Merge #18914: refactor: Apply override specifier consistently

d044e0ec7d37bbcdf10bbdb903b9119741c7297d refactor: Remove override for final overriders (Hennadii Stepanov)
1551cea2d52cac403ff506a7cc955d8de8fd6f3e refactor: Use override for non-final overriders (Hennadii Stepanov)

Pull request description:

  Two commits are split out from #16710 to make reviewing [easier](https://github.com/bitcoin/bitcoin/pull/16710#issuecomment-625760894).

  From [C++ FAQ](https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines.html#c128-virtual-functions-should-specify-exactly-one-of-virtual-override-or-final):
  > C.128: Virtual functions should specify exactly one of virtual, override, or final
  > **Reason** Readability. Detection of mistakes. Writing explicit `virtual`, `override`, or `final` is self-documenting and enables the compiler to catch mismatch of types and/or names between base and derived classes. However, writing more than one of these three is both redundant and a potential source of errors.

ACKs for top commit:
  practicalswift:
    ACK d044e0ec7d37bbcdf10bbdb903b9119741c7297d: consistent use of `override` prevents bugs + patch looks correct + Travis happy
  MarcoFalke:
    ACK d044e0ec7d37bbcdf10bbdb903b9119741c7297d, based on my understanding that adding `override` or `final` to a function must always be correct, unless it doesn't compile!?
  vasild:
    ACK d044e0ec7

Tree-SHA512: 245fd9b99b8b5cbf8694061f892cb3435f3378c97ebed9f9401ce86d21890211f2234bcc39c9f0f79a4d2806cb31bf8ce41a0f9c2acef4f3a2ac5beca6b077cf

37 files changed, 108 insertions, 107 deletions

diff --git a/src/interfaces/chain.cpp b/src/interfaces/chain.cpp
index 515a2ba1b9..e1a528d99c 100644
--- a/src/interfaces/chain.cpp
+++ b/src/interfaces/chain.cpp
@@ -127,7 +127,7 @@ public:
         ::tableRPC.appendCommand(m_command.name, &m_command);
     }
 
-    void disconnect() override final
+    void disconnect() final
     {
         if (m_wrapped_command) {
             m_wrapped_command = nullptr;
diff --git a/src/qt/addressbookpage.cpp b/src/qt/addressbookpage.cpp
index f48f28d03a..0d3b08fe7d 100644
--- a/src/qt/addressbookpage.cpp
+++ b/src/qt/addressbookpage.cpp
@@ -35,7 +35,7 @@ public:
     }
 
 protected:
-    bool filterAcceptsRow(int row, const QModelIndex& parent) const
+    bool filterAcceptsRow(int row, const QModelIndex& parent) const override
     {
         auto model = sourceModel();
         auto label = model->index(row, AddressTableModel::Label, parent);
diff --git a/src/qt/addressbookpage.h b/src/qt/addressbookpage.h
index 6394d26801..3d303a6f68 100644
--- a/src/qt/addressbookpage.h
+++ b/src/qt/addressbookpage.h
@@ -45,7 +45,7 @@ public:
     const QString &getReturnValue() const { return returnValue; }
 
 public Q_SLOTS:
-    void done(int retval);
+    void done(int retval) override;
 
 private:
     Ui::AddressBookPage *ui;
diff --git a/src/qt/addresstablemodel.h b/src/qt/addresstablemodel.h
index 035f3e0571..97f673caf1 100644
--- a/src/qt/addresstablemodel.h
+++ b/src/qt/addresstablemodel.h
@@ -52,14 +52,14 @@ public:
 
     /** @name Methods overridden from QAbstractTableModel
         @{*/
-    int rowCount(const QModelIndex &parent) const;
-    int columnCount(const QModelIndex &parent) const;
-    QVariant data(const QModelIndex &index, int role) const;
-    bool setData(const QModelIndex &index, const QVariant &value, int role);
-    QVariant headerData(int section, Qt::Orientation orientation, int role) const;
-    QModelIndex index(int row, int column, const QModelIndex &parent) const;
-    bool removeRows(int row, int count, const QModelIndex &parent = QModelIndex());
-    Qt::ItemFlags flags(const QModelIndex &index) const;
+    int rowCount(const QModelIndex &parent) const override;
+    int columnCount(const QModelIndex &parent) const override;
+    QVariant data(const QModelIndex &index, int role) const override;
+    bool setData(const QModelIndex &index, const QVariant &value, int role) override;
+    QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
+    QModelIndex index(int row, int column, const QModelIndex &parent) const override;
+    bool removeRows(int row, int count, const QModelIndex &parent = QModelIndex()) override;
+    Qt::ItemFlags flags(const QModelIndex &index) const override;
     /*@}*/
 
