Merge #6609: backport: bitcoin-core/gui#693: Fix segfault when shutdown during wallet open

138e4fa Merge bitcoin-core/gui#693: Fix segfault when shutdown during wallet open (Hennadii Stepanov)

Pull request description:

  ## Issue being fixed or feature implemented
  Pls see the original PR description + fixes dashpay/dash#6569 (comment)

  ## What was done?
  backport bitcoin-core/gui#693

  ## How Has This Been Tested?
  Run `./src/qt/dash-qt`

  ## Breaking Changes
  n/a

  ## Checklist:
  - [ ] I have performed a self-review of my own code
  - [ ] I have commented my code, particularly in hard-to-understand areas
  - [ ] I have added or updated relevant unit/integration/functional/e2e tests
  - [ ] I have made corresponding changes to the documentation
  - [ ] I have assigned this pull request to a milestone _(for repository code-owners and collaborators only)_

ACKs for top commit:
  PastaPastaPasta:
    utACK 138e4fa

Tree-SHA512: 2ac5bf14f21626c5c5434f3f32d892d58d22da7a633558a0af2a56a1c63ef999d43a74c5c0fac8710ba1ad3927fd3021455707c715b72f6d25812d001463e17c

Author: PastaPastaPasta

src/qt/bitcoingui.cpp

@@ -899,6 +899,10 @@ void BitcoinGUI::setWalletController(WalletController* wallet_controller)
 
     GUIUtil::ExceptionSafeConnect(wallet_controller, &WalletController::walletAdded, this, &BitcoinGUI::addWallet);
     connect(wallet_controller, &WalletController::walletRemoved, this, &BitcoinGUI::removeWallet);
+    connect(wallet_controller, &WalletController::destroyed, this, [this] {
+        // wallet_controller gets destroyed manually, but it leaves our member copy dangling
+        m_wallet_controller = nullptr;
+    });
 
     auto activity = new LoadWalletsActivity(m_wallet_controller, this);
     activity->load();
@@ -911,7 +915,7 @@ WalletController* BitcoinGUI::getWalletController()
 
 void BitcoinGUI::addWallet(WalletModel* walletModel)
 {
-    if (!walletFrame) return;
+    if (!walletFrame || !m_wallet_controller) return;
 
     WalletView* wallet_view = new WalletView(walletModel, walletFrame);
     if (!walletFrame->addView(wallet_view)) return;
@@ -959,7 +963,7 @@ void BitcoinGUI::removeWallet(WalletModel* walletModel)
 
 void BitcoinGUI::setCurrentWallet(WalletModel* wallet_model)
 {
-    if (!walletFrame) return;
+    if (!walletFrame || !m_wallet_controller) return;
     walletFrame->setCurrentWallet(wallet_model);
     for (int index = 0; index < m_wallet_selector->count(); ++index) {
         if (m_wallet_selector->itemData(index).value<WalletModel*>() == wallet_model) {

src/qt/sendcoinsdialog.cpp

@@ -604,10 +604,15 @@ SendCoinsEntry *SendCoinsDialog::addEntry()
     entry->clear();
     entry->setFocus();
     ui->scrollAreaWidgetContents->resize(ui->scrollAreaWidgetContents->sizeHint());
-    qApp->processEvents();
-    QScrollBar* bar = ui->scrollArea->verticalScrollBar();
-    if(bar)
-        bar->setSliderPosition(bar->maximum());
+
+    // Scroll to the newly added entry on a QueuedConnection because Qt doesn't
+    // adjust the scroll area and scrollbar immediately when the widget is added.
+    // Invoking on a DirectConnection will only scroll to the second-to-last entry.
+    QMetaObject::invokeMethod(ui->scrollArea, [this] {
+        if (ui->scrollArea->verticalScrollBar()) {
+            ui->scrollArea->verticalScrollBar()->setValue(ui->scrollArea->verticalScrollBar()->maximum());
+        }
+    }, Qt::QueuedConnection);
 
     updateTabsAndLabels();
     return entry;

src/qt/test/wallettests.cpp

@@ -163,6 +163,8 @@ void TestGUI(interfaces::Node& node)
     QCOMPARE(transactionTableModel->rowCount({}), 105);
     uint256 txid1 = SendCoins(*wallet.get(), sendCoinsDialog, PKHash(), 5 * COIN);
     uint256 txid2 = SendCoins(*wallet.get(), sendCoinsDialog, PKHash(), 10 * COIN);
+    // Transaction table model updates on a QueuedConnection, so process events to ensure it's updated.
+    qApp->processEvents();
     QCOMPARE(transactionTableModel->rowCount({}), 107);
     QVERIFY(FindTx(*transactionTableModel, txid1).isValid());
     QVERIFY(FindTx(*transactionTableModel, txid2).isValid());