QtHelp: Bit more cleanup in cpp files

Inline some short methods in private API.
Use more {} for default constructed values.
Fix indentations.
Add some TODOs.

Task-number: QTBUG-122025
Change-Id: I29062709f6d302a8768ead1c20eda3af5c256c74
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

27 files changed, 249 insertions, 450 deletions

diff --git a/src/assistant/help/qcompressedhelpinfo.cpp b/src/assistant/help/qcompressedhelpinfo.cpp
index b88a6faf2..5841424b8 100644
--- a/src/assistant/help/qcompressedhelpinfo.cpp
+++ b/src/assistant/help/qcompressedhelpinfo.cpp
@@ -21,7 +21,6 @@ public:
         , m_version(other.m_version)
         , m_isNull(other.m_isNull)
     { }
-    ~QCompressedHelpInfoPrivate() = default;
 
     QString m_namespaceName;
     QString m_component;
@@ -54,8 +53,7 @@ public:
 */
 QCompressedHelpInfo::QCompressedHelpInfo()
     : d(new QCompressedHelpInfoPrivate)
-{
-}
+{}
 
 /*!
     Constructs a copy of \a other.
@@ -133,7 +131,7 @@ QCompressedHelpInfo QCompressedHelpInfo::fromCompressedHelpFile(const QString &d
 {
     QHelpDBReader reader(documentationFileName,
         QHelpGlobal::uniquifyConnectionName(QLatin1String("GetCompressedHelpInfo"),
-        QThread::currentThread()), nullptr);
+            QThread::currentThread()), nullptr); // TODO: Replace QThread with *this
     if (reader.init()) {
         QCompressedHelpInfo info;
         info.d->m_namespaceName = reader.namespaceName();
@@ -142,7 +140,7 @@ QCompressedHelpInfo QCompressedHelpInfo::fromCompressedHelpFile(const QString &d
         info.d->m_isNull = false;
         return info;
     }
-    return QCompressedHelpInfo();
+    return {};
 }
 
 QT_END_NAMESPACE
diff --git a/src/assistant/help/qfilternamedialog.cpp b/src/assistant/help/qfilternamedialog.cpp
index 7b060e5b4..63232fc45 100644
--- a/src/assistant/help/qfilternamedialog.cpp
+++ b/src/assistant/help/qfilternamedialog.cpp
@@ -15,8 +15,7 @@ QFilterNameDialog::QFilterNameDialog(QWidget *parent)
             this, &QDialog::accept);
     connect(m_ui.buttonBox->button(QDialogButtonBox::Cancel), &QAbstractButton::clicked,
             this, &QDialog::reject);
-    connect(m_ui.lineEdit, &QLineEdit::textChanged,
-            this, &QFilterNameDialog::updateOkButton);
+    connect(m_ui.lineEdit, &QLineEdit::textChanged, this, &QFilterNameDialog::updateOkButton);
     m_ui.buttonBox->button(QDialogButtonBox::Ok)->setDisabled(true);
 }
 
@@ -26,15 +25,9 @@ void QFilterNameDialog::setFilterName(const QString &filter)
     m_ui.lineEdit->selectAll();
 }
 
-QString QFilterNameDialog::filterName() const
-{
-    return m_ui.lineEdit->text();
-}
-
 void QFilterNameDialog::updateOkButton()
 {
-    m_ui.buttonBox->button(QDialogButtonBox::Ok)
-        ->setDisabled(m_ui.lineEdit->text().isEmpty());
+    m_ui.buttonBox->button(QDialogButtonBox::Ok)->setDisabled(m_ui.lineEdit->text().isEmpty());
 }
 
 QT_END_NAMESPACE
diff --git a/src/assistant/help/qfilternamedialog_p.h b/src/assistant/help/qfilternamedialog_p.h
index 024bd4c21..3fd9ba304 100644
--- a/src/assistant/help/qfilternamedialog_p.h
+++ b/src/assistant/help/qfilternamedialog_p.h
@@ -29,7 +29,7 @@ public:
     QFilterNameDialog(QWidget *parent = nullptr);
 
     void setFilterName(const QString &filter);
-    QString filterName() const;
+    QString filterName() const { return m_ui.lineEdit->text(); }
 
 private slots:
     void updateOkButton();
diff --git a/src/assistant/help/qhelp_global.cpp b/src/assistant/help/qhelp_global.cpp
index f4b8ac01c..3eb964766 100644
--- a/src/assistant/help/qhelp_global.cpp
+++ b/src/assistant/help/qhelp_global.cpp
@@ -6,18 +6,14 @@
 #include <QtCore/qcoreapplication.h>
 #include <QtCore/qhash.h>
 #include <QtCore/qmutex.h>
-#include <QtCore/qregularexpression.h>
 #include <QtGui/qtextdocument.h>
 
 QString QHelpGlobal::uniquifyConnectionName(const QString &name, void *pointer)
 {
     static QMutex mutex;
     QMutexLocker locker(&mutex);
-
-    static QHash<QString,quint16> idHash;
-
-    return QString::fromLatin1("%1-%2-%3").
-        arg(name).arg(quintptr(pointer)).arg(++idHash[name]);
+    static QHash<QString, quint16> idHash;
+    return QString::asprintf("%ls-%p-%d", qUtf16Printable(name), pointer, ++idHash[name]);
 }
 
 QString QHelpGlobal::documentTitle(const QString &content)
diff --git a/src/assistant/help/qhelp_global.h b/src/assistant/help/qhelp_global.h
index 64c158e78..b7367ee37 100644
--- a/src/assistant/help/qhelp_global.h
+++ b/src/assistant/help/qhelp_global.h
@@ -18,7 +18,10 @@ class QString;
 #   define QHELP_EXPORT Q_DECL_IMPORT
 #endif
 
-class QHELP_EXPORT QHelpGlobal {
+// TODO Qt 7.0: Remove the class and make it a namespace with a collection of functions.
+//              Review, if they are still need to be public.
+class QHELP_EXPORT QHelpGlobal
+{
 public:
     static QString uniquifyConnectionName(const QString &name, void *pointer);
     static QString documentTitle(const QString &content);
diff --git a/src/assistant/help/qhelpcollectionhandler.cpp b/src/assistant/help/qhelpcollectionhandler.cpp
index 4d0d5d679..5f0649edc 100644
--- a/src/assistant/help/qhelpcollectionhandler.cpp
+++ b/src/assistant/help/qhelpcollectionhandler.cpp
@@ -74,8 +74,7 @@ bool QHelpCollectionHandler::isDBOpened() const
     if (m_query)
         return true;
     auto *that = const_cast<QHelpCollectionHandler *>(this);
-    emit that->error(tr("The collection file \"%1\" is not set up yet.").
-                     arg(m_collectionFile));
+    emit that->error(tr("The collection file \"%1\" is not set up yet.").arg(m_collectionFile));
     return false;
 }
 
@@ -87,12 +86,7 @@ void QHelpCollectionHandler::closeDB()
     delete m_query;
     m_query = nullptr;
     QSqlDatabase::removeDatabase(m_connectionName);
-    m_connectionName = QString();
-}
-
-QString QHelpCollectionHandler::collectionFile() const
-{
-    return m_collectionFile;
+    m_connectionName.clear();
 }
 
 bool QHelpCollectionHandler::openCollectionFile()
@@ -229,7 +223,6 @@ bool QHelpCollectionHandler::openCollectionFile()
             unregisterDocumentation(info.namespaceName);
         }
     }
-
     return true;
 }
 
@@ -238,8 +231,7 @@ QString QHelpCollectionHandler::absoluteDocPath(const QString &fileName) const
     const QFileInfo fi(collectionFile());
     return QDir::isAbsolutePath(fileName)
             ? fileName
-            : QFileInfo(fi.absolutePath() + QLatin1Char('/') + fileName)
-              .absoluteFilePath();
+            : QFileInfo(fi.absolutePath() + QLatin1Char('/') + fileName).absoluteFilePath();
 }
 
 bool QHelpCollectionHandler::isTimeStampCorrect(const TimeStamp &timeStamp) const
@@ -256,8 +248,8 @@ bool QHelpCollectionHandler::isTimeStampCorrect(const TimeStamp &timeStamp) cons
         return false;
 
     m_query->prepare(QLatin1String("SELECT FilePath "
-                                  "FROM NamespaceTable "
-                                  "WHERE Id = ?"));
+                                   "FROM NamespaceTable "
+                                   "WHERE Id = ?"));
     m_query->bindValue(0, timeStamp.namespaceId);
     if (!m_query->exec() || !m_query->next())
         return false;
@@ -273,12 +265,12 @@ bool QHelpCollectionHandler::isTimeStampCorrect(const TimeStamp &timeStamp) cons
 bool QHelpCollectionHandler::hasTimeStampInfo(const QString &nameSpace) const
 {
     m_query->prepare(QLatin1String("SELECT "
-                                      "TimeStampTable.NamespaceId "
-                                  "FROM "
-                                      "NamespaceTable, "
-                                      "TimeStampTable "
-                                  "WHERE NamespaceTable.Id = TimeStampTable.NamespaceId "
-                                  "AND NamespaceTable.Name = ? LIMIT 1"));
+                                       "TimeStampTable.NamespaceId "
+                                   "FROM "
+                                       "NamespaceTable, "
+                                       "TimeStampTable "
+                                   "WHERE NamespaceTable.Id = TimeStampTable.NamespaceId "
+                                   "AND NamespaceTable.Name = ? LIMIT 1"));
     m_query->bindValue(0, nameSpace);
     if (!m_query->exec())
         return false;
@@ -315,8 +307,7 @@ bool QHelpCollectionHandler::copyCollectionFile(const QString &fileName)
 
     const QFileInfo fi(fileName);
     if (fi.exists()) {
-        emit error(tr("The collection file \"%1\" already exists.").
-                   arg(fileName));
+        emit error(tr("The collection file \"%1\" already exists.").arg(fileName));
         return false;
     }
 
@@ -537,7 +528,6 @@ QStringList QHelpCollectionHandler::customFilters() const
     return list;
 }
 
-
 QStringList QHelpCollectionHandler::filters() const
 {
     QStringList list;
@@ -999,7 +989,7 @@ bool QHelpCollectionHandler::fileExists(const QUrl &url) const
 static QString prepareFilterQuery(const QString &filterName)
 {
     if (filterName.isEmpty())
-        return QString();
+        return {};
 
     return QString::fromLatin1(" AND EXISTS(SELECT * FROM Filter WHERE Filter.Name = ?) "
                                "AND ("
@@ -1066,7 +1056,7 @@ static QString prepareFilterQuery(int attributesCount,
                                   const QString &filterColumnName)
 {
     if (!attributesCount)
-        return QString();
+        return {};
 
     QString filterQuery = QString::fromLatin1(" AND (%1.%2 IN (").arg(idTableName, idColumnName);
 
@@ -1116,11 +1106,11 @@ QString QHelpCollectionHandler::namespaceForFile(const QUrl &url,
                                                  const QStringList &filterAttributes) const
 {
     if (!isDBOpened())
-        return QString();
+        return {};
 
     const FileInfo fileInfo = extractFileInfo(url);
     if (fileInfo.namespaceName.isEmpty())
-        return QString();
+        return {};
 
     const QString filterlessQuery = QLatin1String(
                 "SELECT DISTINCT "
@@ -1147,14 +1137,14 @@ QString QHelpCollectionHandler::namespaceForFile(const QUrl &url,
     bindFilterQuery(m_query, 2, filterAttributes);
 
     if (!m_query->exec())
-        return QString();
+        return {};
 