     /* Add an address to the model.
diff --git a/src/qt/askpassphrasedialog.h b/src/qt/askpassphrasedialog.h
index 20fc5045ae..9557e72936 100644
--- a/src/qt/askpassphrasedialog.h
+++ b/src/qt/askpassphrasedialog.h
@@ -32,7 +32,7 @@ public:
     explicit AskPassphraseDialog(Mode mode, QWidget *parent, SecureString* passphrase_out = nullptr);
     ~AskPassphraseDialog();
 
-    void accept();
+    void accept() override;
 
     void setModel(WalletModel *model);
 
@@ -49,8 +49,8 @@ private Q_SLOTS:
     void toggleShowPassword(bool);
 
 protected:
-    bool event(QEvent *event);
-    bool eventFilter(QObject *object, QEvent *event);
+    bool event(QEvent *event) override;
+    bool eventFilter(QObject *object, QEvent *event) override;
 };
 
 #endif // BITCOIN_QT_ASKPASSPHRASEDIALOG_H
diff --git a/src/qt/bantablemodel.h b/src/qt/bantablemodel.h
index 88d5b5811b..57f559fc14 100644
--- a/src/qt/bantablemodel.h
+++ b/src/qt/bantablemodel.h
@@ -56,16 +56,17 @@ public:
 
     /** @name Methods overridden from QAbstractTableModel
         @{*/
-    int rowCount(const QModelIndex &parent) const;
-    int columnCount(const QModelIndex &parent) const;
-    QVariant data(const QModelIndex &index, int role) const;
-    QVariant headerData(int section, Qt::Orientation orientation, int role) const;
-    QModelIndex index(int row, int column, const QModelIndex &parent) const;
-    Qt::ItemFlags flags(const QModelIndex &index) const;
-    void sort(int column, Qt::SortOrder order);
-    bool shouldShow();
+    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;
+    Qt::ItemFlags flags(const QModelIndex &index) const override;
+    void sort(int column, Qt::SortOrder order) override;
     /*@}*/
 
+    bool shouldShow();
+
 public Q_SLOTS:
     void refresh();
 
diff --git a/src/qt/bitcoinaddressvalidator.h b/src/qt/bitcoinaddressvalidator.h
index 30d4a26d0e..52c06828a3 100644
--- a/src/qt/bitcoinaddressvalidator.h
+++ b/src/qt/bitcoinaddressvalidator.h
@@ -17,7 +17,7 @@ class BitcoinAddressEntryValidator : public QValidator
 public:
     explicit BitcoinAddressEntryValidator(QObject *parent);
 
-    State validate(QString &input, int &pos) const;
+    State validate(QString &input, int &pos) const override;
 };
 
 /** Bitcoin address widget validator, checks for a valid bitcoin address.
@@ -29,7 +29,7 @@ class BitcoinAddressCheckValidator : public QValidator
 public:
     explicit BitcoinAddressCheckValidator(QObject *parent);
 
-    State validate(QString &input, int &pos) const;
+    State validate(QString &input, int &pos) const override;
 };
 
 #endif // BITCOIN_QT_BITCOINADDRESSVALIDATOR_H
diff --git a/src/qt/bitcoinamountfield.cpp b/src/qt/bitcoinamountfield.cpp
index 7acc82370f..4c57f1e352 100644
--- a/src/qt/bitcoinamountfield.cpp
+++ b/src/qt/bitcoinamountfield.cpp
@@ -31,7 +31,7 @@ public:
         connect(lineEdit(), &QLineEdit::textEdited, this, &AmountSpinBox::valueChanged);
     }
 
