Don't crash on QQmlGadgetPtrWrapper instances in debug service

They have the confusing property of being a QObject but having a
QMetaObject that says it's a Q_GADGET.

Fixes: QTBUG-108646
Change-Id: I6df34c2004918cd89691f4b5eb4b6267dabcd7ff
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit deda185ba95ffb99b1500364e2eba774e9dbc1e6)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 37 insertions, 2 deletions

diff --git a/src/plugins/qmltooling/qmldbg_debugger/qqmlenginedebugservice.cpp b/src/plugins/qmltooling/qmldbg_debugger/qqmlenginedebugservice.cpp
index 1fcc1e7772..578b07cb22 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qqmlenginedebugservice.cpp
+++ b/src/plugins/qmltooling/qmldbg_debugger/qqmlenginedebugservice.cpp
@@ -147,7 +147,8 @@ QQmlEngineDebugServiceImpl::propertyData(QObject *obj, int propIdx)
 {
     QQmlObjectProperty rv;
 
-    QMetaProperty prop = obj->metaObject()->property(propIdx);
+    const QMetaObject *metaObject = obj->metaObject();
+    QMetaProperty prop = metaObject->property(propIdx);
 
     rv.type = QQmlObjectProperty::Unknown;
     rv.valueTypeName = QString::fromUtf8(prop.typeName());
@@ -158,7 +159,10 @@ QQmlEngineDebugServiceImpl::propertyData(QObject *obj, int propIdx)
     if (binding)
         rv.binding = binding->expression();
 
-    rv.value = valueContents(prop.read(obj));
+    if (metaObject->metaType().flags().testFlag(QMetaType::IsGadget))
+        rv.value = valueContents(static_cast<QQmlGadgetPtrWrapper *>(obj)->readOnGadget(prop));
+    else
+        rv.value = valueContents(prop.read(obj));
 
     if (prop.metaType().flags().testFlag(QMetaType::PointerToQObject))  {
         rv.type = QQmlObjectProperty::Object;
diff --git a/tests/auto/qml/debugger/qqmlenginedebugservice/data/fetchValueType.qml b/tests/auto/qml/debugger/qqmlenginedebugservice/data/fetchValueType.qml
new file mode 100644
index 0000000000..ea0c3ff8c0
--- /dev/null
+++ b/tests/auto/qml/debugger/qqmlenginedebugservice/data/fetchValueType.qml
@@ -0,0 +1,9 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+import QtQuick
+import QtQuick.Controls
+
+Item {
+    Button {}
+}
diff --git a/tests/auto/qml/debugger/qqmlenginedebugservice/tst_qqmlenginedebugservice.cpp b/tests/auto/qml/debugger/qqmlenginedebugservice/tst_qqmlenginedebugservice.cpp
index ffde808bb4..467ebda91b 100644
--- a/tests/auto/qml/debugger/qqmlenginedebugservice/tst_qqmlenginedebugservice.cpp
+++ b/tests/auto/qml/debugger/qqmlenginedebugservice/tst_qqmlenginedebugservice.cpp
@@ -21,6 +21,7 @@
 #include <QtQml/qqmlexpression.h>
 #include <QtQml/qqmlproperty.h>
 #include <QtQml/qqmlincubator.h>
+#include <QtQml/qqmlapplicationengine.h>
 #include <QtQuick/qquickitem.h>
 
 #include <QtNetwork/qhostaddress.h>
@@ -161,6 +162,7 @@ private slots:
     void asynchronousCreate();
     void invalidContexts();
     void createObjectOnDestruction();
+    void fetchValueType();
 };
 
 QQmlEngineDebugObjectReference tst_QQmlEngineDebugService::findRootObject(
@@ -1358,6 +1360,26 @@ void tst_QQmlEngineDebugService::createObjectOnDestruction()
     QCOMPARE(spy.size(), 2);
 }
 
+void tst_QQmlEngineDebugService::fetchValueType()
+{
+    QQmlApplicationEngine engine;
+    engine.load(testFileUrl("fetchValueType.qml"));
+
+
+    bool success = false;
+    m_dbg->queryAvailableEngines(&success);
+    QVERIFY(success);
+    QVERIFY(QQmlDebugTest::waitForSignal(m_dbg, SIGNAL(result())));
+    QVERIFY(m_dbg->engines().size() > 1);
+
+    QQmlEngineDebugObjectReference object;
+    object.debugId = QQmlDebugService::idForObject(&engine);
+    m_dbg->queryObjectRecursive(object, &success);
+    QVERIFY(success);
+    QVERIFY(QQmlDebugTest::waitForSignal(m_dbg, SIGNAL(result())));
+
+}
+
 void tst_QQmlEngineDebugService::debuggerCrashOnAttach() {
     QQmlEngineDebugObjectReference obj = findRootObject(6);
     QVERIFY(!obj.className.isEmpty());