QmlDesigner: modernize code

- no behavior changes
 - moved a slot to a lambda
 - Using QPointer instead of raw pointer to trigger
   assert if dangling pointer is accessed.
   Refactoring the code might accidentally trigger a
   delete of the QWidget.

Change-Id: Idf711da92e13cf81dd718ae9e034bca7f6d26220
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@theqtcompany.com>

src/plugins/qmldesigner/designmodewidget.cpp

@@ -123,20 +123,17 @@ QList<QToolButton *> DesignerSideBarItem::createToolBarWidgets()
 }
 
 // ---------- DesignModeWidget
-DesignModeWidget::DesignModeWidget(QWidget *parent) :
-    QWidget(parent),
-    m_mainSplitter(0),
-    m_toolBar(new Core::EditorToolBar(this)),
-    m_crumbleBar(new CrumbleBar(this)),
-    m_isDisabled(false),
-    m_showSidebars(true),
-    m_initStatus(NotInitialized),
-    m_warningWidget(0),
-    m_navigatorHistoryCounter(-1),
-    m_keepNavigatorHistory(false)
+DesignModeWidget::DesignModeWidget(QWidget *parent)
+    : QWidget(parent)
+    , m_toolBar(new Core::EditorToolBar(this))
+    , m_crumbleBar(new CrumbleBar(this))
 {
     connect(viewManager().nodeInstanceView(), &NodeInstanceView::qmlPuppetCrashed,
-        this, &DesignModeWidget::showQmlPuppetCrashedError);
+        [=]() {
+            RewriterError error(tr("Qt Quick emulation layer crashed"));
+            updateErrorStatus(QList<RewriterError>() << error);
+        }
+    );
 }
 
 DesignModeWidget::~DesignModeWidget()
@@ -275,9 +272,9 @@ void DesignModeWidget::setup()
     QList<Core::INavigationWidgetFactory *> factories =
             ExtensionSystem::PluginManager::getObjects<Core::INavigationWidgetFactory>();
 
-    QWidget *openDocumentsWidget = 0;
-    QWidget *projectsExplorer = 0;
-    QWidget *fileSystemExplorer = 0;
+    QWidget *openDocumentsWidget = nullptr;
+    QWidget *projectsExplorer = nullptr;
+    QWidget *fileSystemExplorer = nullptr;
 
     foreach (Core::INavigationWidgetFactory *factory, factories) {
         Core::NavigationView navigationView;
@@ -414,16 +411,6 @@ void DesignModeWidget::setup()
     show();
 }
 
-void DesignModeWidget::showQmlPuppetCrashedError()
-{
-    QList<RewriterError> errorList;
-    RewriterError error(tr("Qt Quick emulation layer crashed"));
-    errorList.append(error);
-
-    disableWidgets();
-    showMessageBox(errorList);
-}
-
 void DesignModeWidget::toolBarOnGoBackClicked()
 {
     if (m_navigatorHistoryCounter > 0) {

src/plugins/qmldesigner/designmodewidget.h

@@ -89,8 +89,6 @@ public slots:
     void toggleRightSidebar();
 
 private slots:
-    void showQmlPuppetCrashedError();
-
     void toolBarOnGoBackClicked();
     void toolBarOnGoForwardClicked();
 
@@ -107,21 +105,21 @@ private: // functions
 
 private: // variables
     QSplitter *m_mainSplitter = nullptr;
-    DocumentWarningWidget *m_warningWidget = nullptr;
+    QPointer<DocumentWarningWidget> m_warningWidget;
 
     QScopedPointer<Core::SideBar> m_leftSideBar;
     QScopedPointer<Core::SideBar> m_rightSideBar;
     QPointer<QWidget> m_topSideBar;
     Core::EditorToolBar *m_toolBar;
     CrumbleBar *m_crumbleBar;
-    bool m_isDisabled;
-    bool m_showSidebars;
+    bool m_isDisabled = false;
+    bool m_showSidebars = true;
 
-    InitializeStatus m_initStatus;
+    InitializeStatus m_initStatus = NotInitialized;
 
     QStringList m_navigatorHistory;
-    int m_navigatorHistoryCounter;
-    bool m_keepNavigatorHistory;
+    int m_navigatorHistoryCounter = -1;
+    bool m_keepNavigatorHistory = false;
 
     QList<QPointer<QWidget> >m_viewWidgets;
 };