-    QValidator::State validate(QString &text, int &pos) const
+    QValidator::State validate(QString &text, int &pos) const override
     {
         if(text.isEmpty())
             return QValidator::Intermediate;
@@ -41,7 +41,7 @@ public:
         return valid ? QValidator::Intermediate : QValidator::Invalid;
     }
 
-    void fixup(QString &input) const
+    void fixup(QString &input) const override
     {
         bool valid;
         CAmount val;
@@ -87,7 +87,7 @@ public:
         m_max_amount = value;
     }
 
-    void stepBy(int steps)
+    void stepBy(int steps) override
     {
         bool valid = false;
         CAmount val = value(&valid);
@@ -114,7 +114,7 @@ public:
         singleStep = step;
     }
 
-    QSize minimumSizeHint() const
+    QSize minimumSizeHint() const override
     {
         if(cachedMinimumSizeHint.isEmpty())
         {
@@ -175,7 +175,7 @@ private:
     }
 
 protected:
-    bool event(QEvent *event)
+    bool event(QEvent *event) override
     {
         if (event->type() == QEvent::KeyPress || event->type() == QEvent::KeyRelease)
         {
@@ -190,7 +190,7 @@ protected:
         return QAbstractSpinBox::event(event);
     }
 
-    StepEnabled stepEnabled() const
+    StepEnabled stepEnabled() const override
     {
         if (isReadOnly()) // Disable steps when AmountSpinBox is read-only
             return StepNone;
diff --git a/src/qt/bitcoinamountfield.h b/src/qt/bitcoinamountfield.h
index 2db6b65f2c..d3e61aac29 100644
--- a/src/qt/bitcoinamountfield.h
+++ b/src/qt/bitcoinamountfield.h
@@ -70,7 +70,7 @@ Q_SIGNALS:
 
 protected:
     /** Intercept focus-in event and ',' key presses */
-    bool eventFilter(QObject *object, QEvent *event);
+    bool eventFilter(QObject *object, QEvent *event) override;
 
 private:
     AmountSpinBox *amount;
diff --git a/src/qt/bitcoingui.h b/src/qt/bitcoingui.h
index dda88930db..6733585f68 100644
--- a/src/qt/bitcoingui.h
+++ b/src/qt/bitcoingui.h
@@ -99,12 +99,12 @@ public:
     void unsubscribeFromCoreSignals();
 
 protected:
-    void changeEvent(QEvent *e);
-    void closeEvent(QCloseEvent *event);
-    void showEvent(QShowEvent *event);
-    void dragEnterEvent(QDragEnterEvent *event);
-    void dropEvent(QDropEvent *event);
-    bool eventFilter(QObject *object, QEvent *event);
+    void changeEvent(QEvent *e) override;
+    void closeEvent(QCloseEvent *event) override;
+    void showEvent(QShowEvent *event) override;
+    void dragEnterEvent(QDragEnterEvent *event) override;
+    void dropEvent(QDropEvent *event) override;
+    bool eventFilter(QObject *object, QEvent *event) override;
 
 private:
     interfaces::Node& m_node;
@@ -325,7 +325,7 @@ public:
 
 protected:
     /** So that it responds to left-button clicks */
-    void mousePressEvent(QMouseEvent *event);
+    void mousePressEvent(QMouseEvent *event) override;
 
 private:
     OptionsModel *optionsModel;
diff --git a/src/qt/bitcoinunits.h b/src/qt/bitcoinunits.h
index 4c8a889965..1ff4702117 100644
--- a/src/qt/bitcoinunits.h
+++ b/src/qt/bitcoinunits.h
@@ -90,8 +90,8 @@ public:
         /** Unit identifier */
         UnitRole = Qt::UserRole
     };
-    int rowCount(const QModelIndex &parent) const;
-    QVariant data(const QModelIndex &index, int role) const;
+    int rowCount(const QModelIndex &parent) const override;
+    QVariant data(const QModelIndex &index, int role) const override;
     ///@}
 
     static QString removeSpaces(QString text)
diff --git a/src/qt/coincontroldialog.h b/src/qt/coincontroldialog.h
index efc06a7656..eebab34a9d 100644
--- a/src/qt/coincontroldialog.h
+++ b/src/qt/coincontroldialog.h
@@ -34,7 +34,7 @@ public:
     explicit CCoinControlWidgetItem(int type = Type) : QTreeWidgetItem(type) {}
     explicit CCoinControlWidgetItem(QTreeWidgetItem *parent, int type = Type) : QTreeWidgetItem(parent, type) {}
 
