gui: Drop ShutdownWindow dependency to BitcoinGUI

src/qt/utilitydialog.cpp

@@ -10,8 +10,6 @@
 
 #include <qt/forms/ui_helpmessagedialog.h>
 
-#include <qt/bitcoingui.h>
-
 #include <clientversion.h>
 #include <init.h>
 #include <util/system.h>
@@ -21,9 +19,10 @@
 
 #include <QCloseEvent>
 #include <QLabel>
+#include <QMainWindow>
 #include <QRegExp>
-#include <QTextTable>
 #include <QTextCursor>
+#include <QTextTable>
 #include <QVBoxLayout>
 
 /** "Help message" or "About" dialog box */
@@ -144,10 +143,9 @@ ShutdownWindow::ShutdownWindow(QWidget *parent, Qt::WindowFlags f):
     setLayout(layout);
 }
 
-QWidget *ShutdownWindow::showShutdownWindow(BitcoinGUI *window)
+QWidget* ShutdownWindow::showShutdownWindow(QMainWindow* window)
 {
-    if (!window)
-        return nullptr;
+    assert(window != nullptr);
 
     // Show a simple window indicating shutdown status
     QWidget *shutdownWindow = new ShutdownWindow();

src/qt/utilitydialog.h

@@ -6,9 +6,11 @@
 #define BITCOIN_QT_UTILITYDIALOG_H
 
 #include <QDialog>
-#include <QObject>
+#include <QWidget>
 
-class BitcoinGUI;
+QT_BEGIN_NAMESPACE
+class QMainWindow;
+QT_END_NAMESPACE
 
 namespace interfaces {
     class Node;
@@ -46,7 +48,7 @@ class ShutdownWindow : public QWidget
 
 public:
     explicit ShutdownWindow(QWidget *parent=nullptr, Qt::WindowFlags f=Qt::Widget);
-    static QWidget *showShutdownWindow(BitcoinGUI *window);
+    static QWidget* showShutdownWindow(QMainWindow* window);
 
 protected:
     void closeEvent(QCloseEvent *event);

test/lint/lint-circular-dependencies.sh

@@ -13,7 +13,6 @@ EXPECTED_CIRCULAR_DEPENDENCIES=(
     "index/txindex -> validation -> index/txindex"
     "policy/fees -> txmempool -> policy/fees"
     "qt/addresstablemodel -> qt/walletmodel -> qt/addresstablemodel"
-    "qt/bitcoingui -> qt/utilitydialog -> qt/bitcoingui"
     "qt/bitcoingui -> qt/walletframe -> qt/bitcoingui"
     "qt/bitcoingui -> qt/walletview -> qt/bitcoingui"
     "qt/clientmodel -> qt/peertablemodel -> qt/clientmodel"