qt, refactor: Use default arguments for overridden functions

See Qt docs for QAbstractTableModel and QAbstractItemModel classes.

src/qt/peertablemodel.cpp

@@ -84,7 +84,7 @@ void PeerTableModel::stopAutoRefresh()
     timer->stop();
 }
 
-int PeerTableModel::rowCount(const QModelIndex &parent) const
+int PeerTableModel::rowCount(const QModelIndex& parent) const
 {
     if (parent.isValid()) {
         return 0;
@@ -92,7 +92,7 @@ int PeerTableModel::rowCount(const QModelIndex &parent) const
     return priv->size();
 }
 
-int PeerTableModel::columnCount(const QModelIndex &parent) const
+int PeerTableModel::columnCount(const QModelIndex& parent) const
 {
     if (parent.isValid()) {
         return 0;
@@ -100,7 +100,7 @@ int PeerTableModel::columnCount(const QModelIndex &parent) const
     return columns.length();
 }
 
-QVariant PeerTableModel::data(const QModelIndex &index, int role) const
+QVariant PeerTableModel::data(const QModelIndex& index, int role) const
 {
     if(!index.isValid())
         return QVariant();
@@ -172,7 +172,7 @@ Qt::ItemFlags PeerTableModel::flags(const QModelIndex &index) const
     return retval;
 }
 
-QModelIndex PeerTableModel::index(int row, int column, const QModelIndex &parent) const
+QModelIndex PeerTableModel::index(int row, int column, const QModelIndex& parent) const
 {
     Q_UNUSED(parent);
     CNodeCombinedStats *data = priv->index(row);

src/qt/peertablemodel.h

@@ -61,11 +61,11 @@ public:
 
     /** @name Methods overridden from QAbstractTableModel
         @{*/
-    int rowCount(const QModelIndex &parent) const override;
-    int columnCount(const QModelIndex &parent) const override;
-    QVariant data(const QModelIndex &index, int role) const override;
-    QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
-    QModelIndex index(int row, int column, const QModelIndex &parent) const override;
+    int rowCount(const QModelIndex& parent = QModelIndex()) const override;
+    int columnCount(const QModelIndex& parent = QModelIndex()) const override;
+    QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const override;
+    QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override;
+    QModelIndex index(int row, int column, const QModelIndex& parent = QModelIndex()) const override;
     Qt::ItemFlags flags(const QModelIndex &index) const override;
     /*@}*/