-    bool operator<(const QTreeWidgetItem &other) const;
+    bool operator<(const QTreeWidgetItem &other) const override;
 };
 
 
diff --git a/src/qt/coincontroltreewidget.h b/src/qt/coincontroltreewidget.h
index 86af555385..ac03a409c1 100644
--- a/src/qt/coincontroltreewidget.h
+++ b/src/qt/coincontroltreewidget.h
@@ -16,7 +16,7 @@ public:
     explicit CoinControlTreeWidget(QWidget *parent = nullptr);
 
 protected:
-    virtual void keyPressEvent(QKeyEvent *event);
+    virtual void keyPressEvent(QKeyEvent *event) override;
 };
 
 #endif // BITCOIN_QT_COINCONTROLTREEWIDGET_H
diff --git a/src/qt/editaddressdialog.h b/src/qt/editaddressdialog.h
index 4d0e0709be..3be63156fd 100644
--- a/src/qt/editaddressdialog.h
+++ b/src/qt/editaddressdialog.h
@@ -40,7 +40,7 @@ public:
     void setAddress(const QString &address);
 
 public Q_SLOTS:
-    void accept();
+    void accept() override;
 
 private:
     bool saveCurrentRow();
diff --git a/src/qt/guiutil.h b/src/qt/guiutil.h
index 0d9293fbad..8b9fca4fb1 100644
--- a/src/qt/guiutil.h
+++ b/src/qt/guiutil.h
@@ -145,7 +145,7 @@ namespace GUIUtil
         explicit ToolTipToRichTextFilter(int size_threshold, QObject *parent = nullptr);
 
     protected:
-        bool eventFilter(QObject *obj, QEvent *evt);
+        bool eventFilter(QObject *obj, QEvent *evt) override;
 
     private:
         int size_threshold;
@@ -227,7 +227,7 @@ namespace GUIUtil
          */
         void clicked(const QPoint& point);
     protected:
-        void mouseReleaseEvent(QMouseEvent *event);
+        void mouseReleaseEvent(QMouseEvent *event) override;
     };
 
     class ClickableProgressBar : public QProgressBar
@@ -240,7 +240,7 @@ namespace GUIUtil
          */
         void clicked(const QPoint& point);
     protected:
-        void mouseReleaseEvent(QMouseEvent *event);
+        void mouseReleaseEvent(QMouseEvent *event) override;
     };
 
     typedef ClickableProgressBar ProgressBar;
@@ -255,7 +255,7 @@ namespace GUIUtil
         void keyEscapePressed();
 
     private:
-        bool eventFilter(QObject *object, QEvent *event);
+        bool eventFilter(QObject *object, QEvent *event) override;
     };
 
     // Fix known bugs in QProgressDialog class.
diff --git a/src/qt/modaloverlay.h b/src/qt/modaloverlay.h
index 076ec30b58..a565d7d8f3 100644
--- a/src/qt/modaloverlay.h
+++ b/src/qt/modaloverlay.h
@@ -35,8 +35,8 @@ public Q_SLOTS:
     bool isLayerVisible() const { return layerIsVisible; }
 
 protected:
-    bool eventFilter(QObject * obj, QEvent * ev);
-    bool event(QEvent* ev);
+    bool eventFilter(QObject * obj, QEvent * ev) override;
+    bool event(QEvent* ev) override;
 
 private:
     Ui::ModalOverlay *ui;
diff --git a/src/qt/openuridialog.h b/src/qt/openuridialog.h
index 4b610f74d7..667af2ec75 100644
--- a/src/qt/openuridialog.h
+++ b/src/qt/openuridialog.h
@@ -22,7 +22,7 @@ public:
     QString getURI();
 
 protected Q_SLOTS:
-    void accept();
+    void accept() override;
 
 private:
     Ui::OpenURIDialog *ui;
diff --git a/src/qt/optionsdialog.h b/src/qt/optionsdialog.h
index 9bc1c8ae4f..568c8b6fd0 100644
--- a/src/qt/optionsdialog.h
+++ b/src/qt/optionsdialog.h
@@ -28,7 +28,7 @@ class ProxyAddressValidator : public QValidator
 public:
     explicit ProxyAddressValidator(QObject *parent);
 
