Merge #15114: Qt: Replace remaining 0 with nullptr

3a0e76f Replace remaining 0 with nullptr in Qt code (Ben Woosley)
9096276 Don't use zero as null pointer constant (-Wzero-as-null-pointer-constant) (practicalswift)

Pull request description:

  This corrects all violations of `-Wzero-as-null-pointer-constant` identified in the Qt codebase.

  These changes are extracted from #15112 as suggested by @MarcoFalke to ease review. This is in service of enabling `-Wzero-as-null-pointer-constant`, which should eliminate this as a concern going forward.

  Note there are 2 non-Qt changes: `src/test/allocator_tests.cpp` and `src/wallet/db.cpp`.

Tree-SHA512: 206bd668802147ba42bc413c2d7d259cb59aca9ec1da74a6bf2ca3932e60ae492faacbc61bcee0fd6b4b49a4d59d075b7e5404f0526b36c47718f9b0587e7768

Author: laanwj

src/qt/addressbookpage.cpp

@@ -59,7 +59,7 @@ class AddressBookSortFilterProxyModel final : public QSortFilterProxyModel
 AddressBookPage::AddressBookPage(const PlatformStyle *platformStyle, Mode _mode, Tabs _tab, QWidget *parent) :
     QDialog(parent),
     ui(new Ui::AddressBookPage),
-    model(0),
+    model(nullptr),
     mode(_mode),
     tab(_tab)
 {

src/qt/addressbookpage.h

@@ -38,7 +38,7 @@ class AddressBookPage : public QDialog
         ForEditing  /**< Open address book for editing */
     };
 
-    explicit AddressBookPage(const PlatformStyle *platformStyle, Mode mode, Tabs tab, QWidget *parent = 0);
+    explicit AddressBookPage(const PlatformStyle *platformStyle, Mode mode, Tabs tab, QWidget *parent = nullptr);
     ~AddressBookPage();
 
     void setModel(AddressTableModel *model);

src/qt/addresstablemodel.cpp

@@ -153,7 +153,7 @@ class AddressTablePriv
         }
         else
         {
-            return 0;
+            return nullptr;
         }
     }
 };
@@ -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/addresstablemodel.h

@@ -25,7 +25,7 @@ class AddressTableModel : public QAbstractTableModel
     Q_OBJECT
 
 public:
-    explicit AddressTableModel(WalletModel *parent = 0);
+    explicit AddressTableModel(WalletModel *parent = nullptr);
     ~AddressTableModel();
 
     enum ColumnIndex {

src/qt/askpassphrasedialog.cpp

@@ -22,7 +22,7 @@ AskPassphraseDialog::AskPassphraseDialog(Mode _mode, QWidget *parent) :
     QDialog(parent),
     ui(new Ui::AskPassphraseDialog),
     mode(_mode),
-    model(0),
+    model(nullptr),
     fCapsLock(false)
 {
     ui->setupUi(this);

src/qt/bantablemodel.cpp

@@ -76,7 +76,7 @@ class BanTablePriv
         if (idx >= 0 && idx < cachedBanlist.size())
             return &cachedBanlist[idx];
 
-        return 0;
+        return nullptr;
     }
 };
 
@@ -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/bantablemodel.h

@@ -45,7 +45,7 @@ class BanTableModel : public QAbstractTableModel
     Q_OBJECT
 
 public:
-    explicit BanTableModel(interfaces::Node& node, ClientModel *parent = 0);
+    explicit BanTableModel(interfaces::Node& node, ClientModel *parent = nullptr);
     ~BanTableModel();
     void startAutoRefresh();
     void stopAutoRefresh();

src/qt/bitcoin.cpp

@@ -178,18 +178,18 @@ void BitcoinCore::shutdown()
 
 BitcoinApplication::BitcoinApplication(interfaces::Node& node, int &argc, char **argv):
     QApplication(argc, argv),
-    coreThread(0),
+    coreThread(nullptr),
     m_node(node),
-    optionsModel(0),
-    clientModel(0),
-    window(0),
-    pollShutdownTimer(0),
+    optionsModel(nullptr),
+    clientModel(nullptr),
+    window(nullptr),
+    pollShutdownTimer(nullptr),
 #ifdef ENABLE_WALLET
-    paymentServer(0),
+    paymentServer(nullptr),
     m_wallet_models(),
 #endif
     returnValue(0),
-    platformStyle(0)
+    platformStyle(nullptr)
 {
     setQuitOnLastWindowClosed(false);
 }
@@ -218,15 +218,15 @@ BitcoinApplication::~BitcoinApplication()
     }
 
     delete window;
-    window = 0;
+    window = nullptr;
 #ifdef ENABLE_WALLET
     delete paymentServer;
-    paymentServer = 0;
+    paymentServer = nullptr;
 #endif
     delete optionsModel;
-    optionsModel = 0;
+    optionsModel = nullptr;
     delete platformStyle;
-    platformStyle = 0;
+    platformStyle = nullptr;
 }
 
 #ifdef ENABLE_WALLET
@@ -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();
@@ -312,7 +312,7 @@ void BitcoinApplication::requestShutdown()
     qDebug() << __func__ << ": Requesting shutdown";
     startThread();
     window->hide();
-    window->setClientModel(0);
+    window->setClientModel(nullptr);
     pollShutdownTimer->stop();
 
 #ifdef ENABLE_WALLET
@@ -323,7 +323,7 @@ void BitcoinApplication::requestShutdown()
     m_wallet_models.clear();
 #endif
     delete clientModel;
-    clientModel = 0;
+    clientModel = nullptr;
 
     m_node.startShutdown();
 
@@ -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

@@ -60,7 +60,7 @@ class AmountSpinBox: public QAbstractSpinBox
         }
     }
 
-    CAmount value(bool *valid_out=0) const
+    CAmount value(bool *valid_out=nullptr) const
     {
         return parse(text(), valid_out);
     }
@@ -159,7 +159,7 @@ class AmountSpinBox: public QAbstractSpinBox
      * return validity.
      * @note Must return 0 if !valid.
      */
-    CAmount parse(const QString &text, bool *valid_out=0) const
+    CAmount parse(const QString &text, bool *valid_out=nullptr) const
     {
         CAmount val = 0;
         bool valid = BitcoinUnits::parse(currentUnit, text, &val);
@@ -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/bitcoinamountfield.h

@@ -26,9 +26,9 @@ class BitcoinAmountField: public QWidget
     Q_PROPERTY(qint64 value READ value WRITE setValue NOTIFY valueChanged USER true)
 
 public:
-    explicit BitcoinAmountField(QWidget *parent = 0);
+    explicit BitcoinAmountField(QWidget *parent = nullptr);
 
-    CAmount value(bool *value=0) const;
+    CAmount value(bool *value=nullptr) const;
     void setValue(const CAmount& value);
 
     /** If allow empty is set to false the field will be set to the minimum allowed value if left empty. **/