Copilot: shutdown plugin asynchronously

Wait for the client to finish. This fixes a crash when running the
plugin unit tests of the copilot plugin.

Change-Id: Id0805cb628a79316cd904350bb159ff1369a03b9
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/copilot/copilotplugin.cpp

@@ -60,5 +60,13 @@ void CopilotPlugin::restartClient()
                                  CopilotSettings::instance().distPath());
 }
 
+ExtensionSystem::IPlugin::ShutdownFlag CopilotPlugin::aboutToShutdown()
+{
+    if (!m_client)
+        return SynchronousShutdown;
+    connect(m_client, &QObject::destroyed, this, &IPlugin::asynchronousShutdownFinished);
+    return AsynchronousShutdown;
+}
+
 } // namespace Internal
 } // namespace Copilot

src/plugins/copilot/copilotplugin.h

@@ -21,6 +21,7 @@ public:
     void initialize() override;
     void extensionsInitialized() override;
     void restartClient();
+    ShutdownFlag aboutToShutdown() override;
 
 private:
     QPointer<CopilotClient> m_client;

src/plugins/languageclient/languageclientmanager.cpp

@@ -237,7 +237,13 @@ void LanguageClientManager::deleteClient(Client *client)
     managerInstance->m_clients.removeAll(client);
     for (QList<Client *> &clients : managerInstance->m_clientsForSetting)
         clients.removeAll(client);
-    client->deleteLater();
+
+    // a deleteLater is not sufficient here as it pastes the delete later event at the end
+    // of the main event loop and when the plugins are shutdown we spawn an additional eventloop
+    // that will not handle the delete later event. Use invokeMethod with Qt::QueuedConnection
+    // instead.
+    QMetaObject::invokeMethod(client, [client] {delete client;}, Qt::QueuedConnection);
+
     if (!PluginManager::isShuttingDown())
         emit instance()->clientRemoved(client);
 }