-    QList<QString> namespaceList;
+    QStringList namespaceList;
     while (m_query->next())
         namespaceList.append(m_query->value(0).toString());
 
     if (namespaceList.isEmpty())
-        return QString();
+        return {};
 
     if (namespaceList.contains(fileInfo.namespaceName))
         return fileInfo.namespaceName;
@@ -1175,11 +1165,11 @@ QString QHelpCollectionHandler::namespaceForFile(const QUrl &url,
                                                  const QString &filterName) const
 {
     if (!isDBOpened())
-        return QString();
+        return {};
 
     const FileInfo fileInfo = extractFileInfo(url);
     if (fileInfo.namespaceName.isEmpty())
-        return QString();
+        return {};
 
     const QString filterlessQuery = QLatin1String(
                 "SELECT DISTINCT "
@@ -1202,14 +1192,14 @@ QString QHelpCollectionHandler::namespaceForFile(const QUrl &url,
     bindFilterQuery(m_query, 2, filterName);
 
     if (!m_query->exec())
-        return QString();
+        return {};
 
-    QList<QString> namespaceList;
+    QStringList namespaceList;
     while (m_query->next())
         namespaceList.append(m_query->value(0).toString());
 
     if (namespaceList.isEmpty())
-        return QString();
+        return {};
 
     if (namespaceList.contains(fileInfo.namespaceName))
         return fileInfo.namespaceName;
@@ -1231,7 +1221,7 @@ QStringList QHelpCollectionHandler::files(const QString &namespaceName,
                                           const QString &extensionFilter) const
 {
     if (!isDBOpened())
-        return QStringList();
+        return {};
 
     const QString extensionQuery = extensionFilter.isEmpty()
             ? QString() : QLatin1String(" AND FileNameTable.Name LIKE ?");
@@ -1264,7 +1254,7 @@ QStringList QHelpCollectionHandler::files(const QString &namespaceName,
     bindFilterQuery(m_query, bindCount, filterAttributes);
 
     if (!m_query->exec())
-        return QStringList();
+        return {};
 
     QStringList fileNames;
     while (m_query->next()) {
@@ -1281,7 +1271,7 @@ QStringList QHelpCollectionHandler::files(const QString &namespaceName,
                                           const QString &extensionFilter) const
 {
     if (!isDBOpened())
-        return QStringList();
+        return {};
 
     const QString extensionQuery = extensionFilter.isEmpty()
             ? QString() : QLatin1String(" AND FileNameTable.Name LIKE ?");
@@ -1311,7 +1301,7 @@ QStringList QHelpCollectionHandler::files(const QString &namespaceName,
     bindFilterQuery(m_query, bindCount, filterName);
 
     if (!m_query->exec())
-        return QStringList();
+        return{};
 
     QStringList fileNames;
     while (m_query->next()) {
@@ -1319,18 +1309,17 @@ QStringList QHelpCollectionHandler::files(const QString &namespaceName,
                          + QLatin1Char('/')
                          + m_query->value(1).toString());
     }
-
     return fileNames;
 }
 
 QUrl QHelpCollectionHandler::findFile(const QUrl &url, const QStringList &filterAttributes) const
 {
     if (!isDBOpened())
-        return QUrl();
+        return {};
 
     const QString namespaceName = namespaceForFile(url, filterAttributes);
     if (namespaceName.isEmpty())
-        return QUrl();
+        return {};
 
     QUrl result = url;
     result.setAuthority(namespaceName);
@@ -1340,11 +1329,11 @@ QUrl QHelpCollectionHandler::findFile(const QUrl &url, const QStringList &filter
 QUrl QHelpCollectionHandler::findFile(const QUrl &url, const QString &filterName) const
 {
     if (!isDBOpened())
-        return QUrl();
+        return {};
 
     const QString namespaceName = namespaceForFile(url, filterName);
     if (namespaceName.isEmpty())
-        return QUrl();
+        return {};
 
     QUrl result = url;
     result.setAuthority(namespaceName);
@@ -1354,11 +1343,11 @@ QUrl QHelpCollectionHandler::findFile(const QUrl &url, const QString &filterName
 QByteArray QHelpCollectionHandler::fileData(const QUrl &url) const
 {
     if (!isDBOpened())
-        return QByteArray();
+        return {};
 
     const QString namespaceName = namespaceForFile(url, QString());
     if (namespaceName.isEmpty())
-        return QByteArray();
+        return {};
 
     const FileInfo fileInfo = extractFileInfo(url);
 
@@ -1366,9 +1355,9 @@ QByteArray QHelpCollectionHandler::fileData(const QUrl &url) const
     const QString absFileName = absoluteDocPath(docInfo.fileName);
 
     QHelpDBReader reader(absFileName, QHelpGlobal::uniquifyConnectionName(
-                             docInfo.fileName, const_cast<QHelpCollectionHandler *>(this)), nullptr);
+                         docInfo.fileName, const_cast<QHelpCollectionHandler *>(this)), nullptr);
     if (!reader.init())
-        return QByteArray();
+        return {};
 
     return reader.fileData(fileInfo.folderName, fileInfo.fileName);
 }
@@ -1412,7 +1401,6 @@ QStringList QHelpCollectionHandler::indicesForFilter(const QStringList &filterAt
     return indices;
 }
 
-
 QStringList QHelpCollectionHandler::indicesForFilter(const QString &filterName) const
 {
     QStringList indices;
@@ -1450,7 +1438,7 @@ QStringList QHelpCollectionHandler::indicesForFilter(const QString &filterName)
 static QString getTitle(const QByteArray &contents)
 {
     if (!contents.size())
-        return QString();
+        return {};
 
     int depth = 0;
     QString link;
@@ -1468,7 +1456,7 @@ QList<QHelpCollectionHandler::ContentsData> QHelpCollectionHandler::contentsForF
         const QStringList &filterAttributes) const
 {
     if (!isDBOpened())
-        return QList<ContentsData>();
+        return {};
 
     const QString filterlessQuery = QString::fromLatin1(
                 "SELECT DISTINCT "
@@ -1524,14 +1512,13 @@ QList<QHelpCollectionHandler::ContentsData> QHelpCollectionHandler::contentsForF
             result.append(it.value());
         }
     }
-
     return result;
 }
 
 QList<QHelpCollectionHandler::ContentsData> QHelpCollectionHandler::contentsForFilter(const QString &filterName) const
 {
     if (!isDBOpened())
-        return QList<ContentsData>();
+        return {};
 
     const QString filterlessQuery = QString::fromLatin1(
                 "SELECT DISTINCT "
@@ -1549,8 +1536,7 @@ QList<QHelpCollectionHandler::ContentsData> QHelpCollectionHandler::contentsForF
                 "AND ContentsTable.NamespaceId = NamespaceTable.Id "
                 "AND VersionTable.NamespaceId = NamespaceTable.Id");
 
-    const QString filterQuery = filterlessQuery
-            + prepareFilterQuery(filterName);
+    const QString filterQuery = filterlessQuery + prepareFilterQuery(filterName);
 
     m_query->prepare(filterQuery);
     bindFilterQuery(m_query, 0, filterName);
@@ -1583,7 +1569,6 @@ QList<QHelpCollectionHandler::ContentsData> QHelpCollectionHandler::contentsForF
             result.append(it.value());
         }
     }
-
     return result;
 }
 
@@ -1618,7 +1603,6 @@ QVariant QHelpCollectionHandler::customValue(const QString &key,
         m_query->clear();
         return value;
     }
-
     return defaultValue;
 }
 
@@ -1690,7 +1674,6 @@ bool QHelpCollectionHandler::registerFileAttributeSets(const QList<QStringList>
         ++attributeSetId;
 
         for (const QString &attribute : attributeSet) {
-
             m_query->prepare(QLatin1String("SELECT Id FROM FilterAttributeTable WHERE Name=?"));
             m_query->bindValue(0, attribute);
 
@@ -1747,9 +1730,8 @@ QStringList QHelpCollectionHandler::filterAttributes(const QString &filterName)
 
 QList<QStringList> QHelpCollectionHandler::filterAttributeSets(const QString &namespaceName) const
 {
-    QList<QStringList> result;
     if (!isDBOpened())
-        return result;
+        return {};
 
     m_query->prepare(QLatin1String(
                          "SELECT "
@@ -1766,6 +1748,7 @@ QList<QStringList> QHelpCollectionHandler::filterAttributeSets(const QString &na
     m_query->bindValue(0, namespaceName);
     m_query->exec();
     int oldId = -1;
+    QList<QStringList> result;
     while (m_query->next()) {
         const int id = m_query->value(0).toInt();
         if (id != oldId) {
@@ -1777,14 +1760,13 @@ QList<QStringList> QHelpCollectionHandler::filterAttributeSets(const QString &na
 
     if (result.isEmpty())
         result.append(QStringList());
-
     return result;
 }
 
 QString QHelpCollectionHandler::namespaceVersion(const QString &namespaceName) const
 {
     if (!m_query)
-        return QString();
+        return {};
 
     m_query->prepare(QLatin1String("SELECT "
                                        "VersionTable.Version "
@@ -1795,11 +1777,10 @@ QString QHelpCollectionHandler::namespaceVersion(const QString &namespaceName) c
                                    "AND NamespaceTable.Id = VersionTable.NamespaceId"));
     m_query->bindValue(0, namespaceName);
     if (!m_query->exec() || !m_query->next())
-        return QString();
+        return {};
 
     const QString ret = m_query->value(0).toString();
     m_query->clear();
-
     return ret;
 }
 
@@ -1853,10 +1834,8 @@ int QHelpCollectionHandler::registerVirtualFolder(const QString &folderName, int
         emit error(tr("Cannot register virtual folder '%1'.").arg(folderName));
         return -1;
     }
-
     if (registerComponent(folderName, namespaceId) < 0)
         return -1;
-
     return virtualId;
 }
 
@@ -1943,7 +1922,6 @@ bool QHelpCollectionHandler::registerIndexAndNamespaceFilterTables(
 
     if (createDefaultVersionFilter)
         createVersionFilter(reader.version());
-
     return true;
 }
 
@@ -1961,7 +1939,7 @@ void QHelpCollectionHandler::createVersionFilter(const QString &version)
         return;
 
     QHelpFilterData filterData;
-    filterData.setVersions(QList<QVersionNumber>() << versionNumber);
+    filterData.setVersions({versionNumber});
     setFilterData(filterName, filterData);
 }
 
@@ -2279,55 +2257,44 @@ QUrl QHelpCollectionHandler::buildQUrl(const QString &ns, const QString &folder,
 }
 
 QMultiMap<QString, QUrl> QHelpCollectionHandler::linksForIdentifier(
-        const QString &id,
-        const QStringList &filterAttributes) const
+        const QString &id, const QStringList &filterAttributes) const
 {
     return linksForField(QLatin1String("Identifier"), id, filterAttributes);
 }
 