-    State validate(QString &input, int &pos) const;
+    State validate(QString &input, int &pos) const override;
 };
 
 /** Preferences dialog. */
diff --git a/src/qt/optionsmodel.h b/src/qt/optionsmodel.h
index b3260349e7..6ca5ac9d75 100644
--- a/src/qt/optionsmodel.h
+++ b/src/qt/optionsmodel.h
@@ -68,9 +68,9 @@ public:
     void Init(bool resetSettings = false);
     void Reset();
 
-    int rowCount(const QModelIndex & parent = QModelIndex()) const;
-    QVariant data(const QModelIndex & index, int role = Qt::DisplayRole) const;
-    bool setData(const QModelIndex & index, const QVariant & value, int role = Qt::EditRole);
+    int rowCount(const QModelIndex & parent = QModelIndex()) const override;
+    QVariant data(const QModelIndex & index, int role = Qt::DisplayRole) const override;
+    bool setData(const QModelIndex & index, const QVariant & value, int role = Qt::EditRole) override;
     /** Updates current unit in memory, settings and emits displayUnitChanged(newUnit) signal */
     void setDisplayUnit(const QVariant &value);
 
diff --git a/src/qt/overviewpage.cpp b/src/qt/overviewpage.cpp
index e0ae1f9e92..e20ec229fc 100644
--- a/src/qt/overviewpage.cpp
+++ b/src/qt/overviewpage.cpp
@@ -35,7 +35,7 @@ public:
     }
 
     inline void paint(QPainter *painter, const QStyleOptionViewItem &option,
-                      const QModelIndex &index ) const
+                      const QModelIndex &index ) const override
     {
         painter->save();
 
@@ -99,7 +99,7 @@ public:
         painter->restore();
     }
 
-    inline QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const
+    inline QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const override
     {
         return QSize(DECORATION_SIZE, DECORATION_SIZE);
     }
diff --git a/src/qt/paymentserver.h b/src/qt/paymentserver.h
index aa9a7327ba..154f4a7ea6 100644
--- a/src/qt/paymentserver.h
+++ b/src/qt/paymentserver.h
@@ -98,7 +98,7 @@ private Q_SLOTS:
 protected:
     // Constructor registers this on the parent QApplication to
     // receive QEvent::FileOpen and QEvent:Drop events
-    bool eventFilter(QObject *object, QEvent *event);
+    bool eventFilter(QObject *object, QEvent *event) override;
 
 private:
     bool saveURIs;                      // true during startup
diff --git a/src/qt/peertablemodel.h b/src/qt/peertablemodel.h
index 0e20b1d9dc..99de772ac0 100644
--- a/src/qt/peertablemodel.h
+++ b/src/qt/peertablemodel.h
@@ -68,13 +68,13 @@ public:
 
     /** @name Methods overridden from QAbstractTableModel
         @{*/
-    int rowCount(const QModelIndex &parent) const;
-    int columnCount(const QModelIndex &parent) const;
-    QVariant data(const QModelIndex &index, int role) const;
-    QVariant headerData(int section, Qt::Orientation orientation, int role) const;
-    QModelIndex index(int row, int column, const QModelIndex &parent) const;
-    Qt::ItemFlags flags(const QModelIndex &index) const;
-    void sort(int column, Qt::SortOrder order);
+    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;
+    Qt::ItemFlags flags(const QModelIndex &index) const override;
+    void sort(int column, Qt::SortOrder order) override;
     /*@}*/
 
 public Q_SLOTS:
diff --git a/src/qt/qrimagewidget.h b/src/qt/qrimagewidget.h
index 345bb64092..cca598c2ce 100644
--- a/src/qt/qrimagewidget.h
+++ b/src/qt/qrimagewidget.h
@@ -35,8 +35,8 @@ public Q_SLOTS:
     void copyImage();
 
