From 83100a84f2b0068b4cf725896bbb810415908334 Mon Sep 17 00:00:00 2001
From: Maximilian Goldstein <max.goldstein@qt.io>
Date: Tue, 8 Dec 2020 09:26:36 +0100
Subject: [PATCH 18/28] qqmlistmodel: Fix crash when modelCache is null

Fixes: QTBUG-89173
Change-Id: Ife82518808fc5504ec42407e80ed3de89ed4adeb
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit c3860cd04bbc089ef95bc441a1f8f1e46f9606f8)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/qmlmodels/qqmllistmodel.cpp               |  2 +-
 .../qml/qqmllistmodel/tst_qqmllistmodel.cpp   | 22 +++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/qmlmodels/qqmllistmodel.cpp b/src/qmlmodels/qqmllistmodel.cpp
index e07951cab3..8830e08097 100644
--- a/src/qmlmodels/qqmllistmodel.cpp
+++ b/src/qmlmodels/qqmllistmodel.cpp
@@ -703,7 +703,7 @@ void ListModel::set(int elementIndex, QV4::Object *object, ListModel::SetElement
         } else if (propertyValue->isNullOrUndefined()) {
             if (reason == SetElement::WasJustInserted) {
                 QQmlError err;
-                auto memberName = propertyName->toString(m_modelCache->engine())->toQString();
+                auto memberName = propertyName->toString(v4)->toQString();
                 err.setDescription(QString::fromLatin1("%1 is %2. Adding an object with a %2 member does not create a role for it.").arg(memberName, propertyValue->isNull() ? QLatin1String("null") : QLatin1String("undefined")));
                 qmlWarning(nullptr, err);
             } else {
diff --git a/tests/auto/qml/qqmllistmodel/tst_qqmllistmodel.cpp b/tests/auto/qml/qqmllistmodel/tst_qqmllistmodel.cpp
index d54e3467b7..1953798a15 100644
--- a/tests/auto/qml/qqmllistmodel/tst_qqmllistmodel.cpp
+++ b/tests/auto/qml/qqmllistmodel/tst_qqmllistmodel.cpp
@@ -130,6 +130,7 @@ private slots:
     void dynamic_roles_crash_QTBUG_38907();
     void nestedListModelIteration();
     void undefinedAppendShouldCauseError();
+    void nullPropertyCrash();
 };
 
 bool tst_qqmllistmodel::compareVariantList(const QVariantList &testList, QVariant object)
@@ -1723,6 +1724,27 @@ void tst_qqmllistmodel::undefinedAppendShouldCauseError()
     QScopedPointer<QObject>(component.create());
 }
 
+// QTBUG-89173
+void tst_qqmllistmodel::nullPropertyCrash()
+{
+    QQmlEngine engine;
+    QQmlComponent component(&engine);
+    component.setData(
+            R"(import QtQuick 2.15
+            ListView {
+                model: ListModel { id: listModel }
+
+                delegate: Item {}
+
+                Component.onCompleted: {
+                    listModel.append({"a": "value1", "b":[{"c":"value2"}]})
+                    listModel.append({"a": "value2", "b":[{"c":null}]})
+                }
+            })",
+            QUrl());
+    QTest::ignoreMessage(QtMsgType::QtWarningMsg, "<Unknown File>: c is null. Adding an object with a null member does not create a role for it.");
+    QScopedPointer<QObject>(component.create());
+}
 
 QTEST_MAIN(tst_qqmllistmodel)
 
-- 
2.31.1