Debugger: Initialize scoped context correctly

Initialize scopedContext with valid qmlContext. Otherwise debugger
crashes on attempt to lookup an object that includes a v4Function
property

Pick-to: 6.2 6.4
Fixes: QTBUG-107607
Change-Id: Iea59bdf9d379a5415abe1767f76f851978b1be3f
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

5 files changed, 97 insertions, 4 deletions

diff --git a/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp b/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp
index 383668833b..6ed24f29d1 100644
--- a/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp
+++ b/src/plugins/qmltooling/qmldbg_debugger/qv4debugjob.cpp
@@ -175,8 +175,8 @@ void ValueLookupJob::run()
     QScopedPointer<QObject> scopeObject;
     QV4::ExecutionEngine *engine = collector->engine();
     QV4::Scope scope(engine);
-    QV4::Heap::ExecutionContext *qmlContext = nullptr;
-    if (engine->qmlEngine() && !engine->qmlContext()) {
+    QV4::Heap::ExecutionContext *qmlContext = engine->qmlContext();
+    if (engine->qmlEngine() && !qmlContext) {
         scopeObject.reset(new QObject);
         qmlContext = QV4::QmlContext::create(engine->currentContext(),
                                 QQmlContextData::get(engine->qmlEngine()->rootContext()),
diff --git a/tests/auto/qml/debugger/qv4debugger/CMakeLists.txt b/tests/auto/qml/debugger/qv4debugger/CMakeLists.txt
index 4d45ecdd1a..519acaedff 100644
--- a/tests/auto/qml/debugger/qv4debugger/CMakeLists.txt
+++ b/tests/auto/qml/debugger/qv4debugger/CMakeLists.txt
@@ -13,6 +13,17 @@ file(GLOB_RECURSE test_data_glob
         data/*)
 list(APPEND test_data ${test_data_glob})
 
+qt_add_library(testCppTypes STATIC)
+qt_autogen_tools_initial_setup(testCppTypes)
+target_link_libraries(testCppTypes PRIVATE Qt::Qml Qt::QmlPrivate Qt::Quick)
+
+qt6_add_qml_module(testCppTypes
+    VERSION 1.0
+    URI TestTypes
+    SOURCES
+        commontypes.h
+)
+
 qt_internal_add_test(tst_qv4debugger
     SOURCES
         ../../../../../src/plugins/qmltooling/qmldbg_debugger/qv4datacollector.cpp ../../../../../src/plugins/qmltooling/qmldbg_debugger/qv4datacollector.h
@@ -28,6 +39,7 @@ qt_internal_add_test(tst_qv4debugger
         Qt::Network
         Qt::QmlPrivate
         Qt::QuickTestUtilsPrivate
+        testCppTypesplugin
     TESTDATA ${test_data}
 )
 
diff --git a/tests/auto/qml/debugger/qv4debugger/commontypes.h b/tests/auto/qml/debugger/qv4debugger/commontypes.h
new file mode 100644
index 0000000000..01b2125ae3
--- /dev/null
+++ b/tests/auto/qml/debugger/qv4debugger/commontypes.h
@@ -0,0 +1,20 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#ifndef COMMONTYPES_H
+#define COMMONTYPES_H
+
+#include <QtQuick/qquickitem.h>
+#include <QtQml/qqmlregistration.h>
+#include <QtQml/private/qv4engine_p.h>
+
+class MyType : public QQuickItem
+{
+    Q_OBJECT
+    QML_ELEMENT
+public:
+    MyType(QQuickItem *parent = nullptr) : QQuickItem(parent) {}
+    Q_INVOKABLE void name(QQmlV4Function*) const {}
+};
+
+#endif // COMMONTYPES_H
diff --git a/tests/auto/qml/debugger/qv4debugger/data/qtbug_107607.qml b/tests/auto/qml/debugger/qv4debugger/data/qtbug_107607.qml
new file mode 100644
index 0000000000..a7758de8a8
--- /dev/null
+++ b/tests/auto/qml/debugger/qv4debugger/data/qtbug_107607.qml
@@ -0,0 +1,10 @@
+import QtQuick
+import TestTypes
+MyType {
+    objectName: "patron"
+    Item {
+        Component.onCompleted: {
+            console.log("Hallo Welt");
+        }
+    }
+}
\ No newline at end of file
diff --git a/tests/auto/qml/debugger/qv4debugger/tst_qv4debugger.cpp b/tests/auto/qml/debugger/qv4debugger/tst_qv4debugger.cpp
index cdb7b1dee0..6f147446f0 100644
--- a/tests/auto/qml/debugger/qv4debugger/tst_qv4debugger.cpp
+++ b/tests/auto/qml/debugger/qv4debugger/tst_qv4debugger.cpp
@@ -16,10 +16,13 @@
 #include <private/qv4string_p.h>
 #include <private/qqmlbuiltinfunctions_p.h>
 #include <private/qqmldebugservice_p.h>
+#include <QtQml/qqmlextensionplugin.h>
 