 protected:
-    virtual void mousePressEvent(QMouseEvent *event);
-    virtual void contextMenuEvent(QContextMenuEvent *event);
+    virtual void mousePressEvent(QMouseEvent *event) override;
+    virtual void contextMenuEvent(QContextMenuEvent *event) override;
 
 private:
     QMenu *contextMenu;
diff --git a/src/qt/qvalidatedlineedit.h b/src/qt/qvalidatedlineedit.h
index 815d5e0040..2c72b2ecda 100644
--- a/src/qt/qvalidatedlineedit.h
+++ b/src/qt/qvalidatedlineedit.h
@@ -21,8 +21,8 @@ public:
     bool isValid();
 
 protected:
-    void focusInEvent(QFocusEvent *evt);
-    void focusOutEvent(QFocusEvent *evt);
+    void focusInEvent(QFocusEvent *evt) override;
+    void focusOutEvent(QFocusEvent *evt) override;
 
 private:
     bool valid;
diff --git a/src/qt/receivecoinsdialog.h b/src/qt/receivecoinsdialog.h
index 5bca2f46e2..2f48cd58f0 100644
--- a/src/qt/receivecoinsdialog.h
+++ b/src/qt/receivecoinsdialog.h
@@ -46,11 +46,11 @@ public:
 
 public Q_SLOTS:
     void clear();
-    void reject();
-    void accept();
+    void reject() override;
+    void accept() override;
 
 protected:
-    virtual void keyPressEvent(QKeyEvent *event);
+    virtual void keyPressEvent(QKeyEvent *event) override;
 
 private:
     Ui::ReceiveCoinsDialog *ui;
@@ -61,7 +61,7 @@ private:
 
     QModelIndex selectedRow();
     void copyColumnToClipboard(int column);
-    virtual void resizeEvent(QResizeEvent *event);
+    virtual void resizeEvent(QResizeEvent *event) override;
 
 private Q_SLOTS:
     void on_receiveButton_clicked();
diff --git a/src/qt/recentrequeststablemodel.h b/src/qt/recentrequeststablemodel.h
index 5e7f6acdc8..addf5ad0ae 100644
--- a/src/qt/recentrequeststablemodel.h
+++ b/src/qt/recentrequeststablemodel.h
@@ -73,14 +73,15 @@ public:
 
     /** @name Methods overridden from QAbstractTableModel
         @{*/
-    int rowCount(const QModelIndex &parent) const;
-    int columnCount(const QModelIndex &parent) const;
-    QVariant data(const QModelIndex &index, int role) const;
-    bool setData(const QModelIndex &index, const QVariant &value, int role);
-    QVariant headerData(int section, Qt::Orientation orientation, int role) const;
-    QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const;
-    bool removeRows(int row, int count, const QModelIndex &parent = QModelIndex());
-    Qt::ItemFlags flags(const QModelIndex &index) const;
+    int rowCount(const QModelIndex &parent) const override;
+    int columnCount(const QModelIndex &parent) const override;
+    QVariant data(const QModelIndex &index, int role) const override;
+    bool setData(const QModelIndex &index, const QVariant &value, int role) override;
+    QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
+    QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const override;
+    bool removeRows(int row, int count, const QModelIndex &parent = QModelIndex()) override;
+    Qt::ItemFlags flags(const QModelIndex &index) const override;
+    void sort(int column, Qt::SortOrder order = Qt::AscendingOrder) override;
     /*@}*/
 
     const RecentRequestEntry &entry(int row) const { return list[row]; }
@@ -89,7 +90,6 @@ public:
     void addNewRequest(RecentRequestEntry &recipient);
 
 public Q_SLOTS:
-    void sort(int column, Qt::SortOrder order = Qt::AscendingOrder);
     void updateDisplayUnit();
 
