QQmlDelegateModel: Fix QQmlDelegateModelItem::dataForObject

With required properties, we do not store the cache item as a context
object anymore. To fix this, we repurpose the (space of the) incubator
pointer of QQmlContextData to store the element there, and one of the
dummy bits as a flag to indicate the new usage.

Change-Id: I7cc435fc6781c603fe407411a60a6018239c972c
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

3 files changed, 12 insertions, 6 deletions

diff --git a/src/qml/qml/qqmlcontext.cpp b/src/qml/qml/qqmlcontext.cpp
index 14892bd6ad..668f00b136 100644
--- a/src/qml/qml/qqmlcontext.cpp
+++ b/src/qml/qml/qqmlcontext.cpp
@@ -550,7 +550,7 @@ QQmlContextData::QQmlContextData()
 QQmlContextData::QQmlContextData(QQmlContext *ctxt)
     : engine(nullptr), isInternal(false), isJSContext(false),
       isPragmaLibraryContext(false), unresolvedNames(false), hasEmittedDestruction(false), isRootObjectInCreation(false),
-      stronglyReferencedByParent(false), publicContext(ctxt), incubator(nullptr), componentObjectIndex(-1),
+      stronglyReferencedByParent(false), hasExtraObject(false), publicContext(ctxt), incubator(nullptr), componentObjectIndex(-1),
       contextObject(nullptr), nextChild(nullptr), prevChild(nullptr),
       expressions(nullptr), contextObjects(nullptr), idValues(nullptr), idValueCount(0),
       componentAttached(nullptr)
diff --git a/src/qml/qml/qqmlcontext_p.h b/src/qml/qml/qqmlcontext_p.h
index 5f7316b00c..f93393a11b 100644
--- a/src/qml/qml/qqmlcontext_p.h
+++ b/src/qml/qml/qqmlcontext_p.h
@@ -147,11 +147,16 @@ public:
     quint32 hasEmittedDestruction:1;
     quint32 isRootObjectInCreation:1;
     quint32 stronglyReferencedByParent:1;
-    quint32 dummy:25;
+    quint32 hasExtraObject:1; // used in QQmlDelegateModelItem::dataForObject to find the corresponding QQmlDelegateModelItem of an object
+    quint32 dummy:24;
     QQmlContext *publicContext;
 
-    // The incubator that is constructing this context if any
-    QQmlIncubatorPrivate *incubator;
+    union {
+        // The incubator that is constructing this context if any
+        QQmlIncubatorPrivate *incubator;
+        // a pointer to extra data, currently only used in QQmlDelegateModel
+        QObject *extraObject;
+    };
 
     // Compilation unit for contexts that belong to a compiled type.
     QQmlRefPointer<QV4::ExecutableCompilationUnit> typeCompilationUnit;
diff --git a/src/qml/qml/qqmlincubator.cpp b/src/qml/qml/qqmlincubator.cpp
index 5c3ecbfb60..f0ef5360b0 100644
--- a/src/qml/qml/qqmlincubator.cpp
+++ b/src/qml/qml/qqmlincubator.cpp
@@ -61,7 +61,7 @@ void QQmlEnginePrivate::incubate(QQmlIncubator &i, QQmlContextData *forContext)
         QExplicitlySharedDataPointer<QQmlIncubatorPrivate> parentIncubator;
         QQmlContextData *cctxt = forContext;
         while (cctxt) {
-            if (cctxt->incubator) {
+            if (!cctxt->hasExtraObject && cctxt->incubator) {
                 parentIncubator = cctxt->incubator;
                 break;
             }
@@ -149,7 +149,8 @@ void QQmlIncubatorPrivate::clear()
     }
     enginePriv = nullptr;
     if (!rootContext.isNull()) {
-        rootContext->incubator = nullptr;
+        if (!rootContext->hasExtraObject)
+            rootContext->incubator = nullptr;
         rootContext = nullptr;
     }