Merge #605: Delete splash screen widget early

1b22849 qt: Drop no longer used `SplashScreen::finish()` slot (Hennadii Stepanov)
10811af qt: Drop no longer used `BitcoinApplication::splashFinished()` signal (Hennadii Stepanov)
5299cfe qt: Delete splash screen widget explicitly (Hennadii Stepanov)

Pull request description:

  Fixes #604.
  Fixes bitcoin/bitcoin#25146.
  Fixes bitcoin/bitcoin#26340.

  `SplashScreen::deleteLater()` [does not guarantee](https://doc.qt.io/qt-5/qobject.html#deleteLater) deletion of the `m_splash` object prior to the wallet context deletion. If the latter happens first, the [segfault](#604 (comment)) follows.

ACKs for top commit:
  dooglus:
    ACK 1b22849
  furszy:
    ACK 1b22849
  john-moffett:
    ACK 1b22849

Tree-SHA512: bb01d0bf2051f5b184dc415c4f5d32dfb7b8bd772feff7ec7754ded4c6482de27f004b9712df7d53c5ee82e153f48aef4372e4a49d7bcbbb137f73e9b4947962

Author: hebasto

src/qt/bitcoin.cpp

@@ -311,11 +311,7 @@ void BitcoinApplication::createSplashScreen(const NetworkStyle *networkStyle)
 {
     assert(!m_splash);
     m_splash = new SplashScreen(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();
-    connect(this, &BitcoinApplication::splashFinished, m_splash, &SplashScreen::finish);
-    connect(this, &BitcoinApplication::requestedShutdown, m_splash, &QWidget::close);
 }
 
 void BitcoinApplication::createNode(interfaces::Init& init)
@@ -373,6 +369,9 @@ void BitcoinApplication::requestShutdown()
         w->hide();
     }
 
+    delete m_splash;
+    m_splash = nullptr;
+
     // Show a simple window indicating shutdown status
     // Do this first as some of the steps may take some time below,
     // for example the RPC console may still be executing a command.
@@ -412,10 +411,13 @@ void BitcoinApplication::requestShutdown()
 void BitcoinApplication::initializeResult(bool success, interfaces::BlockAndHeaderTipInfo tip_info)
 {
     qDebug() << __func__ << ": Initialization result: " << success;
+
     // Set exit result.
     returnValue = success ? EXIT_SUCCESS : EXIT_FAILURE;
-    if(success)
-    {
+    if(success) {
+        delete m_splash;
+        m_splash = nullptr;
+
         // Log this only after AppInitMain finishes, as then logging setup is guaranteed complete
         qInfo() << "Platform customization:" << platformStyle->getName();
         clientModel = new ClientModel(node(), optionsModel);
@@ -438,7 +440,6 @@ void BitcoinApplication::initializeResult(bool success, interfaces::BlockAndHead
         } else {
             window->showMinimized();
         }
-        Q_EMIT splashFinished();
         Q_EMIT windowShown(window);
 
 #ifdef ENABLE_WALLET
@@ -455,7 +456,6 @@ void BitcoinApplication::initializeResult(bool success, interfaces::BlockAndHead
 #endif
         pollShutdownTimer->start(SHUTDOWN_POLLING_DELAY);
     } else {
-        Q_EMIT splashFinished(); // Make sure splash screen doesn't stick around during shutdown
         requestShutdown();
     }
 }

src/qt/bitcoin.h

@@ -89,7 +89,6 @@ public Q_SLOTS:
 Q_SIGNALS:
     void requestedInitialize();
     void requestedShutdown();
-    void splashFinished();
     void windowShown(BitcoinGUI* window);
 
 protected:

src/qt/splashscreen.cpp

@@ -161,16 +161,6 @@ bool SplashScreen::eventFilter(QObject * obj, QEvent * ev) {
     return QObject::eventFilter(obj, ev);
 }
 
-void SplashScreen::finish()
-{
-    /* If the window is minimized, hide() will be ignored. */
-    /* Make sure we de-minimize the splashscreen window before hiding */
-    if (isMinimized())
-        showNormal();
-    hide();
-    deleteLater(); // No more need for this
-}
-
 static void InitMessage(SplashScreen *splash, const std::string &message)
 {
     bool invoked = QMetaObject::invokeMethod(splash, "showMessage",

src/qt/splashscreen.h

@@ -37,9 +37,6 @@ class SplashScreen : public QWidget
     void closeEvent(QCloseEvent *event) override;
 
 public Q_SLOTS:
-    /** Hide the splash screen window and schedule the splash screen object for deletion */
-    void finish();
-
     /** Show message and progress */
     void showMessage(const QString &message, int alignment, const QColor &color);