Replace remaining 0 with nullptr in Qt code

Also used type-appropriate enum values such as Qt::NoItemFlags in
some cases.

All cases identified via -Wzero-as-null-pointer-constant

Author: Empact

src/qt/addresstablemodel.cpp

@@ -300,8 +300,8 @@ QVariant AddressTableModel::headerData(int section, Qt::Orientation orientation,
 
 Qt::ItemFlags AddressTableModel::flags(const QModelIndex &index) const
 {
-    if(!index.isValid())
-        return 0;
+    if (!index.isValid()) return Qt::NoItemFlags;
+
     AddressTableEntry *rec = static_cast<AddressTableEntry*>(index.internalPointer());
 
     Qt::ItemFlags retval = Qt::ItemIsSelectable | Qt::ItemIsEnabled;

src/qt/bantablemodel.cpp

@@ -145,8 +145,7 @@ QVariant BanTableModel::headerData(int section, Qt::Orientation orientation, int
 
 Qt::ItemFlags BanTableModel::flags(const QModelIndex &index) const
 {
-    if(!index.isValid())
-        return 0;
+    if (!index.isValid()) return Qt::NoItemFlags;
 
     Qt::ItemFlags retval = Qt::ItemIsSelectable | Qt::ItemIsEnabled;
     return retval;

src/qt/bitcoin.cpp

@@ -243,15 +243,15 @@ void BitcoinApplication::createOptionsModel(bool resetSettings)
 
 void BitcoinApplication::createWindow(const NetworkStyle *networkStyle)
 {
-    window = new BitcoinGUI(m_node, platformStyle, networkStyle, 0);
+    window = new BitcoinGUI(m_node, platformStyle, networkStyle, nullptr);
 
     pollShutdownTimer = new QTimer(window);
     connect(pollShutdownTimer, &QTimer::timeout, window, &BitcoinGUI::detectShutdown);
 }
 
 void BitcoinApplication::createSplashScreen(const NetworkStyle *networkStyle)
 {
-    SplashScreen *splash = new SplashScreen(m_node, 0, networkStyle);
+    SplashScreen *splash = new SplashScreen(m_node, nullptr, 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.
     splash->show();
@@ -429,7 +429,7 @@ void BitcoinApplication::shutdownResult()
 
 void BitcoinApplication::handleRunawayException(const QString &message)
 {
-    QMessageBox::critical(0, "Runaway exception", BitcoinGUI::tr("A fatal error occurred. Bitcoin can no longer continue safely and will quit.") + QString("\n\n") + message);
+    QMessageBox::critical(nullptr, "Runaway exception", BitcoinGUI::tr("A fatal error occurred. Bitcoin can no longer continue safely and will quit.") + QString("\n\n") + message);
     ::exit(EXIT_FAILURE);
 }
 
@@ -503,7 +503,7 @@ int GuiMain(int argc, char* argv[])
     SetupUIArgs();
     std::string error;
     if (!node->parseParameters(argc, argv, error)) {
-        QMessageBox::critical(0, QObject::tr(PACKAGE_NAME),
+        QMessageBox::critical(nullptr, QObject::tr(PACKAGE_NAME),
             QObject::tr("Error parsing command line arguments: %1.").arg(QString::fromStdString(error)));
         return EXIT_FAILURE;
     }
@@ -540,12 +540,12 @@ int GuiMain(int argc, char* argv[])
     /// - Do not call GetDataDir(true) before this step finishes
     if (!fs::is_directory(GetDataDir(false)))
     {
-        QMessageBox::critical(0, QObject::tr(PACKAGE_NAME),
-                              QObject::tr("Error: Specified data directory \"%1\" does not exist.").arg(QString::fromStdString(gArgs.GetArg("-datadir", ""))));
+        QMessageBox::critical(nullptr, QObject::tr(PACKAGE_NAME),
+            QObject::tr("Error: Specified data directory \"%1\" does not exist.").arg(QString::fromStdString(gArgs.GetArg("-datadir", ""))));
         return EXIT_FAILURE;
     }
     if (!node->readConfigFiles(error)) {
-        QMessageBox::critical(0, QObject::tr(PACKAGE_NAME),
+        QMessageBox::critical(nullptr, QObject::tr(PACKAGE_NAME),
             QObject::tr("Error: Cannot parse configuration file: %1.").arg(QString::fromStdString(error)));
         return EXIT_FAILURE;
     }
@@ -560,7 +560,7 @@ int GuiMain(int argc, char* argv[])
     try {
         node->selectParams(gArgs.GetChainName());
     } catch(std::exception &e) {
-        QMessageBox::critical(0, QObject::tr(PACKAGE_NAME), QObject::tr("Error: %1").arg(e.what()));
+        QMessageBox::critical(nullptr, QObject::tr(PACKAGE_NAME), QObject::tr("Error: %1").arg(e.what()));
         return EXIT_FAILURE;
     }
 #ifdef ENABLE_WALLET

src/qt/bitcoinamountfield.cpp

@@ -196,7 +196,7 @@ class AmountSpinBox: public QAbstractSpinBox
         if (text().isEmpty()) // Allow step-up with empty field
             return StepUpEnabled;
 