 using namespace QV4;
 using namespace QV4::Debugging;
 
+Q_IMPORT_QML_PLUGIN(TestTypesPlugin);
+
 typedef QV4::ReturnedValue (*InjectedFunction)(const FunctionObject *b, const QV4::Value *, const QV4::Value *, int);
 Q_DECLARE_METATYPE(InjectedFunction)
 
@@ -176,7 +179,15 @@ public slots:
             ExpressionEvalJob job(debugger->engine(), request.frameNr, request.context,
                                   request.expression, &collector);
             debugger->runInEngine(&job);
-            m_expressionResults << job.returnValue();
+            const QJsonObject& result = job.returnValue();
+            m_expressionResults << result;
+
+            if (request.shouldLookup) {
+                QJsonArray handles {result.value("handle").toInt()};
+                ValueLookupJob job(handles, &collector);
+                debugger->runInEngine(&job);
+                m_lookupResults << job.returnValue();
+            }
         }
 
         if (m_captureContextInfo)
@@ -249,10 +260,14 @@ public:
         QString expression;
         int frameNr;
         int context;
+        bool shouldLookup = false;
     };
+
+
     QVector<ExpressionRequest> m_expressionRequests;
     QV4Debugger::Speed m_resumeSpeed;
     QList<QJsonObject> m_expressionResults;
+    QList<QJsonObject> m_lookupResults;
     QV4Debugger *m_debugger;
 
     // Utility methods:
@@ -306,7 +321,7 @@ private slots:
 
     void readThis();
     void signalParameters();
-
+    void debuggerNoCrash();
 private:
     QV4Debugger *debugger() const
     {
@@ -916,6 +931,42 @@ void tst_qv4debugger::signalParameters()
     QCOMPARE(obj->property("resultCallbackExternal").toString(), QLatin1String("unset"));
 }
 
+void tst_qv4debugger::debuggerNoCrash()
+{
+    QQmlEngine engine;
+    QV4::ExecutionEngine *v4 = engine.handle();
+    QPointer<QV4Debugger> v4Debugger = new QV4Debugger(v4);
+    v4->setDebugger(v4Debugger.data());
+
+    QScopedPointer<QThread> debugThread(new QThread);
+    debugThread->start();
+    QScopedPointer<TestAgent> debuggerAgent(new TestAgent(v4));
+    debuggerAgent->addDebugger(v4Debugger);
+    debuggerAgent->moveToThread(debugThread.data());
+
+    const QString qmlFileName("qtbug_107607.qml");
+    const QString qmlFilePath(testFile(qmlFileName));
+    QQmlComponent component(&engine, qmlFilePath);
+
+    TestAgent::ExpressionRequest request;
+    request.expression = "this.parent";
+    request.frameNr = 0;
+    request.context = -1;
+    request.shouldLookup = true;
+    debuggerAgent->m_expressionRequests << request;
+    v4Debugger->addBreakPoint(qmlFileName, 7);
+
+    QScopedPointer<QObject> obj(component.create());
+
+    QVERIFY(debuggerAgent->m_lookupResults.size() > 0);
+    const QJsonObject result = debuggerAgent->m_lookupResults[0];
+    const QJsonArray properties = result["0"].toObject().value("properties").toArray();
+    QCOMPARE(properties[0].toObject().value("value").toString(), QStringLiteral("patron"));
+
+    debugThread->quit();
+    debugThread->wait();
+}
+
 tst_qv4debugger::tst_qv4debugger() : QQmlDataTest(QT_QMLTEST_DATADIR) { }
 
 QTEST_MAIN(tst_qv4debugger)