 QMultiMap<QString, QUrl> QHelpCollectionHandler::linksForKeyword(
-        const QString &keyword,
-        const QStringList &filterAttributes) const
+        const QString &keyword, const QStringList &filterAttributes) const
 {
     return linksForField(QLatin1String("Name"), keyword, filterAttributes);
 }
 
 QList<QHelpLink> QHelpCollectionHandler::documentsForIdentifier(
-        const QString &id,
-        const QStringList &filterAttributes) const
+        const QString &id, const QStringList &filterAttributes) const
 {
     return documentsForField(QLatin1String("Identifier"), id, filterAttributes);
 }
 
 QList<QHelpLink> QHelpCollectionHandler::documentsForKeyword(
-        const QString &keyword,
-        const QStringList &filterAttributes) const
+        const QString &keyword, const QStringList &filterAttributes) const
 {
     return documentsForField(QLatin1String("Name"), keyword, filterAttributes);
 }
 
-QMultiMap<QString, QUrl> QHelpCollectionHandler::linksForField(
-        const QString &fieldName,
-        const QString &fieldValue,
-        const QStringList &filterAttributes) const
+QMultiMap<QString, QUrl> QHelpCollectionHandler::linksForField(const QString &fieldName,
+        const QString &fieldValue, const QStringList &filterAttributes) const
 {
     QMultiMap<QString, QUrl> linkMap;
     const auto documents = documentsForField(fieldName, fieldValue, filterAttributes);
     for (const auto &document : documents)
         linkMap.insert(document.title, document.url);
-
     return linkMap;
 }
 
-QList<QHelpLink> QHelpCollectionHandler::documentsForField(
-        const QString &fieldName,
-        const QString &fieldValue,
-        const QStringList &filterAttributes) const
+QList<QHelpLink> QHelpCollectionHandler::documentsForField(const QString &fieldName,
+        const QString &fieldValue, const QStringList &filterAttributes) const
 {
-    QList<QHelpLink> docList;
-
     if (!isDBOpened())
-        return docList;
+        return {};
 
     const QString filterlessQuery = QString::fromLatin1(
                 "SELECT "
@@ -2359,6 +2326,7 @@ QList<QHelpLink> QHelpCollectionHandler::documentsForField(
 
     m_query->exec();
 
+    QList<QHelpLink> docList;
     while (m_query->next()) {
         QString title = m_query->value(0).toString();
         if (title.isEmpty()) // generate a title + corresponding path
@@ -2374,55 +2342,44 @@ QList<QHelpLink> QHelpCollectionHandler::documentsForField(
 }
 
 QMultiMap<QString, QUrl> QHelpCollectionHandler::linksForIdentifier(
-        const QString &id,
-        const QString &filterName) const
+        const QString &id, const QString &filterName) const
 {
     return linksForField(QLatin1String("Identifier"), id, filterName);
 }
 
 QMultiMap<QString, QUrl> QHelpCollectionHandler::linksForKeyword(
-        const QString &keyword,
-        const QString &filterName) const
+        const QString &keyword, const QString &filterName) const
 {
     return linksForField(QLatin1String("Name"), keyword, filterName);
 }
 
 QList<QHelpLink> QHelpCollectionHandler::documentsForIdentifier(
-        const QString &id,
-        const QString &filterName) const
+        const QString &id, const QString &filterName) const
 {
     return documentsForField(QLatin1String("Identifier"), id, filterName);
 }
 
 QList<QHelpLink> QHelpCollectionHandler::documentsForKeyword(
-        const QString &keyword,
-        const QString &filterName) const
+        const QString &keyword, const QString &filterName) const
 {
     return documentsForField(QLatin1String("Name"), keyword, filterName);
 }
 
-QMultiMap<QString, QUrl> QHelpCollectionHandler::linksForField(
-        const QString &fieldName,
-        const QString &fieldValue,
-        const QString &filterName) const
+QMultiMap<QString, QUrl> QHelpCollectionHandler::linksForField(const QString &fieldName,
+        const QString &fieldValue, const QString &filterName) const
 {
     QMultiMap<QString, QUrl> linkMap;
     const auto documents = documentsForField(fieldName, fieldValue, filterName);
     for (const auto &document : documents)
         linkMap.insert(document.title, document.url);
-
     return linkMap;
 }
 
-QList<QHelpLink> QHelpCollectionHandler::documentsForField(
-        const QString &fieldName,
-        const QString &fieldValue,
-        const QString &filterName) const
+QList<QHelpLink> QHelpCollectionHandler::documentsForField(const QString &fieldName,
+        const QString &fieldValue, const QString &filterName) const
 {
-    QList<QHelpLink> docList;
-
     if (!isDBOpened())
-        return docList;
+        return {};
 
     const QString filterlessQuery = QString::fromLatin1(
                 "SELECT "
@@ -2451,6 +2408,7 @@ QList<QHelpLink> QHelpCollectionHandler::documentsForField(
 
     m_query->exec();
 
+    QList<QHelpLink> docList;
     while (m_query->next()) {
         QString title = m_query->value(0).toString();
         if (title.isEmpty()) // generate a title + corresponding path
@@ -2489,13 +2447,7 @@ QStringList QHelpCollectionHandler::namespacesForFilter(const QString &filterNam
 
     while (m_query->next())
         namespaceList.append(m_query->value(0).toString());
-
     return namespaceList;
 }
 
-void QHelpCollectionHandler::setReadOnly(bool readOnly)
-{
-    m_readOnly = readOnly;
-}
-
 QT_END_NAMESPACE
diff --git a/src/assistant/help/qhelpcollectionhandler_p.h b/src/assistant/help/qhelpcollectionhandler_p.h
index 28221f444..6afe36533 100644
--- a/src/assistant/help/qhelpcollectionhandler_p.h
+++ b/src/assistant/help/qhelpcollectionhandler_p.h
@@ -60,7 +60,7 @@ public:
     explicit QHelpCollectionHandler(const QString &collectionFile, QObject *parent = nullptr);
     ~QHelpCollectionHandler();
 
-    QString collectionFile() const;
+    QString collectionFile() const { return m_collectionFile; }
 
     bool openCollectionFile();
     bool copyCollectionFile(const QString &fileName);
@@ -163,7 +163,7 @@ public:
 
     QStringList namespacesForFilter(const QString &filterName) const;
 
-    void setReadOnly(bool readOnly);
+    void setReadOnly(bool readOnly) { m_readOnly = readOnly; }
 
     static QUrl buildQUrl(const QString &ns, const QString &folder,
                           const QString &relFileName, const QString &anchor);
diff --git a/src/assistant/help/qhelpcontentitem.cpp b/src/assistant/help/qhelpcontentitem.cpp
index fbb4c5580..3c437efe0 100644
--- a/src/assistant/help/qhelpcontentitem.cpp
+++ b/src/assistant/help/qhelpcontentitem.cpp
@@ -63,6 +63,7 @@ int QHelpContentItem::childCount() const
 */
 int QHelpContentItem::row() const
 {
+    // TODO: Optimize by keeping the index internally.
     return d->parent ? d->parent->d->childItems.indexOf(const_cast<QHelpContentItem*>(this)) : 0;
 }
 
diff --git a/src/assistant/help/qhelpdbreader.cpp b/src/assistant/help/qhelpdbreader.cpp
index 39ad7dc26..a936340b0 100644
--- a/src/assistant/help/qhelpdbreader.cpp
+++ b/src/assistant/help/qhelpdbreader.cpp
@@ -14,8 +14,7 @@
 QT_BEGIN_NAMESPACE
 
 QHelpDBReader::QHelpDBReader(const QString &dbName)
-    : QObject(nullptr)
-    , m_dbName(dbName)
+    : m_dbName(dbName)
     , m_uniqueId(QHelpGlobal::uniquifyConnectionName(QLatin1String("QHelpDBReader"), this))
 {}
 
@@ -48,7 +47,6 @@ bool QHelpDBReader::init()
 
     m_initDone = true;
     m_query = new QSqlQuery(QSqlDatabase::database(m_uniqueId));
-
     return true;
 }
 
@@ -86,7 +84,7 @@ QString QHelpDBReader::virtualFolder() const
         if (m_query->next())
             return m_query->value(0).toString();
     }
-    return QString();
+    return {};
 }
 
 QString QHelpDBReader::version() const
@@ -101,7 +99,7 @@ QString QHelpDBReader::qtVersionHeuristic() const
 {
     const QString nameSpace = namespaceName();
     if (!nameSpace.startsWith(QLatin1String("org.qt-project.")))
-        return QString();
+        return {};
 
     // We take the namespace tail, starting from the last letter in namespace name.
     // We drop any non digit characters.
@@ -147,16 +145,15 @@ QString QHelpDBReader::qtVersionHeuristic() const
 
         return QString::fromUtf8("%1.%2.%3").arg(major).arg(minor).arg(patch);
     }
-
     return tail;
 }
 
 static bool isAttributeUsed(QSqlQuery *query, const QString &tableName, int attributeId)
 {
     query->prepare(QString::fromLatin1("SELECT FilterAttributeId "
-                     "FROM %1 "
-                     "WHERE FilterAttributeId = ? "
-                     "LIMIT 1").arg(tableName));
+                                       "FROM %1 "
+                                       "WHERE FilterAttributeId = ? "
+                                       "LIMIT 1").arg(tableName));
     query->bindValue(0, attributeId);
     query->exec();
     return query->next(); // if we got a result it means it was used
@@ -165,7 +162,7 @@ static bool isAttributeUsed(QSqlQuery *query, const QString &tableName, int attr
 static int filterDataCount(QSqlQuery *query, const QString &tableName)
 {
     query->exec(QString::fromLatin1("SELECT COUNT(*) FROM"
-              "(SELECT DISTINCT * FROM %1)").arg(tableName));
+                                    "(SELECT DISTINCT * FROM %1)").arg(tableName));
     query->next();
     return query->value(0).toInt();
 }
@@ -343,7 +340,6 @@ QHelpDBReader::IndexTable QHelpDBReader::indexTable() const
         for (int attributeId : usedAttributeIds)
             table.usedFilterAttributes.append(attributeIds.value(attributeId));
     }
-
     return table;
 }
 
@@ -445,9 +441,8 @@ QStringList QHelpDBReader::filterAttributes(const QString &filterName) const
 QMultiMap<QString, QByteArray> QHelpDBReader::filesData(const QStringList &filterAttributes,
                                                         const QString &extensionFilter) const
 {
-    QMultiMap<QString, QByteArray> result;
     if (!m_query)
-        return result;
+        return {};
 
     QString query;
     QString extension;
@@ -489,25 +484,22 @@ QMultiMap<QString, QByteArray> QHelpDBReader::filesData(const QStringList &filte
         }
     }
     m_query->exec(query);
+    QMultiMap<QString, QByteArray> result;
     while (m_query->next())
         result.insert(m_query->value(0).toString(), qUncompress(m_query->value(1).toByteArray()));
-
     return result;
 }
 
 QVariant QHelpDBReader::metaData(const QString &name) const
 {
-    QVariant v;
     if (!m_query)
-        return v;
+        return {};
 
-    m_query->prepare(QLatin1String("SELECT COUNT(Value), Value FROM MetaDataTable "
-        "WHERE Name=?"));
+    m_query->prepare(QLatin1String("SELECT COUNT(Value), Value FROM MetaDataTable WHERE Name=?"));
     m_query->bindValue(0, name);
-    if (m_query->exec() && m_query->next()
-        && m_query->value(0).toInt() == 1)
-        v = m_query->value(1);
-    return v;
+    if (m_query->exec() && m_query->next() && m_query->value(0).toInt() == 1)
+        return m_query->value(1);
+    return {};
 }
 