 private:
diff --git a/src/qt/rpcconsole.cpp b/src/qt/rpcconsole.cpp
index bfe316bdcd..b7fbca50ac 100644
--- a/src/qt/rpcconsole.cpp
+++ b/src/qt/rpcconsole.cpp
@@ -115,8 +115,8 @@ class QtRPCTimerInterface: public RPCTimerInterface
 {
 public:
     ~QtRPCTimerInterface() {}
-    const char *Name() { return "Qt"; }
-    RPCTimerBase* NewTimer(std::function<void()>& func, int64_t millis)
+    const char *Name() override { return "Qt"; }
+    RPCTimerBase* NewTimer(std::function<void()>& func, int64_t millis) override
     {
         return new QtRPCTimerBase(func, millis);
     }
diff --git a/src/qt/rpcconsole.h b/src/qt/rpcconsole.h
index f586d04022..de8e37cca2 100644
--- a/src/qt/rpcconsole.h
+++ b/src/qt/rpcconsole.h
@@ -71,8 +71,8 @@ public:
     QKeySequence tabShortcut(TabTypes tab_type) const;
 
 protected:
-    virtual bool eventFilter(QObject* obj, QEvent *event);
-    void keyPressEvent(QKeyEvent *);
+    virtual bool eventFilter(QObject* obj, QEvent *event) override;
+    void keyPressEvent(QKeyEvent *) override;
 
 private Q_SLOTS:
     void on_lineEdit_returnPressed();
@@ -83,9 +83,9 @@ private Q_SLOTS:
     void on_sldGraphRange_valueChanged(int value);
     /** update traffic statistics */
     void updateTrafficStats(quint64 totalBytesIn, quint64 totalBytesOut);
-    void resizeEvent(QResizeEvent *event);
-    void showEvent(QShowEvent *event);
-    void hideEvent(QHideEvent *event);
+    void resizeEvent(QResizeEvent *event) override;
+    void showEvent(QShowEvent *event) override;
+    void hideEvent(QHideEvent *event) override;
     /** Show custom context menu on Peers tab */
     void showPeersTableContextMenu(const QPoint& point);
     /** Show custom context menu on Bans tab */
diff --git a/src/qt/sendcoinsdialog.h b/src/qt/sendcoinsdialog.h
index 36bc2a846b..b2dc15181d 100644
--- a/src/qt/sendcoinsdialog.h
+++ b/src/qt/sendcoinsdialog.h
@@ -47,8 +47,8 @@ public:
 
 public Q_SLOTS:
     void clear();
-    void reject();
-    void accept();
+    void reject() override;
+    void accept() override;
     SendCoinsEntry *addEntry();
     void updateTabsAndLabels();
     void setBalance(const interfaces::WalletBalances& balances);
@@ -112,7 +112,7 @@ class SendConfirmationDialog : public QMessageBox
 
 public:
     SendConfirmationDialog(const QString& title, const QString& text, const QString& informative_text = "", const QString& detailed_text = "", int secDelay = SEND_CONFIRM_DELAY, const QString& confirmText = "Send", QWidget* parent = nullptr);
-    int exec();
+    int exec() override;
 
 private Q_SLOTS:
     void countDown();
diff --git a/src/qt/signverifymessagedialog.h b/src/qt/signverifymessagedialog.h
index d2e04cd4fe..d33a2d038d 100644
--- a/src/qt/signverifymessagedialog.h
+++ b/src/qt/signverifymessagedialog.h
@@ -30,7 +30,7 @@ public:
     void showTab_VM(bool fShow);
 
 protected:
-    bool eventFilter(QObject *object, QEvent *event);
+    bool eventFilter(QObject *object, QEvent *event) override;
 
 private:
     Ui::SignVerifyMessageDialog *ui;
diff --git a/src/qt/splashscreen.h b/src/qt/splashscreen.h
index f99dd0c701..3158524117 100644
--- a/src/qt/splashscreen.h
+++ b/src/qt/splashscreen.h
@@ -32,8 +32,8 @@ public:
     ~SplashScreen();
 
 protected:
-    void paintEvent(QPaintEvent *event);
-    void closeEvent(QCloseEvent *event);
+    void paintEvent(QPaintEvent *event) override;
+    void closeEvent(QCloseEvent *event) override;
 
 public Q_SLOTS:
     /** Hide the splash screen window and schedule the splash screen object for deletion */
@@ -43,7 +43,7 @@ public Q_SLOTS:
     void showMessage(const QString &message, int alignment, const QColor &color);
 
