QML: Don't crash when calling coerceAndCall() with null thisObject

Pick-to: 6.6 6.5
Fixes: QTBUG-119395
Change-Id: I5877beef9a53d358a6f58f9ce5029688bd9dcedb
Reviewed-by: Olivier De Cannière <olivier.decanniere@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

3 files changed, 32 insertions, 0 deletions

diff --git a/tests/auto/qml/qmlcppcodegen/data/CMakeLists.txt b/tests/auto/qml/qmlcppcodegen/data/CMakeLists.txt
index 9d5124c87a..dc4216ba6d 100644
--- a/tests/auto/qml/qmlcppcodegen/data/CMakeLists.txt
+++ b/tests/auto/qml/qmlcppcodegen/data/CMakeLists.txt
@@ -210,6 +210,7 @@ set(qml_files
     popContextAfterRet.qml
     prefixedMetaType.qml
     pressAndHoldButton.qml
+    reduceWithNullThis.qml
     readEnumFromInstance.qml
     registerPropagation.qml
     registerelimination.qml
diff --git a/tests/auto/qml/qmlcppcodegen/data/reduceWithNullThis.qml b/tests/auto/qml/qmlcppcodegen/data/reduceWithNullThis.qml
new file mode 100644
index 0000000000..c6fda8c739
--- /dev/null
+++ b/tests/auto/qml/qmlcppcodegen/data/reduceWithNullThis.qml
@@ -0,0 +1,18 @@
+import QtQml
+
+QtObject {
+    id: mainItem
+    property int topPadding: 12
+    property int bottomPadding: 12
+
+    property int preferredHeight: mainItem.children.reduce(maximumImplicitHeightReducer, 0) + topPadding + bottomPadding
+    function maximumImplicitHeightReducer(accumulator: real, item: Binding): real {
+        return Math.max(accumulator, (item.objectName + "b").length);
+    }
+
+    property int preferredHeight2: mainItem.children.reduce((accumulator, item) => {
+        return Math.max(accumulator, (item.objectName + "b").length);
+    }, 0) + topPadding + bottomPadding
+
+    property list<Binding> children: [ Binding { objectName: "aaa" } ]
+}
diff --git a/tests/auto/qml/qmlcppcodegen/tst_qmlcppcodegen.cpp b/tests/auto/qml/qmlcppcodegen/tst_qmlcppcodegen.cpp
index 259bac97e8..30a3eca882 100644
--- a/tests/auto/qml/qmlcppcodegen/tst_qmlcppcodegen.cpp
+++ b/tests/auto/qml/qmlcppcodegen/tst_qmlcppcodegen.cpp
@@ -178,6 +178,7 @@ private slots:
     void popContextAfterRet();
     void prefixedType();
     void propertyOfParent();
+    void reduceWithNullThis();
     void readEnumFromInstance();
     void registerElimination();
     void registerPropagation();
@@ -3711,6 +3712,18 @@ void tst_QmlCppCodegen::propertyOfParent()
     }
 }
 
+void tst_QmlCppCodegen::reduceWithNullThis()
+{
+    QQmlEngine engine;
+    QQmlComponent component(&engine, QUrl(u"qrc:/qt/qml/TestTypes/reduceWithNullThis.qml"_s));
+    QVERIFY2(component.isReady(), component.errorString().toUtf8());
+    QScopedPointer<QObject> object(component.create());
+    QVERIFY(!object.isNull());
+
+    QCOMPARE(object->property("preferredHeight").toDouble(), 28.0);
+    QCOMPARE(object->property("preferredHeight2").toDouble(), 28.0);
+}
+
 void tst_QmlCppCodegen::readEnumFromInstance()
 {
     QQmlEngine engine;