 QString QHelpDBReader::quote(const QString &string) const
diff --git a/src/assistant/help/qhelpengine.cpp b/src/assistant/help/qhelpengine.cpp
index 88ca829e7..e773018e5 100644
--- a/src/assistant/help/qhelpengine.cpp
+++ b/src/assistant/help/qhelpengine.cpp
@@ -25,7 +25,7 @@ public:
     QHelpSearchEngine *searchEngine = nullptr;
 
     bool m_isApplyCurrentFilterScheduled = false;
-    QHelpEngineCore *m_helpEngineCore;
+    QHelpEngineCore *m_helpEngineCore = nullptr;
 };
 
 QHelpEnginePrivate::QHelpEnginePrivate(QHelpEngineCore *helpEngineCore)
@@ -110,7 +110,7 @@ QHelpIndexModel *QHelpEngine::indexModel() const
 QHelpContentWidget *QHelpEngine::contentWidget()
 {
     if (!d->contentWidget) {
-        d->contentWidget = new QHelpContentWidget();
+        d->contentWidget = new QHelpContentWidget;
         d->contentWidget->setModel(d->contentModel);
 #if QT_CONFIG(cursor)
         connect(d->contentModel, &QHelpContentModel::contentsCreationStarted, this, [this] {
@@ -130,7 +130,7 @@ QHelpContentWidget *QHelpEngine::contentWidget()
 QHelpIndexWidget *QHelpEngine::indexWidget()
 {
     if (!d->indexWidget) {
-        d->indexWidget = new QHelpIndexWidget();
+        d->indexWidget = new QHelpIndexWidget;
         d->indexWidget->setModel(d->indexModel);
 #if QT_CONFIG(cursor)
         connect(d->indexModel, &QHelpIndexModel::indexCreationStarted, this, [this] {
diff --git a/src/assistant/help/qhelpenginecore.cpp b/src/assistant/help/qhelpenginecore.cpp
index 372c86b25..acc890727 100644
--- a/src/assistant/help/qhelpenginecore.cpp
+++ b/src/assistant/help/qhelpenginecore.cpp
@@ -17,7 +17,7 @@ class QHelpEngineCorePrivate
 {
 public:
     QHelpEngineCorePrivate(const QString &collectionFile, QHelpEngineCore *helpEngineCore);
-    ~QHelpEngineCorePrivate();
+    ~QHelpEngineCorePrivate() { delete collectionHandler; }
 
     void init(const QString &collectionFile);
     bool setup();
@@ -42,11 +42,6 @@ QHelpEngineCorePrivate::QHelpEngineCorePrivate(const QString &collectionFile,
     init(collectionFile);
 }
 
-QHelpEngineCorePrivate::~QHelpEngineCorePrivate()
-{
-    delete collectionHandler;
-}
-
 void QHelpEngineCorePrivate::init(const QString &collectionFile)
 {
     if (collectionHandler)
@@ -68,15 +63,13 @@ bool QHelpEngineCorePrivate::setup()
     emit q->setupStarted();
 
     const QVariant readOnlyVariant = q->property("_q_readonly");
-    const bool readOnly = readOnlyVariant.isValid()
-            ? readOnlyVariant.toBool() : q->isReadOnly();
+    const bool readOnly = readOnlyVariant.isValid() ? readOnlyVariant.toBool() : q->isReadOnly();
     collectionHandler->setReadOnly(readOnly);
     const bool opened = collectionHandler->openCollectionFile();
     if (opened)
         q->currentFilter();
 
     emit q->setupFinished();
-
     return opened;
 }
 
@@ -301,10 +294,10 @@ QString QHelpEngineCore::namespaceName(const QString &documentationFileName)
 {
     QHelpDBReader reader(documentationFileName,
         QHelpGlobal::uniquifyConnectionName(QLatin1String("GetNamespaceName"),
-        QThread::currentThread()), nullptr);
+            QThread::currentThread()), nullptr); // TODO: Replace QThread with *this
     if (reader.init())
         return reader.namespaceName();
-    return QString();
+    return {};
 }
 
 /*!
@@ -347,13 +340,13 @@ bool QHelpEngineCore::unregisterDocumentation(const QString &namespaceName)
 QString QHelpEngineCore::documentationFileName(const QString &namespaceName)
 {
     if (!d->setup())
-        return QString();
+        return {};
 
     const QHelpCollectionHandler::FileInfo fileInfo =
             d->collectionHandler->registeredDocumentation(namespaceName);
 
     if (fileInfo.namespaceName.isEmpty())
-        return QString();
+        return {};
 
     if (QDir::isAbsolutePath(fileInfo.fileName))
         return fileInfo.fileName;
@@ -368,11 +361,10 @@ QString QHelpEngineCore::documentationFileName(const QString &namespaceName)
 */
 QStringList QHelpEngineCore::registeredDocumentations() const
 {
-    QStringList list;
     if (!d->setup())
-        return list;
-    const QHelpCollectionHandler::FileInfoList &docList
-            = d->collectionHandler->registeredDocumentations();
+        return {};
+    const auto &docList = d->collectionHandler->registeredDocumentations();
+    QStringList list;
     for (const QHelpCollectionHandler::FileInfo &info : docList)
         list.append(info.namespaceName);
     return list;
@@ -390,7 +382,7 @@ QStringList QHelpEngineCore::registeredDocumentations() const
 QStringList QHelpEngineCore::customFilters() const
 {
     if (!d->setup())
-        return QStringList();
+        return {};
     return d->collectionHandler->customFilters();
 }
 
@@ -441,7 +433,7 @@ bool QHelpEngineCore::removeCustomFilter(const QString &filterName)
 QStringList QHelpEngineCore::filterAttributes() const
 {
     if (!d->setup())
-        return QStringList();
+        return {};
     return d->collectionHandler->filterAttributes();
 }
 
@@ -456,7 +448,7 @@ QStringList QHelpEngineCore::filterAttributes() const
 QStringList QHelpEngineCore::filterAttributes(const QString &filterName) const
 {
     if (!d->setup())
-        return QStringList();
+        return {};
     return d->collectionHandler->filterAttributes(filterName);
 }
 
@@ -477,14 +469,12 @@ QStringList QHelpEngineCore::filterAttributes(const QString &filterName) const
 QString QHelpEngineCore::currentFilter() const
 {
     if (!d->setup())
-        return QString();
+        return {};
 
     if (d->currentFilter.isEmpty()) {
-        const QString &filter =
-            d->collectionHandler->customValue(QLatin1String("CurrentFilter"),
-                QString()).toString();
-        if (!filter.isEmpty()
-            && d->collectionHandler->customFilters().contains(filter))
+        const QString &filter = d->collectionHandler->customValue(
+                    QLatin1String("CurrentFilter"), QString()).toString();
+        if (!filter.isEmpty() && d->collectionHandler->customFilters().contains(filter))
             d->currentFilter = filter;
     }
     return d->currentFilter;
@@ -495,10 +485,8 @@ void QHelpEngineCore::setCurrentFilter(const QString &filterName)
     if (!d->setup() || filterName == d->currentFilter)
         return;
     d->currentFilter = filterName;
-    if (d->autoSaveFilter) {
-        d->collectionHandler->setCustomValue(QLatin1String("CurrentFilter"),
-            d->currentFilter);
-    }
+    if (d->autoSaveFilter)
+        d->collectionHandler->setCustomValue(QLatin1String("CurrentFilter"), d->currentFilter);
     emit currentFilterChanged(d->currentFilter);
 }
 
@@ -514,8 +502,7 @@ void QHelpEngineCore::setCurrentFilter(const QString &filterName)
 QList<QStringList> QHelpEngineCore::filterAttributeSets(const QString &namespaceName) const
 {
     if (!d->setup())
-        return QList<QStringList>();
-
+        return {};
     return d->collectionHandler->filterAttributeSets(namespaceName);
 }
 
@@ -614,8 +601,7 @@ QUrl QHelpEngineCore::findFile(const QUrl &url) const
 QByteArray QHelpEngineCore::fileData(const QUrl &url) const
 {
     if (!d->setup())
-        return QByteArray();
-
+        return {};
     return d->collectionHandler->fileData(url);
 }
 
@@ -628,9 +614,8 @@ QByteArray QHelpEngineCore::fileData(const QUrl &url) const
 */
 QList<QHelpLink> QHelpEngineCore::documentsForIdentifier(const QString &id) const
 {
-    return documentsForIdentifier(id, d->usesFilterEngine
-                                  ? d->filterEngine->activeFilter()
-                                  : d->currentFilter);
+    return documentsForIdentifier(
+            id, d->usesFilterEngine ? d->filterEngine->activeFilter() : d->currentFilter);
 }
 
 /*!
@@ -644,11 +629,10 @@ QList<QHelpLink> QHelpEngineCore::documentsForIdentifier(const QString &id) cons
 QList<QHelpLink> QHelpEngineCore::documentsForIdentifier(const QString &id, const QString &filterName) const
 {
     if (!d->setup())
-        return QList<QHelpLink>();
+        return {};
 
     if (d->usesFilterEngine)
         return d->collectionHandler->documentsForIdentifier(id, filterName);
-
     return d->collectionHandler->documentsForIdentifier(id, filterAttributes(filterName));
 }
 
@@ -661,9 +645,8 @@ QList<QHelpLink> QHelpEngineCore::documentsForIdentifier(const QString &id, cons
 */
 QList<QHelpLink> QHelpEngineCore::documentsForKeyword(const QString &keyword) const
 {
-    return documentsForKeyword(keyword, d->usesFilterEngine
-                               ? d->filterEngine->activeFilter()
-                               : d->currentFilter);
+    return documentsForKeyword(
+            keyword, d->usesFilterEngine ? d->filterEngine->activeFilter() : d->currentFilter);
 }
 
 /*!
@@ -677,11 +660,10 @@ QList<QHelpLink> QHelpEngineCore::documentsForKeyword(const QString &keyword) co
 QList<QHelpLink> QHelpEngineCore::documentsForKeyword(const QString &keyword, const QString &filterName) const
 {
     if (!d->setup())
-        return QList<QHelpLink>();
+        return {};
 
     if (d->usesFilterEngine)
         return d->collectionHandler->documentsForKeyword(keyword, filterName);
-
     return d->collectionHandler->documentsForKeyword(keyword, filterAttributes(filterName));
 }
 
@@ -708,7 +690,7 @@ bool QHelpEngineCore::removeCustomValue(const QString &key)
 QVariant QHelpEngineCore::customValue(const QString &key, const QVariant &defaultValue) const
 {
     if (!d->setup())
-        return QVariant();
+        return {};
     return d->collectionHandler->customValue(key, defaultValue);
 }
 
@@ -740,7 +722,7 @@ QVariant QHelpEngineCore::metaData(const QString &documentationFileName,
 
     if (reader.init())
         return reader.metaData(name);
-    return QVariant();
+    return {};
 }
 
