Debugger: Fix crash when shutting down during core initialization

GDB output is still processed, but the docks are already deleted.

Use asynchronous shutdown, and wait for engine termination before deleting
the main window.

Change-Id: I28a36de15a0e9ce08ae18412d97aaf13cb0c25a6
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/debugger/debuggerplugin.cpp

@@ -637,6 +637,7 @@ public:
     bool initialize(const QStringList &arguments, QString *errorMessage);
     void extensionsInitialized();
     void aboutToShutdown();
+    void doShutdown();
 
     void connectEngine(DebuggerRunTool *runTool);
     void disconnectEngine() { connectEngine(0); }
@@ -763,8 +764,6 @@ public:
     void aboutToUnloadSession();
     void aboutToSaveSession();
 
-    void coreShutdown();
-
 public:
     void updateDebugActions();
 
@@ -1050,6 +1049,7 @@ public:
     DebuggerPlugin *m_plugin = 0;
 
     SnapshotHandler *m_snapshotHandler = 0;
+    QTimer m_shutdownTimer;
     bool m_shuttingDown = false;
     QPointer<DebuggerEngine> m_previouslyActiveEngine;
     QPointer<DebuggerRunTool> m_currentRunTool;
@@ -1319,8 +1319,6 @@ bool DebuggerPluginPrivate::initialize(const QStringList &arguments,
     m_debuggerSettings = new DebuggerSettings;
     m_debuggerSettings->readSettings();
 
-    connect(ICore::instance(), &ICore::coreAboutToClose, this, &DebuggerPluginPrivate::coreShutdown);
-
     const Context cppDebuggercontext(C_CPPDEBUGGER);
     const Context qmljsDebuggercontext(C_QMLDEBUGGER);
 
@@ -2796,13 +2794,23 @@ void DebuggerPluginPrivate::showStatusMessage(const QString &msg0, int timeout)
     m_mainWindow->showStatusMessage(msg, timeout);
 }
 
-void DebuggerPluginPrivate::coreShutdown()
+void DebuggerPluginPrivate::aboutToShutdown()
 {
     m_shuttingDown = true;
-    if (currentEngine()) {
+
-        if (currentEngine()->state() != Debugger::DebuggerNotReady)
+    disconnect(SessionManager::instance(), &SessionManager::startupProjectChanged, this, nullptr);
-            currentEngine()->abortDebugger();
+
+    m_mainWindow->saveCurrentPerspective();
+    m_shutdownTimer.setInterval(0);
+    m_shutdownTimer.setSingleShot(true);
+    connect(&m_shutdownTimer, &QTimer::timeout, this, &DebuggerPluginPrivate::doShutdown);
+    if (DebuggerEngine *engine = currentEngine()) {
+        if (engine->state() != Debugger::DebuggerNotReady) {
+            engine->abortDebugger();
+            m_shutdownTimer.setInterval(3000);
+        }
     }
+    m_shutdownTimer.start();
 }
 
 const CPlusPlus::Snapshot &cppCodeModelSnapshot()
@@ -2938,11 +2946,13 @@ void DebuggerPluginPrivate::runControlFinished(DebuggerRunTool *runTool)
 {
     if (runTool && runTool->engine())
         runTool->engine()->handleFinished();
-    if (m_shuttingDown)
-        return;
     showStatusMessage(tr("Debugger finished."));
     m_snapshotHandler->removeSnapshot(runTool);
     if (m_snapshotHandler->size() == 0) {
+        if (m_shuttingDown) {
+            doShutdown();
+            return;
+        }
         // Last engine quits.
         disconnectEngine();
         if (boolSetting(SwitchModeOnExit))
@@ -3120,11 +3130,9 @@ void showModuleSections(const QString &moduleName, const Sections &sections)
     createNewDock(w);
 }
 
-void DebuggerPluginPrivate::aboutToShutdown()
+void DebuggerPluginPrivate::doShutdown()
 {
-    disconnect(SessionManager::instance(), &SessionManager::startupProjectChanged, this, nullptr);
+    m_shutdownTimer.stop();
-
-    m_mainWindow->saveCurrentPerspective();
     delete m_mainWindow;
     m_mainWindow = 0;
 
@@ -3140,6 +3148,7 @@ void DebuggerPluginPrivate::aboutToShutdown()
 
     delete m_mode;
     m_mode = 0;
+    emit m_plugin->asynchronousShutdownFinished();
 }
 
 void updateState(DebuggerRunTool *runTool)
@@ -3302,7 +3311,7 @@ IPlugin::ShutdownFlag DebuggerPlugin::aboutToShutdown()
 {
     removeObject(this);
     dd->aboutToShutdown();
-    return SynchronousShutdown;
+    return AsynchronousShutdown;
 }
 
 QObject *DebuggerPlugin::remoteCommand(const QStringList &options,