-        StepEnabled rv = 0;
+        StepEnabled rv = StepNone;
         bool valid = false;
         CAmount val = value(&valid);
         if (valid) {
@@ -216,7 +216,7 @@ class AmountSpinBox: public QAbstractSpinBox
 
 BitcoinAmountField::BitcoinAmountField(QWidget *parent) :
     QWidget(parent),
-    amount(0)
+    amount(nullptr)
 {
     amount = new AmountSpinBox(this);
     amount->setLocale(QLocale::c());

src/qt/intro.cpp

@@ -226,7 +226,7 @@ bool Intro::pickDataDirectory(interfaces::Node& node)
                 }
                 break;
             } catch (const fs::filesystem_error&) {
-                QMessageBox::critical(0, tr(PACKAGE_NAME),
+                QMessageBox::critical(nullptr, tr(PACKAGE_NAME),
                     tr("Error: Specified data directory \"%1\" cannot be created.").arg(dataDir));
                 /* fall through, back to choosing screen */
             }
@@ -286,7 +286,7 @@ void Intro::on_dataDirectory_textChanged(const QString &dataDirStr)
 
 void Intro::on_ellipsisButton_clicked()
 {
-    QString dir = QDir::toNativeSeparators(QFileDialog::getExistingDirectory(0, "Choose data directory", ui->dataDirectory->text()));
+    QString dir = QDir::toNativeSeparators(QFileDialog::getExistingDirectory(nullptr, "Choose data directory", ui->dataDirectory->text()));
     if(!dir.isEmpty())
         ui->dataDirectory->setText(dir);
 }

src/qt/networkstyle.cpp

@@ -88,5 +88,5 @@ const NetworkStyle *NetworkStyle::instantiate(const QString &networkId)
                     network_styles[x].titleAddText);
         }
     }
-    return 0;
+    return nullptr;
 }

src/qt/paymentserver.cpp

@@ -223,7 +223,7 @@ PaymentServer::PaymentServer(QObject* parent, bool startLocalServer) :
 
         if (!uriServer->listen(name)) {
             // constructor is called early in init, so don't use "Q_EMIT message()" here
-            QMessageBox::critical(0, tr("Payment request error"),
+            QMessageBox::critical(nullptr, tr("Payment request error"),
                 tr("Cannot start bitcoin: click-to-pay handler"));
         }
         else {

src/qt/peertablemodel.cpp

@@ -96,15 +96,15 @@ class PeerTablePriv
         if (idx >= 0 && idx < cachedNodeStats.size())
             return &cachedNodeStats[idx];
 
-        return 0;
+        return nullptr;
     }
 };
 
 PeerTableModel::PeerTableModel(interfaces::Node& node, ClientModel *parent) :
     QAbstractTableModel(parent),
     m_node(node),
     clientModel(parent),
-    timer(0)
+    timer(nullptr)
 {
     columns << tr("NodeId") << tr("Node/Service") << tr("Ping") << tr("Sent") << tr("Received") << tr("User Agent");
     priv.reset(new PeerTablePriv());
@@ -197,8 +197,7 @@ QVariant PeerTableModel::headerData(int section, Qt::Orientation orientation, in
 
 Qt::ItemFlags PeerTableModel::flags(const QModelIndex &index) const
 {
-    if(!index.isValid())
-        return 0;
+    if (!index.isValid()) return Qt::NoItemFlags;
 
     Qt::ItemFlags retval = Qt::ItemIsSelectable | Qt::ItemIsEnabled;
     return retval;

src/qt/platformstyle.cpp

@@ -139,6 +139,6 @@ const PlatformStyle *PlatformStyle::instantiate(const QString &platformId)
                     platform_styles[x].useExtraSpacing);
         }
     }
-    return 0;
+    return nullptr;
 }
 

src/qt/qvalidatedlineedit.cpp

@@ -10,7 +10,7 @@
 QValidatedLineEdit::QValidatedLineEdit(QWidget *parent) :
     QLineEdit(parent),
     valid(true),
-    checkValidator(0)
+    checkValidator(nullptr)
 {
     connect(this, &QValidatedLineEdit::textChanged, this, &QValidatedLineEdit::markValid);
 }