 /*!
diff --git a/src/assistant/help/qhelpfilterdata.cpp b/src/assistant/help/qhelpfilterdata.cpp
index ed6d3e78a..2baa7ce3c 100644
--- a/src/assistant/help/qhelpfilterdata.cpp
+++ b/src/assistant/help/qhelpfilterdata.cpp
@@ -15,8 +15,7 @@ public:
         : QSharedData(other)
         , m_components(other.m_components)
         , m_versions(other.m_versions)
-    { }
-    ~QHelpFilterDataPrivate() = default;
+    {}
 
     QStringList m_components;
     QList<QVersionNumber> m_versions;
@@ -40,10 +39,7 @@ public:
 /*!
     Constructs the empty filter.
 */
-QHelpFilterData::QHelpFilterData()
-    : d(new QHelpFilterDataPrivate)
-{
-}
+QHelpFilterData::QHelpFilterData() : d(new QHelpFilterDataPrivate) { }
 
 /*!
     Constructs a copy of \a other.
@@ -65,7 +61,6 @@ QHelpFilterData::~QHelpFilterData() = default;
 */
 QHelpFilterData &QHelpFilterData::operator=(const QHelpFilterData &) = default;
 
-
 /*!
     Move-assigns \a other to this QHelpFilterData instance.
 */
@@ -80,8 +75,7 @@ QHelpFilterData &QHelpFilterData::operator=(QHelpFilterData &&) = default;
 
 bool QHelpFilterData::operator==(const QHelpFilterData &other) const
 {
-    return (d->m_components == other.d->m_components &&
-            d->m_versions == other.d->m_versions);
+    return (d->m_components == other.d->m_components && d->m_versions == other.d->m_versions);
 }
 
 /*!
diff --git a/src/assistant/help/qhelpfilterengine.cpp b/src/assistant/help/qhelpfilterengine.cpp
index bb6df822d..0253e7af0 100644
--- a/src/assistant/help/qhelpfilterengine.cpp
+++ b/src/assistant/help/qhelpfilterengine.cpp
@@ -123,7 +123,7 @@ QHelpFilterEngine::~QHelpFilterEngine()
 void QHelpFilterEngine::setCollectionHandler(QHelpCollectionHandler *collectionHandler)
 {
     d->m_collectionHandler = collectionHandler;
-    d->m_currentFilter = QString();
+    d->m_currentFilter.clear();
     d->m_needsSetup = true;
 }
 
@@ -134,7 +134,7 @@ void QHelpFilterEngine::setCollectionHandler(QHelpCollectionHandler *collectionH
 QMap<QString, QString> QHelpFilterEngine::namespaceToComponent() const
 {
     if (!d->setup())
-        return QMap<QString, QString>();
+        return {};
     return d->m_collectionHandler->namespaceToComponent();
 }
 
@@ -145,8 +145,7 @@ QMap<QString, QString> QHelpFilterEngine::namespaceToComponent() const
 QMap<QString, QVersionNumber> QHelpFilterEngine::namespaceToVersion() const
 {
     if (!d->setup())
-        return QMap<QString, QVersionNumber>();
-
+        return {};
     return d->m_collectionHandler->namespaceToVersion();
 }
 
@@ -156,7 +155,7 @@ QMap<QString, QVersionNumber> QHelpFilterEngine::namespaceToVersion() const
 QStringList QHelpFilterEngine::filters() const
 {
     if (!d->setup())
-        return QStringList();
+        return {};
     return d->m_collectionHandler->filters();
 }
 
@@ -167,7 +166,7 @@ QStringList QHelpFilterEngine::filters() const
 QStringList QHelpFilterEngine::availableComponents() const
 {
     if (!d->setup())
-        return QStringList();
+        return {};
     return d->m_collectionHandler->availableComponents();
 }
 
@@ -180,7 +179,7 @@ QStringList QHelpFilterEngine::availableComponents() const
 QList<QVersionNumber> QHelpFilterEngine::availableVersions() const
 {
     if (!d->setup())
-        return QList<QVersionNumber>();
+        return {};
     return d->m_collectionHandler->availableVersions();
 }
 
@@ -190,7 +189,7 @@ QList<QVersionNumber> QHelpFilterEngine::availableVersions() const
 QHelpFilterData QHelpFilterEngine::filterData(const QString &filterName) const
 {
     if (!d->setup())
-        return QHelpFilterData();
+        return {};
     return d->m_collectionHandler->filterData(filterName);
 }
 
@@ -227,7 +226,7 @@ bool QHelpFilterEngine::removeFilter(const QString &filterName)
 QString QHelpFilterEngine::activeFilter() const
 {
     if (!d->setup())
-        return QString();
+        return {};
     return d->m_currentFilter;
 }
 
@@ -253,7 +252,6 @@ bool QHelpFilterEngine::setActiveFilter(const QString &filterName)
             d->m_currentFilter);
 
     emit filterActivated(d->m_currentFilter);
-
     return true;
 }
 
@@ -264,7 +262,7 @@ bool QHelpFilterEngine::setActiveFilter(const QString &filterName)
 QStringList QHelpFilterEngine::namespacesForFilter(const QString &filterName) const
 {
     if (!d->setup())
-        return QStringList();
+        return {};
     return  d->m_collectionHandler->namespacesForFilter(filterName);
 }
 
@@ -292,7 +290,7 @@ QStringList QHelpFilterEngine::indices() const
 QStringList QHelpFilterEngine::indices(const QString &filterName) const
 {
     if (!d->setup())
-        return QStringList();
+        return {};
     return d->m_collectionHandler->indicesForFilter(filterName);
 }
 
diff --git a/src/assistant/help/qhelpfiltersettingswidget.cpp b/src/assistant/help/qhelpfiltersettingswidget.cpp
index cd4f2b47c..af0db2632 100644
--- a/src/assistant/help/qhelpfiltersettingswidget.cpp
+++ b/src/assistant/help/qhelpfiltersettingswidget.cpp
@@ -45,7 +45,6 @@ static QHelpFilterSettings readSettingsHelper(const QHelpFilterEngine *filterEng
         filterSettings.setFilter(filter, filterEngine->filterData(filter));
 
     filterSettings.setCurrentFilter(filterEngine->activeFilter());
-
     return filterSettings;
 }
 
@@ -59,7 +58,6 @@ static QMap<QString, QHelpFilterData> subtract(const QMap<QString, QHelpFilterDa
         if (itResult != result.end() && itSubtrahend.value() == itResult.value())
             result.erase(itResult);
     }
-
     return result;
 }
 
@@ -68,19 +66,15 @@ static bool applySettingsHelper(QHelpFilterEngine *filterEngine, const QHelpFilt
     bool changed = false;
     const QHelpFilterSettings oldSettings = readSettingsHelper(filterEngine);
 
-    const QMap<QString, QHelpFilterData> filtersToRemove = subtract(
-            oldSettings.filters(),
-            settings.filters());
-    const QMap<QString, QHelpFilterData> filtersToAdd = subtract(
-            settings.filters(),
-            oldSettings.filters());
+    const auto filtersToRemove = subtract(oldSettings.filters(), settings.filters());
+    const auto filtersToAdd = subtract(settings.filters(), oldSettings.filters());
 
     const QString &currentFilter = filterEngine->activeFilter();
 
     for (const QString &filter : filtersToRemove.keys()) {
         filterEngine->removeFilter(filter);
         if (currentFilter == filter && !filtersToAdd.contains(filter))
-            filterEngine->setActiveFilter(QString());
+            filterEngine->setActiveFilter({});
         changed = true;
     }
 
@@ -91,7 +85,6 @@ static bool applySettingsHelper(QHelpFilterEngine *filterEngine, const QHelpFilt
 
     if (changed)
         filterEngine->setActiveFilter(settings.currentFilter());
-
     return changed;
 }
 
@@ -114,11 +107,11 @@ static QList<QVersionNumber> stringListToVersions(const QStringList &versionList
 class QHelpFilterSettingsWidgetPrivate
 {
     QHelpFilterSettingsWidget *q_ptr;
-    Q_DECLARE_PUBLIC(QHelpFilterSettingsWidget)
+    Q_DECLARE_PUBLIC(QHelpFilterSettingsWidget) // TODO: remove Q_DECLARE_PUBLIC
 public:
     QHelpFilterSettingsWidgetPrivate() = default;
 
-    QHelpFilterSettings filterSettings() const;
+    QHelpFilterSettings filterSettings() const { return m_filterSettings; }
     void setFilterSettings(const QHelpFilterSettings &settings);
 
     void updateCurrentFilter();
@@ -127,11 +120,9 @@ public:
     void addFilterClicked();
     void renameFilterClicked();
     void removeFilterClicked();
-    void addFilter(const QString &filterName,
-                   const QHelpFilterData &filterData = QHelpFilterData());
+    void addFilter(const QString &filterName, const QHelpFilterData &filterData = {});
     void removeFilter(const QString &filterName);
-    QString getUniqueFilterName(const QString &windowTitle,
-                                const QString &initialFilterName);
+    QString getUniqueFilterName(const QString &windowTitle, const QString &initialFilterName);
     QString suggestedNewFilterName(const QString &initialFilterName) const;
 
     QMap<QString, QListWidgetItem *> m_filterToItem;
@@ -176,11 +167,6 @@ void QHelpFilterSettingsWidgetPrivate::setFilterSettings(const QHelpFilterSettin
     updateCurrentFilter();
 }
 
-QHelpFilterSettings QHelpFilterSettingsWidgetPrivate::filterSettings() const
-{
-    return m_filterSettings;
-}
-
 void QHelpFilterSettingsWidgetPrivate::updateCurrentFilter()
 {
     const QString &currentFilter = m_itemToFilter.value(m_ui.filterWidget->currentItem());
@@ -256,17 +242,15 @@ void QHelpFilterSettingsWidgetPrivate::removeFilterClicked()
         return;
 
     if (QMessageBox::question(q, QHelpFilterSettingsWidget::tr("Remove Filter"),
-                              QHelpFilterSettingsWidget::tr("Are you sure you want to remove the \"%1\" filter?")
-                              .arg(currentFilter),
-                              QMessageBox::Yes | QMessageBox::No)
-            != QMessageBox::Yes) {
+            QHelpFilterSettingsWidget::tr("Are you sure you want to remove the \"%1\" filter?")
+            .arg(currentFilter), QMessageBox::Yes | QMessageBox::No) != QMessageBox::Yes) {
         return;
     }
 
     removeFilter(currentFilter);
 
     if (m_filterSettings.currentFilter() == currentFilter)
-        m_filterSettings.setCurrentFilter(QString());
+        m_filterSettings.setCurrentFilter({});
 }
 
 void QHelpFilterSettingsWidgetPrivate::addFilter(const QString &filterName,
@@ -288,7 +272,6 @@ void QHelpFilterSettingsWidgetPrivate::removeFilter(const QString &filterName)
     m_itemToFilter.remove(item);
     m_filterToItem.remove(filterName);
     delete item;
-
     m_filterSettings.removeFilter(filterName);
 }
 
@@ -298,39 +281,32 @@ QString QHelpFilterSettingsWidgetPrivate::getUniqueFilterName(const QString &win
     Q_Q(QHelpFilterSettingsWidget);
 
