refactor: Remove SplashScreen::setNode method

Make m_node a reference instead of pointer, now that it can no longer be null,
as suggested
bitcoin/bitcoin#15936 (comment)

Author: vasild

src/qt/bitcoin.cpp

@@ -280,8 +280,7 @@ void BitcoinApplication::createWindow(const NetworkStyle *networkStyle)
 void BitcoinApplication::createSplashScreen(const NetworkStyle *networkStyle)
 {
     assert(!m_splash);
-    m_splash = new SplashScreen(networkStyle);
-    m_splash->setNode(node());
+    m_splash = new SplashScreen(node(), networkStyle);
     // We don't hold a direct pointer to the splash screen after creation, but the splash
     // screen will take care of deleting itself when finish() happens.
     m_splash->show();

src/qt/splashscreen.cpp

@@ -27,8 +27,8 @@
 #include <QScreen>
 
 
-SplashScreen::SplashScreen(const NetworkStyle* networkStyle)
-    : QWidget(), curAlignment(0)
+SplashScreen::SplashScreen(interfaces::Node& node, const NetworkStyle* networkStyle)
+    : QWidget(), curAlignment(0), m_node{node}
 {
     // set reference point, paddings
     int paddingRight            = 50;
@@ -130,25 +130,19 @@ SplashScreen::SplashScreen(const NetworkStyle* networkStyle)
     installEventFilter(this);
 
     GUIUtil::handleCloseWindowShortcut(this);
-}
 
-SplashScreen::~SplashScreen()
-{
-    if (m_node) unsubscribeFromCoreSignals();
+    subscribeToCoreSignals();
 }
 
-void SplashScreen::setNode(interfaces::Node& node)
+SplashScreen::~SplashScreen()
 {
-    assert(!m_node);
-    m_node = &node;
-    subscribeToCoreSignals();
-    if (m_shutdown) m_node->startShutdown();
+    unsubscribeFromCoreSignals();
 }
 
 void SplashScreen::shutdown()
 {
     m_shutdown = true;
-    if (m_node) m_node->startShutdown();
+    m_node.startShutdown();
 }
 
 bool SplashScreen::eventFilter(QObject * obj, QEvent * ev) {
@@ -192,16 +186,16 @@ static void ShowProgress(SplashScreen *splash, const std::string &title, int nPr
 void SplashScreen::subscribeToCoreSignals()
 {
     // Connect signals to client
-    m_handler_init_message = m_node->handleInitMessage(std::bind(InitMessage, this, std::placeholders::_1));
-    m_handler_show_progress = m_node->handleShowProgress(std::bind(ShowProgress, this, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3));
-    m_handler_init_wallet = m_node->handleInitWallet([this]() { handleLoadWallet(); });
+    m_handler_init_message = m_node.handleInitMessage(std::bind(InitMessage, this, std::placeholders::_1));
+    m_handler_show_progress = m_node.handleShowProgress(std::bind(ShowProgress, this, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3));
+    m_handler_init_wallet = m_node.handleInitWallet([this]() { handleLoadWallet(); });
 }
 
 void SplashScreen::handleLoadWallet()
 {
 #ifdef ENABLE_WALLET
     if (!WalletModel::isWalletEnabled()) return;
-    m_handler_load_wallet = m_node->walletLoader().handleLoadWallet([this](std::unique_ptr<interfaces::Wallet> wallet) {
+    m_handler_load_wallet = m_node.walletLoader().handleLoadWallet([this](std::unique_ptr<interfaces::Wallet> wallet) {
         m_connected_wallet_handlers.emplace_back(wallet->handleShowProgress(std::bind(ShowProgress, this, std::placeholders::_1, std::placeholders::_2, false)));
         m_connected_wallets.emplace_back(std::move(wallet));
     });

src/qt/splashscreen.h

@@ -28,9 +28,8 @@ class SplashScreen : public QWidget
     Q_OBJECT
 
 public:
-    explicit SplashScreen(const NetworkStyle *networkStyle);
+    explicit SplashScreen(interfaces::Node& node, const NetworkStyle* networkStyle);
     ~SplashScreen();
-    void setNode(interfaces::Node& node);
 
 protected:
     void paintEvent(QPaintEvent *event) override;
@@ -62,7 +61,7 @@ public Q_SLOTS:
     QColor curColor;
     int curAlignment;
 
-    interfaces::Node* m_node = nullptr;
+    interfaces::Node& m_node;
     bool m_shutdown = false;
     std::unique_ptr<interfaces::Handler> m_handler_init_message;
     std::unique_ptr<interfaces::Handler> m_handler_show_progress;