 protected:
-    bool eventFilter(QObject * obj, QEvent * ev);
+    bool eventFilter(QObject * obj, QEvent * ev) override;
 
 private:
     /** Connect core signals to splash screen */
diff --git a/src/qt/trafficgraphwidget.h b/src/qt/trafficgraphwidget.h
index 7e8bfb2337..2d8c825815 100644
--- a/src/qt/trafficgraphwidget.h
+++ b/src/qt/trafficgraphwidget.h
@@ -25,7 +25,7 @@ public:
     int getGraphRangeMins() const;
 
 protected:
-    void paintEvent(QPaintEvent *);
+    void paintEvent(QPaintEvent *) override;
 
 public Q_SLOTS:
     void updateRates();
diff --git a/src/qt/transactionfilterproxy.h b/src/qt/transactionfilterproxy.h
index 685f8d3a26..d6bb84f7e6 100644
--- a/src/qt/transactionfilterproxy.h
+++ b/src/qt/transactionfilterproxy.h
@@ -49,10 +49,10 @@ public:
     /** Set whether to show conflicted transactions. */
     void setShowInactive(bool showInactive);
 
-    int rowCount(const QModelIndex &parent = QModelIndex()) const;
+    int rowCount(const QModelIndex &parent = QModelIndex()) const override;
 
 protected:
-    bool filterAcceptsRow(int source_row, const QModelIndex & source_parent) const;
+    bool filterAcceptsRow(int source_row, const QModelIndex & source_parent) const override;
 
 private:
     QDateTime dateFrom;
diff --git a/src/qt/transactiontablemodel.h b/src/qt/transactiontablemodel.h
index 7a7d98962b..f06f0ea15f 100644
--- a/src/qt/transactiontablemodel.h
+++ b/src/qt/transactiontablemodel.h
@@ -76,11 +76,11 @@ public:
         RawDecorationRole,
     };
 
-    int rowCount(const QModelIndex &parent) const;
-    int columnCount(const QModelIndex &parent) const;
-    QVariant data(const QModelIndex &index, int role) const;
-    QVariant headerData(int section, Qt::Orientation orientation, int role) const;
-    QModelIndex index(int row, int column, const QModelIndex & parent = QModelIndex()) const;
+    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 = QModelIndex()) const override;
     bool processingQueuedTransactions() const { return fProcessingQueuedTransactions; }
 
 private:
diff --git a/src/qt/transactionview.h b/src/qt/transactionview.h
index eca5656077..268e3751b3 100644
--- a/src/qt/transactionview.h
+++ b/src/qt/transactionview.h
@@ -82,9 +82,9 @@ private:
 
     GUIUtil::TableViewLastColumnResizingFixer *columnResizingFixer;
 
-    virtual void resizeEvent(QResizeEvent* event);
+    virtual void resizeEvent(QResizeEvent* event) override;
 
-    bool eventFilter(QObject *obj, QEvent *event);
+    bool eventFilter(QObject *obj, QEvent *event) override;
 
 private Q_SLOTS:
     void contextualMenu(const QPoint &);
diff --git a/src/qt/utilitydialog.h b/src/qt/utilitydialog.h
index b6a42d3d9d..425b468f40 100644
--- a/src/qt/utilitydialog.h
+++ b/src/qt/utilitydialog.h
@@ -51,7 +51,7 @@ public:
     static QWidget* showShutdownWindow(QMainWindow* window);
 
 protected:
-    void closeEvent(QCloseEvent *event);
+    void closeEvent(QCloseEvent *event) override;
 };
 
 #endif // BITCOIN_QT_UTILITYDIALOG_H
diff --git a/src/script/descriptor.cpp b/src/script/descriptor.cpp
index 5279f40506..ed0175bb10 100644
--- a/src/script/descriptor.cpp
+++ b/src/script/descriptor.cpp
@@ -481,7 +481,7 @@ public:
         return AddChecksum(ret);
     }
 
-    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override final
+    bool ToPrivateString(const SigningProvider& arg, std::string& out) const final
     {
         bool ret = ToStringHelper(&arg, out, true);
         out = AddChecksum(out);