     QString newFilterName = initialFilterName;
-    while (1) {
+    while (true) {
         QFilterNameDialog dialog(q);
         dialog.setWindowTitle(windowTitle);
         dialog.setFilterName(newFilterName);
         if (dialog.exec() == QDialog::Rejected)
-            return QString();
+            return {};
 
         newFilterName = dialog.filterName();
         if (!m_filterToItem.contains(newFilterName))
             break;
 
         if (QMessageBox::warning(q, QHelpFilterSettingsWidget::tr("Filter Exists"),
-                                 QHelpFilterSettingsWidget::tr("The filter \"%1\" already exists.")
-                                 .arg(newFilterName),
-                                 QMessageBox::Retry | QMessageBox::Cancel)
-                == QMessageBox::Cancel) {
-            return QString();
+                QHelpFilterSettingsWidget::tr("The filter \"%1\" already exists.").arg(newFilterName),
+                QMessageBox::Retry | QMessageBox::Cancel) == QMessageBox::Cancel) {
+            return {};
         }
     }
-
     return newFilterName;
 }
 
 QString QHelpFilterSettingsWidgetPrivate::suggestedNewFilterName(const QString &initialFilterName) const
 {
     QString newFilterName = initialFilterName;
-
     int counter = 1;
-    while (m_filterToItem.contains(newFilterName)) {
-        newFilterName = initialFilterName + QLatin1Char(' ')
-                + QString::number(++counter);
-    }
-
+    while (m_filterToItem.contains(newFilterName))
+        newFilterName = initialFilterName + QLatin1Char(' ') + QString::number(++counter);
     return newFilterName;
 }
 
@@ -375,13 +351,13 @@ QHelpFilterSettingsWidget::QHelpFilterSettingsWidget(QWidget *parent)
     d->m_ui.addButton->setIcon(QIcon(resourcePath + QLatin1String("/plus.png")));
     d->m_ui.removeButton->setIcon(QIcon(resourcePath + QLatin1String("/minus.png")));
 
-    connect(d->m_ui.componentWidget, &QOptionsWidget::optionSelectionChanged, this,
-            [this](const QStringList &options) {
+    connect(d->m_ui.componentWidget, &QOptionsWidget::optionSelectionChanged,
+            this, [this](const QStringList &options) {
         Q_D(QHelpFilterSettingsWidget);
         d->componentsChanged(options);
     });
-    connect(d->m_ui.versionWidget, &QOptionsWidget::optionSelectionChanged, this,
-            [this](const QStringList &options) {
+    connect(d->m_ui.versionWidget, &QOptionsWidget::optionSelectionChanged,
+            this, [this](const QStringList &options) {
         Q_D(QHelpFilterSettingsWidget);
         d->versionsChanged(options);
     });
@@ -390,25 +366,22 @@ QHelpFilterSettingsWidget::QHelpFilterSettingsWidget(QWidget *parent)
         Q_D(QHelpFilterSettingsWidget);
         d->updateCurrentFilter();
     });
-    connect(d->m_ui.filterWidget, &QListWidget::itemDoubleClicked, this,
-            [this](QListWidgetItem *) {
+    connect(d->m_ui.filterWidget, &QListWidget::itemDoubleClicked,
+            this, [this](QListWidgetItem *) {
         Q_D(QHelpFilterSettingsWidget);
         d->renameFilterClicked();
     });
 
     // TODO: repeat these actions on context menu
-    connect(d->m_ui.addButton, &QAbstractButton::clicked, this,
-            [this]() {
+    connect(d->m_ui.addButton, &QAbstractButton::clicked, this, [this] {
         Q_D(QHelpFilterSettingsWidget);
         d->addFilterClicked();
     });
-    connect(d->m_ui.renameButton, &QAbstractButton::clicked, this,
-            [this]() {
+    connect(d->m_ui.renameButton, &QAbstractButton::clicked, this, [this] {
         Q_D(QHelpFilterSettingsWidget);
         d->renameFilterClicked();
     });
-    connect(d->m_ui.removeButton, &QAbstractButton::clicked, this,
-            [this]() {
+    connect(d->m_ui.removeButton, &QAbstractButton::clicked, this, [this] {
         Q_D(QHelpFilterSettingsWidget);
         d->removeFilterClicked();
     });
diff --git a/src/assistant/help/qhelpindexwidget.cpp b/src/assistant/help/qhelpindexwidget.cpp
index 9d1df93f0..77b2ba9b5 100644
--- a/src/assistant/help/qhelpindexwidget.cpp
+++ b/src/assistant/help/qhelpindexwidget.cpp
@@ -231,7 +231,7 @@ QModelIndex QHelpIndexModel::filter(const QString &filter, const QString &wildca
 {
     if (filter.isEmpty()) {
         setStringList(d->indices);
-        return index(-1, 0, QModelIndex());
+        return index(-1, 0, {});
     }
 
     QStringList lst;
@@ -240,17 +240,17 @@ QModelIndex QHelpIndexModel::filter(const QString &filter, const QString &wildca
 
     if (!wildcard.isEmpty()) {
         auto re = QRegularExpression::wildcardToRegularExpression(wildcard,
-                                                                  QRegularExpression::UnanchoredWildcardConversion);
+                  QRegularExpression::UnanchoredWildcardConversion);
         const QRegularExpression regExp(re, QRegularExpression::CaseInsensitiveOption);
+        // TODO: Limit code repetition, see next loop in this body
         for (const QString &index : std::as_const(d->indices)) {
             if (index.contains(regExp)) {
                 lst.append(index);
                 if (perfectMatch == -1 && index.startsWith(filter, Qt::CaseInsensitive)) {
                     if (goodMatch == -1)
                         goodMatch = lst.size() - 1;
-                    if (filter.size() == index.size()){
+                    if (filter.size() == index.size())
                         perfectMatch = lst.size() - 1;
-                    }
                 } else if (perfectMatch > -1 && index == filter) {
                     perfectMatch = lst.size() - 1;
                 }
@@ -263,26 +263,22 @@ QModelIndex QHelpIndexModel::filter(const QString &filter, const QString &wildca
                 if (perfectMatch == -1 && index.startsWith(filter, Qt::CaseInsensitive)) {
                     if (goodMatch == -1)
                         goodMatch = lst.size() - 1;
-                    if (filter.size() == index.size()){
+                    if (filter.size() == index.size())
                         perfectMatch = lst.size() - 1;
-                    }
                 } else if (perfectMatch > -1 && index == filter) {
                     perfectMatch = lst.size() - 1;
                 }
             }
         }
-
     }
 
     if (perfectMatch == -1)
         perfectMatch = qMax(0, goodMatch);
 
     setStringList(lst);
-    return index(perfectMatch, 0, QModelIndex());
+    return index(perfectMatch, 0, {});
 }
 
-
-
 /*!
     \class QHelpIndexWidget
     \inmodule QtHelp
@@ -330,8 +326,7 @@ QHelpIndexWidget::QHelpIndexWidget()
 {
     setEditTriggers(QAbstractItemView::NoEditTriggers);
     setUniformItemSizes(true);
-    connect(this, &QAbstractItemView::activated,
-            this, &QHelpIndexWidget::showLink);
+    connect(this, &QAbstractItemView::activated, this, &QHelpIndexWidget::showLink);
 }
 
 void QHelpIndexWidget::showLink(const QModelIndex &index)
@@ -387,7 +382,7 @@ void QHelpIndexWidget::activateCurrentItem()
 */
 void QHelpIndexWidget::filterIndices(const QString &filter, const QString &wildcard)
 {
-    QHelpIndexModel *indexModel = qobject_cast<QHelpIndexModel*>(model());
+    QHelpIndexModel *indexModel = qobject_cast<QHelpIndexModel *>(model());
     if (!indexModel)
         return;
     const QModelIndex &idx = indexModel->filter(filter, wildcard);
diff --git a/src/assistant/help/qhelplink.h b/src/assistant/help/qhelplink.h
index 831c4a3dd..5c359188e 100644
--- a/src/assistant/help/qhelplink.h
+++ b/src/assistant/help/qhelplink.h
@@ -10,6 +10,7 @@
 
 QT_BEGIN_NAMESPACE
 
+// TODO: Qt 7.0 - pimpl or replace with std::pair? Replace struct with class.
 struct QHELP_EXPORT QHelpLink final
 {
     QUrl url;
diff --git a/src/assistant/help/qhelpsearchengine.cpp b/src/assistant/help/qhelpsearchengine.cpp
index a0a69865a..412eec457 100644
--- a/src/assistant/help/qhelpsearchengine.cpp
+++ b/src/assistant/help/qhelpsearchengine.cpp
@@ -48,9 +48,7 @@ public:
 
     QList<QHelpSearchResult> searchResults(int start, int end) const
     {
-        return indexReader ?
-               indexReader->searchResults(start, end) :
-               QList<QHelpSearchResult>();
+        return indexReader ? indexReader->searchResults(start, end) : QList<QHelpSearchResult>();
     }
 
     void updateIndex(bool reindex = false)
@@ -71,8 +69,7 @@ public:
         }
 
         indexWriter->cancelIndexing();
-        indexWriter->updateIndex(helpEngine->collectionFile(),
-                                 indexFilesFolder(), reindex);
+        indexWriter->updateIndex(helpEngine->collectionFile(), indexFilesFolder(), reindex);
     }
 
     void cancelIndexing()
@@ -114,8 +111,7 @@ public:
         QString indexFilesFolder = QLatin1String(".fulltextsearch");
         if (helpEngine && !helpEngine->collectionFile().isEmpty()) {
             QFileInfo fi(helpEngine->collectionFile());
-            indexFilesFolder = fi.absolutePath() + QDir::separator()
-                + QLatin1Char('.')
+            indexFilesFolder = fi.absolutePath() + QDir::separator() + QLatin1Char('.')
                 + fi.fileName().left(fi.fileName().lastIndexOf(QLatin1String(".qhc")));
         }
         return indexFilesFolder;
@@ -281,7 +277,6 @@ QHelpSearchQueryWidget* QHelpSearchEngine::queryWidget()
 {
     if (!d->queryWidget)
         d->queryWidget = new QHelpSearchQueryWidget();
-
     return d->queryWidget;
 }
 
@@ -292,7 +287,6 @@ QHelpSearchResultWidget* QHelpSearchEngine::resultWidget()
 {
     if (!d->resultWidget)
         d->resultWidget = new QHelpSearchResultWidget(this);
-
     return d->resultWidget;
 }
 
