running);
+            thread.start();
+            spy.wait(500);
+        }
+
+        ~ChildObject()
+        {
+            QVERIFY2(!inDestruction, "Double object destruction!");
+            inDestruction = true;
+            thread.terminate();
+            thread.wait(500);
+        }
+
+        bool inDestruction = false;
+        WaitToRun_Thread thread;
+    };
+
+    class TestObject : public QObject
+    {
+    public:
+        TestObject()
+            : child(new ChildObject(this))
+        {
+        }
+
+        ~TestObject()
+        {
+            child->deleteLater();
+        }
+
+        ChildObject *child = nullptr;
+    };
+
+    TestObject obj;
+}
+
 QTEST_MAIN(tst_QThread)
 #include "tst_qthread.moc"