QmlCompiler: Don't access unavailable input accumulator on 'as'

We only read it if the target type is composite. Therefore, check for
composite first, before looking for the accumulator.

Pick-to: 6.6 6.5 6.2
Fixes: QTBUG-119122
Change-Id: I2a50214f76ee4ffe2f877dc690704e7475b8bd77
Reviewed-by: Olivier De Cannière <olivier.decanniere@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

3 files changed, 22 insertions, 3 deletions

diff --git a/src/qmlcompiler/qqmljscodegenerator.cpp b/src/qmlcompiler/qqmljscodegenerator.cpp
index f3c57276e1..3d87a709d7 100644
--- a/src/qmlcompiler/qqmljscodegenerator.cpp
+++ b/src/qmlcompiler/qqmljscodegenerator.cpp
@@ -2861,9 +2861,8 @@ void QQmlJSCodeGenerator::generate_As(int lhs)
                 ? input
                 : convertStored(inputContent.storedType(), genericContained, input);
 
-        if (m_typeResolver->equals(
-                    m_state.accumulatorIn().storedType(), m_typeResolver->metaObjectType())
-                && contained->isComposite()) {
+        if (contained->isComposite() && m_typeResolver->equals(
+                    m_state.accumulatorIn().storedType(), m_typeResolver->metaObjectType())) {
             m_body += conversion(
                         genericContained, outputContent,
                         m_state.accumulatorVariableIn + u"->cast("_s + inputConversion + u')');
diff --git a/tests/auto/qml/qmlcppcodegen/data/asCast.qml b/tests/auto/qml/qmlcppcodegen/data/asCast.qml
index 1befc08d0a..cb8155ca6c 100644
--- a/tests/auto/qml/qmlcppcodegen/data/asCast.qml
+++ b/tests/auto/qml/qmlcppcodegen/data/asCast.qml
@@ -28,4 +28,14 @@ Item {
     property QtObject dummyAsItem: dummy as Item
     property QtObject dummyAsRectangle: dummy as Rectangle
     property QtObject dummyAsDummy: dummy as Dummy
+
+    property QtObject nullAsObject: null as QtObject
+    property QtObject nullAsItem: null as Item
+    property QtObject nullAsRectangle: null as Rectangle
+    property QtObject nullAsDummy: null as Dummy
+
+    property QtObject undefinedAsObject: undefined as QtObject
+    property QtObject undefinedAsItem: undefined as Item
+    property QtObject undefinedAsRectangle: undefined as Rectangle
+    property QtObject undefinedAsDummy: undefined as Dummy
 }
diff --git a/tests/auto/qml/qmlcppcodegen/tst_qmlcppcodegen.cpp b/tests/auto/qml/qmlcppcodegen/tst_qmlcppcodegen.cpp
index 37f874ba91..5d44b84475 100644
--- a/tests/auto/qml/qmlcppcodegen/tst_qmlcppcodegen.cpp
+++ b/tests/auto/qml/qmlcppcodegen/tst_qmlcppcodegen.cpp
@@ -657,6 +657,16 @@ void tst_QmlCppCodegen::asCast()
     QCOMPARE(qvariant_cast<QObject *>(root->property("dummyAsItem")), dummy);
     QCOMPARE(qvariant_cast<QObject *>(root->property("dummyAsRectangle")), nullptr);
     QCOMPARE(qvariant_cast<QObject *>(root->property("dummyAsDummy")), dummy);
+
+    QCOMPARE(qvariant_cast<QObject *>(root->property("nullAsObject")), nullptr);
+    QCOMPARE(qvariant_cast<QObject *>(root->property("nullAsItem")), nullptr);
+    QCOMPARE(qvariant_cast<QObject *>(root->property("nullAsRectangle")), nullptr);
+    QCOMPARE(qvariant_cast<QObject *>(root->property("nullAsDummy")), nullptr);
+
+    QCOMPARE(qvariant_cast<QObject *>(root->property("undefinedAsObject")), nullptr);
+    QCOMPARE(qvariant_cast<QObject *>(root->property("undefinedAsItem")), nullptr);
+    QCOMPARE(qvariant_cast<QObject *>(root->property("undefinedAsRectangle")), nullptr);
+    QCOMPARE(qvariant_cast<QObject *>(root->property("undefinedAsDummy")), nullptr);
 }
 
 void tst_QmlCppCodegen::attachedBaseEnum()