@@ -381,8 +375,7 @@ QT_WARNING_DISABLE_DEPRECATED
 */
 QList<QHelpSearchQuery> QHelpSearchEngine::query() const
 {
-    return QList<QHelpSearchQuery>() << QHelpSearchQuery(QHelpSearchQuery::DEFAULT,
-           d->m_searchInput.split(QChar::Space));
+    return {{QHelpSearchQuery::DEFAULT, d->m_searchInput.split(QChar::Space)}};
 }
 QT_WARNING_POP
 #endif // QT_DEPRECATED_SINCE(5, 9)
diff --git a/src/assistant/help/qhelpsearchindexreader.cpp b/src/assistant/help/qhelpsearchindexreader.cpp
index 381bf4a3c..75e578324 100644
--- a/src/assistant/help/qhelpsearchindexreader.cpp
+++ b/src/assistant/help/qhelpsearchindexreader.cpp
@@ -17,12 +17,25 @@ namespace fulltextsearch {
 class Reader
 {
 public:
-    void setIndexPath(const QString &path);
-    void addNamespaceAttributes(const QString &namespaceName, const QStringList &attributes);
-    void setFilterEngineNamespaceList(const QStringList &namespaceList);
+    void setIndexPath(const QString &path)
+    {
+        m_indexPath = path;
+        m_namespaceAttributes.clear();
+        m_filterEngineNamespaceList.clear();
+        m_useFilterEngine = false;
+    }
+    void addNamespaceAttributes(const QString &namespaceName, const QStringList &attributes)
+    {
+        m_namespaceAttributes.insert(namespaceName, attributes);
+    }
+    void setFilterEngineNamespaceList(const QStringList &namespaceList)
+    {
+        m_useFilterEngine = true;
+        m_filterEngineNamespaceList = namespaceList;
+    }
 
     void searchInDB(const QString &term);
-    QList<QHelpSearchResult> searchResults() const;
+    QList<QHelpSearchResult> searchResults() const { return m_searchResults; }
 
 private:
     QList<QHelpSearchResult> queryTable(const QSqlDatabase &db, const QString &tableName,
@@ -35,25 +48,6 @@ private:
     bool m_useFilterEngine = false;
 };
 
-void Reader::setIndexPath(const QString &path)
-{
-    m_indexPath = path;
-    m_namespaceAttributes.clear();
-    m_filterEngineNamespaceList.clear();
-    m_useFilterEngine = false;
-}
-
-void Reader::addNamespaceAttributes(const QString &namespaceName, const QStringList &attributes)
-{
-    m_namespaceAttributes.insert(namespaceName, attributes);
-}
-
-void Reader::setFilterEngineNamespaceList(const QStringList &namespaceList)
-{
-    m_useFilterEngine = true;
-    m_filterEngineNamespaceList = namespaceList;
-}
-
 static QString namespacePlaceholders(const QMultiMap<QString, QStringList> &namespaces)
 {
     QString placeholders;
@@ -147,7 +141,6 @@ QList<QHelpSearchResult> Reader::queryTable(const QSqlDatabase &db, const QStrin
         const QString &snippet = query.value(2).toString();
         results.append(QHelpSearchResult(url, title, snippet));
     }
-
     return results;
 }
 
@@ -167,7 +160,7 @@ void Reader::searchInDB(const QString &searchInput)
                     queryTable(db, QLatin1String("contents"), searchInput);
 
             // merge results form title and contents searches
-            m_searchResults = QList<QHelpSearchResult>();
+            m_searchResults.clear();
 
             QSet<QUrl> urls;
 
@@ -191,11 +184,6 @@ void Reader::searchInDB(const QString &searchInput)
     QSqlDatabase::removeDatabase(uniqueId);
 }
 
-QList<QHelpSearchResult> Reader::searchResults() const
-{
-    return m_searchResults;
-}
-
 static bool attributesMatchFilter(const QStringList &attributes, const QStringList &filter)
 {
     for (const QString &attribute : filter) {
diff --git a/src/assistant/help/qhelpsearchindexreader_p.h b/src/assistant/help/qhelpsearchindexreader_p.h
index 52e22ad35..a54df4ded 100644
--- a/src/assistant/help/qhelpsearchindexreader_p.h
+++ b/src/assistant/help/qhelpsearchindexreader_p.h
@@ -25,6 +25,7 @@ QT_BEGIN_NAMESPACE
 
 namespace fulltextsearch {
 
+// TODO: Employ QFuture / QtConcurrent::run() ?
 class QHelpSearchIndexReader : public QThread
 {
     Q_OBJECT
diff --git a/src/assistant/help/qhelpsearchindexwriter.cpp b/src/assistant/help/qhelpsearchindexwriter.cpp
index f63b11260..ba2619f8c 100644
--- a/src/assistant/help/qhelpsearchindexwriter.cpp
+++ b/src/assistant/help/qhelpsearchindexwriter.cpp
@@ -72,13 +72,14 @@ Writer::Writer(const QString &path)
     const QString dbPath = m_dbDir + QLatin1Char('/') + QLatin1String(FTS_DB_NAME);
     m_db->setDatabaseName(dbPath);
     if (!m_db->open()) {
-        const QString &error = QHelpSearchIndexWriter::tr("Cannot open database \"%1\" using connection \"%2\": %3")
-                .arg(dbPath, m_uniqueId, m_db->lastError().text());
+        const QString &error = QHelpSearchIndexWriter::tr(
+                                       "Cannot open database \"%1\" using connection \"%2\": %3")
+                                       .arg(dbPath, m_uniqueId, m_db->lastError().text());
         qWarning("%s", qUtf8Printable(error));
         delete m_db;
         m_db = nullptr;
         QSqlDatabase::removeDatabase(m_uniqueId);
-        m_uniqueId = QString();
+        m_uniqueId.clear();
     } else {
         startTransaction();
     }
@@ -112,7 +113,6 @@ bool Writer::hasDB()
 
     query.prepare(QLatin1String("SELECT id FROM info LIMIT 1"));
     query.exec();
-
     return query.next();
 }
 
@@ -248,7 +248,6 @@ bool Writer::hasNamespace(const QString &namespaceName)
     query.prepare(QLatin1String("SELECT id FROM info WHERE namespace = ? LIMIT 1"));
     query.addBindValue(namespaceName);
     query.exec();
-
     return query.next();
 }
 
@@ -294,18 +293,11 @@ void Writer::endTransaction()
         query.exec(QLatin1String("VACUUM"));
 }
 
-QHelpSearchIndexWriter::QHelpSearchIndexWriter()
-    : QThread()
-    , m_cancel(false)
-{
-}
-
 QHelpSearchIndexWriter::~QHelpSearchIndexWriter()
 {
     m_mutex.lock();
     this->m_cancel = true;
     m_mutex.unlock();
-
     wait();
 }
 
@@ -316,8 +308,7 @@ void QHelpSearchIndexWriter::cancelIndexing()
 }
 
 void QHelpSearchIndexWriter::updateIndex(const QString &collectionFile,
-                                         const QString &indexFilesFolder,
-                                         bool reindex)
+                                         const QString &indexFilesFolder, bool reindex)
 {
     wait();
     QMutexLocker lock(&m_mutex);
@@ -337,22 +328,19 @@ static const char IndexedNamespacesKey[] = "FTS5IndexedNamespaces";
 static QMap<QString, QDateTime> readIndexMap(const QHelpEngineCore &engine)
 {
     QMap<QString, QDateTime> indexMap;
-    QDataStream dataStream(engine.customValue(
-                QLatin1String(IndexedNamespacesKey)).toByteArray());
+    QDataStream dataStream(engine.customValue(QLatin1String(IndexedNamespacesKey)).toByteArray());
     dataStream >> indexMap;
     return indexMap;
 }
 
-static bool writeIndexMap(QHelpEngineCore *engine,
-    const QMap<QString, QDateTime> &indexMap)
+static bool writeIndexMap(QHelpEngineCore *engine, const QMap<QString, QDateTime> &indexMap)
 {
     QByteArray data;
 
     QDataStream dataStream(&data, QIODevice::ReadWrite);
     dataStream << indexMap;
 
-    return engine->setCustomValue(
-                QLatin1String(IndexedNamespacesKey), data);
+    return engine->setCustomValue(QLatin1String(IndexedNamespacesKey), data);
 }
 
 static bool clearIndexMap(QHelpEngineCore *engine)
@@ -489,7 +477,7 @@ void QHelpSearchIndexWriter::run()
                 url.setPath(QLatin1Char('/') + virtualFolder + QLatin1Char('/') + file);
 
                 if (url.hasFragment())
-                    url.setFragment(QString());
+                    url.setFragment({});
 
                 const QString &fullFileName = url.toString();
                 if (!fullFileName.endsWith(QLatin1String(".html"))
diff --git a/src/assistant/help/qhelpsearchindexwriter_p.h b/src/assistant/help/qhelpsearchindexwriter_p.h
index af6ed3085..0e3b17451 100644
--- a/src/assistant/help/qhelpsearchindexwriter_p.h
+++ b/src/assistant/help/qhelpsearchindexwriter_p.h
@@ -24,12 +24,12 @@ class QSqlDatabase;
 
 namespace fulltextsearch {
 
+// TODO: Employ QFuture / QtConcurrent::run() ?
 class QHelpSearchIndexWriter : public QThread
 {
     Q_OBJECT
 
 public:
-    QHelpSearchIndexWriter();
     ~QHelpSearchIndexWriter() override;
 
     void cancelIndexing();
@@ -45,7 +45,7 @@ private:
 private:
     QMutex m_mutex;
 
-    bool m_cancel;
+    bool m_cancel = false;
     bool m_reindex;
     QString m_collectionFile;
     QString m_indexFilesFolder;
diff --git a/src/assistant/help/qhelpsearchquerywidget.cpp b/src/assistant/help/qhelpsearchquerywidget.cpp
index 4fb350ee9..d831370b9 100644
--- a/src/assistant/help/qhelpsearchquerywidget.cpp
+++ b/src/assistant/help/qhelpsearchquerywidget.cpp
@@ -23,7 +23,7 @@ private:
     struct QueryHistory {
         explicit QueryHistory() : curQuery(-1) {}
         QStringList queries;
-        int curQuery;
+        int curQuery = 0;
     };
 
     class CompleterModel : public QAbstractListModel
@@ -41,7 +41,7 @@ private:
         {
             if (!index.isValid() || index.row() >= termList.size()||
                 (role != Qt::EditRole && role != Qt::DisplayRole))
-                return QVariant();
+                return {};
             return termList.at(index.row());
         }
 
@@ -58,16 +58,7 @@ private:
         QStringList termList;
     };
 
-    QHelpSearchQueryWidgetPrivate()
-        : QObject()
-        , m_searchCompleter(new CompleterModel(this), this)
-    {
-    }
-
-    ~QHelpSearchQueryWidgetPrivate() override
-    {
-        // nothing todo
-    }
+    QHelpSearchQueryWidgetPrivate() : m_searchCompleter(new CompleterModel(this), this) {}
 
     void retranslate()
     {
@@ -128,7 +119,6 @@ private slots:
                     prevQuery();
                 return true;
             }
-
         }
         return QObject::eventFilter(ob, event);
     }
@@ -144,14 +134,10 @@ private slots:
 
     void nextQuery()
     {
-        nextOrPrevQuery(m_queries.queries.size() - 1, 1, m_nextQueryButton,
-                m_prevQueryButton);
+        nextOrPrevQuery(m_queries.queries.size() - 1, 1, m_nextQueryButton, m_prevQueryButton);
     }
 
-    void prevQuery()
-    {
-        nextOrPrevQuery(0, -1, m_prevQueryButton, m_nextQueryButton);
-    }
+    void prevQuery() { nextOrPrevQuery(0, -1, m_prevQueryButton, m_nextQueryButton); }
 
 private:
     friend class QHelpSearchQueryWidget;
@@ -188,13 +174,12 @@ private:
 */
 QHelpSearchQueryWidget::QHelpSearchQueryWidget(QWidget *parent)
     : QWidget(parent)
+    , d(new QHelpSearchQueryWidgetPrivate)
 {
-    d = new QHelpSearchQueryWidgetPrivate();
-
     QVBoxLayout *vLayout = new QVBoxLayout(this);
-    vLayout->setContentsMargins(QMargins());
+    vLayout->setContentsMargins({});
 
