QSGDepthStencilBufferManager: don't use toStrongRef().data()

It's an anti-pattern.

Even though we don't expect other threads to destroy the last QSP
while we use the pointer obtained from QWeakPointer, play it safe
and use QWeakPointer idiomatically: as a non-owning reference, to
be converted to an owning one for the duration of our use of the
payload object.

Add an assertion that explains why we don't expect expired weak_ptrs
here.

Amends 0f035c0ad79ca41a1473b64a4c0077e7085d3700.

Change-Id: Ia39ef5fa243e0e73110aae13da35f4f2ada73a73
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 3 insertions, 1 deletions

diff --git a/src/quick/scenegraph/util/qsgdepthstencilbuffer.cpp b/src/quick/scenegraph/util/qsgdepthstencilbuffer.cpp
index a850f72053..1154c06d7c 100644
--- a/src/quick/scenegraph/util/qsgdepthstencilbuffer.cpp
+++ b/src/quick/scenegraph/util/qsgdepthstencilbuffer.cpp
@@ -183,7 +183,9 @@ void QSGDefaultDepthStencilBuffer::free()
 QSGDepthStencilBufferManager::~QSGDepthStencilBufferManager()
 {
     for (Hash::const_iterator it = m_buffers.constBegin(), cend = m_buffers.constEnd(); it != cend; ++it) {
-        QSGDepthStencilBuffer *buffer = it.value().toStrongRef().data();
+        QSharedPointer<QSGDepthStencilBuffer> buffer = it.value().toStrongRef();
+        Q_ASSERT_X(buffer, "~QSGDepthStencilBufferManager",
+                   "~QSGDepthStencilBuffer is supposed to unregister from the manager");
         buffer->free();
         buffer->m_manager = nullptr;
     }