-    QHBoxLayout* hBoxLayout = new QHBoxLayout();
+    QHBoxLayout* hBoxLayout = new QHBoxLayout;
     d->m_searchLabel = new QLabel(this);
     d->m_lineEdit = new QLineEdit(this);
     d->m_lineEdit->setClearButtonEnabled(true);
@@ -265,8 +250,7 @@ QT_WARNING_DISABLE_DEPRECATED
 */
 QList<QHelpSearchQuery> QHelpSearchQueryWidget::query() const
 {
-    return QList<QHelpSearchQuery>() << QHelpSearchQuery(QHelpSearchQuery::DEFAULT,
-           searchInput().split(QChar::Space, Qt::SkipEmptyParts));
+    return {{QHelpSearchQuery::DEFAULT, searchInput().split(QChar::Space, Qt::SkipEmptyParts)}};
 }
 
 /*!
@@ -293,7 +277,7 @@ QT_WARNING_POP
 QString QHelpSearchQueryWidget::searchInput() const
 {
     if (d->m_queries.queries.isEmpty())
-        return QString();
+        return {};
     return d->m_queries.queries.last();
 }
 
@@ -309,9 +293,7 @@ QString QHelpSearchQueryWidget::searchInput() const
 void QHelpSearchQueryWidget::setSearchInput(const QString &searchInput)
 {
     d->m_lineEdit->clear();
-
     d->m_lineEdit->setText(searchInput);
-
     d->searchRequested();
 }
 
diff --git a/src/assistant/help/qhelpsearchresult.cpp b/src/assistant/help/qhelpsearchresult.cpp
index 736c169b0..a813249d7 100644
--- a/src/assistant/help/qhelpsearchresult.cpp
+++ b/src/assistant/help/qhelpsearchresult.cpp
@@ -34,9 +34,7 @@ public:
 /*!
     Constructs a new empty QHelpSearchResult.
 */
-QHelpSearchResult::QHelpSearchResult()
-    : d(new QHelpSearchResultData)
-{}
+QHelpSearchResult::QHelpSearchResult() : d(new QHelpSearchResultData) { }
 
 /*!
     Constructs a copy of \a other.
diff --git a/src/assistant/help/qhelpsearchresultwidget.cpp b/src/assistant/help/qhelpsearchresultwidget.cpp
index 6c655b1a9..4fcc2d222 100644
--- a/src/assistant/help/qhelpsearchresultwidget.cpp
+++ b/src/assistant/help/qhelpsearchresultwidget.cpp
@@ -24,8 +24,7 @@ public:
     QResultWidget(QWidget *parent = nullptr)
         : QTextBrowser(parent)
     {
-        connect(this, &QTextBrowser::anchorClicked,
-                this, &QResultWidget::requestShowLink);
+        connect(this, &QTextBrowser::anchorClicked, this, &QResultWidget::requestShowLink);
         setContextMenuPolicy(Qt::NoContextMenu);
         setLinkColor(palette().color(QPalette::Link));
     }
@@ -34,7 +33,8 @@ public:
     void setLinkColor(const QColor &color)
     {
         m_linkColor = color;
-        const QString sheet = QString::fromLatin1("a { text-decoration: underline; color: %1 }").arg(m_linkColor.name());
+        const QString sheet = QString::fromLatin1("a { text-decoration: underline; color: %1 }")
+                                      .arg(m_linkColor.name());
         document()->setDefaultStyleSheet(sheet);
     }
 
@@ -73,7 +73,6 @@ public:
         }
 
         str << "</body></html>";
-
         setHtml(htmlFile);
     }
 
@@ -87,7 +86,6 @@ private:
     QColor m_linkColor;
 };
 
-
 class QHelpSearchResultWidgetPrivate : public QObject
 {
     Q_OBJECT
@@ -126,20 +124,12 @@ private slots:
         updateHitRange();
     }
 
-    void indexingStarted()
-    {
-        isIndexing = true;
-    }
-
-    void indexingFinished()
-    {
-        isIndexing = false;
-    }
+    void indexingStarted() { isIndexing = true; }
+    void indexingFinished() { isIndexing = false; }
 
 private:
     QHelpSearchResultWidgetPrivate(QHelpSearchEngine *engine)
-        : QObject()
-        , searchEngine(engine)
+        : searchEngine(engine)
     {
         connect(searchEngine.data(), &QHelpSearchEngine::indexingStarted,
                 this, &QHelpSearchResultWidgetPrivate::indexingStarted);
@@ -154,13 +144,12 @@ private:
 
     QToolButton* setupToolButton(const QString &iconPath)
     {
-        QToolButton *button = new QToolButton();
+        QToolButton *button = new QToolButton;
         button->setEnabled(false);
         button->setAutoRaise(true);
         button->setIcon(QIcon(iconPath));
         button->setIconSize(QSize(12, 12));
         button->setMaximumSize(QSize(16, 16));
-
         return button;
     }
 
@@ -176,11 +165,12 @@ private:
                 last = qMin(resultFirstToShow + ResultsRange, count);
                 first = resultFirstToShow + 1;
             }
-            resultTextBrowser->showResultPage(searchEngine->searchResults(resultFirstToShow,
-                               last), isIndexing);
+            resultTextBrowser->showResultPage(searchEngine->searchResults(resultFirstToShow, last),
+                                              isIndexing);
         }
 
-        hitsLabel->setText(QHelpSearchResultWidget::tr("%1 - %2 of %n Hits", nullptr, count).arg(first).arg(last));
+        hitsLabel->setText(QHelpSearchResultWidget::tr("%1 - %2 of %n Hits", nullptr, count)
+                                   .arg(first).arg(last));
         firstResultPage->setEnabled(resultFirstToShow);
         previousResultPage->setEnabled(resultFirstToShow);
         lastResultPage->setEnabled(count - last);
@@ -225,12 +215,12 @@ QHelpSearchResultWidget::QHelpSearchResultWidget(QHelpSearchEngine *engine)
     , d(new QHelpSearchResultWidgetPrivate(engine))
 {
     QVBoxLayout *vLayout = new QVBoxLayout(this);
-    vLayout->setContentsMargins(QMargins());
+    vLayout->setContentsMargins({});
     vLayout->setSpacing(0);
 
     QHBoxLayout *hBoxLayout = new QHBoxLayout();
 #ifndef Q_OS_MAC
-    hBoxLayout->setContentsMargins(QMargins());
+    hBoxLayout->setContentsMargins({});
     hBoxLayout->setSpacing(0);
 #endif
     hBoxLayout->addWidget(d->firstResultPage = d->setupToolButton(
@@ -298,7 +288,7 @@ QUrl QHelpSearchResultWidget::linkAt(const QPoint &point)
 {
     if (d->resultTextBrowser)
         return d->resultTextBrowser->anchorAt(point);
-    return QUrl();
+    return {};
 }
 
 QT_END_NAMESPACE
diff --git a/src/assistant/help/qoptionswidget.cpp b/src/assistant/help/qoptionswidget.cpp
index ee4bedb04..e42f852ad 100644
--- a/src/assistant/help/qoptionswidget.cpp
+++ b/src/assistant/help/qoptionswidget.cpp
@@ -23,29 +23,31 @@ public:
     }
 
 protected:
-    void paint(QPainter *painter,
-               const QStyleOptionViewItem &option,
-               const QModelIndex &index) const override {
+    void paint(QPainter *painter, const QStyleOptionViewItem &option,
+               const QModelIndex &index) const override
+    {
         if (isSeparator(index)) {
             QRect rect = option.rect;
             if (const QAbstractItemView *view = qobject_cast<const QAbstractItemView*>(option.widget))
                 rect.setWidth(view->viewport()->width());
             QStyleOption opt;
             opt.rect = rect;
-            m_widget->style()->drawPrimitive(QStyle::PE_IndicatorToolBarSeparator, &opt, painter, m_widget);
+            m_widget->style()->drawPrimitive(QStyle::PE_IndicatorToolBarSeparator, &opt, painter,
+                                             m_widget);
         } else {
             QItemDelegate::paint(painter, option, index);
         }
     }
 
-    QSize sizeHint(const QStyleOptionViewItem &option,
-                   const QModelIndex &index) const override {
+    QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const override
+    {
         if (isSeparator(index)) {
             int pm = m_widget->style()->pixelMetric(QStyle::PM_DefaultFrameWidth, nullptr, m_widget);
-            return QSize(pm, pm);
+            return {pm, pm};
         }
         return QItemDelegate::sizeHint(option, index);
     }
+
 private:
     QWidget *m_widget;
 };
@@ -67,18 +69,11 @@ QOptionsWidget::QOptionsWidget(QWidget *parent)
     m_listWidget->setItemDelegate(new ListWidgetDelegate(m_listWidget));
     QVBoxLayout *layout = new QVBoxLayout(this);
     layout->addWidget(m_listWidget);
-    layout->setContentsMargins(QMargins());
-
+    layout->setContentsMargins({});
     connect(m_listWidget, &QListWidget::itemChanged, this, &QOptionsWidget::itemChanged);
 }
 
-void QOptionsWidget::clear()
-{
-    setOptions(QStringList(), QStringList());
-}
-
-void QOptionsWidget::setOptions(const QStringList &validOptions,
-                                const QStringList &selectedOptions)
+void QOptionsWidget::setOptions(const QStringList &validOptions, const QStringList &selectedOptions)
 {
     m_listWidget->clear();
     m_optionToItem.clear();
@@ -102,10 +97,8 @@ void QOptionsWidget::setOptions(const QStringList &validOptions,
     for (const QString &option : m_invalidOptions)
         appendItem(option, false, true);
 
-    if ((validSelectedOptions.size() + m_invalidOptions.size())
-            && validUnselectedOptions.size()) {
+    if ((validSelectedOptions.size() + m_invalidOptions.size()) && validUnselectedOptions.size())
         appendSeparator();
-    }
 
     for (const QString &option : validUnselectedOptions) {
         appendItem(option, true, false);
@@ -114,16 +107,6 @@ void QOptionsWidget::setOptions(const QStringList &validOptions,
     }
 }
 
-QStringList QOptionsWidget::validOptions() const
-{
-    return m_validOptions;
-}
-
-QStringList QOptionsWidget::selectedOptions() const
-{
-    return m_selectedOptions;
-}
-
 void QOptionsWidget::setNoOptionText(const QString &text)
 {
     if (m_noOptionText == text)
@@ -195,9 +178,7 @@ void QOptionsWidget::itemChanged(QListWidgetItem *item)
     } else {
         return;
     }
-
     emit optionSelectionChanged(m_selectedOptions);
 }
 
-
 QT_END_NAMESPACE
diff --git a/src/assistant/help/qoptionswidget_p.h b/src/assistant/help/qoptionswidget_p.h
index b293311b9..0aef8bb7a 100644
--- a/src/assistant/help/qoptionswidget_p.h
+++ b/src/assistant/help/qoptionswidget_p.h
@@ -29,10 +29,10 @@ class QOptionsWidget : public QWidget
 public:
     QOptionsWidget(QWidget *parent = nullptr);
 
-    void clear();
+    void clear() { setOptions({}, {}); }
     void setOptions(const QStringList &validOptions, const QStringList &selectedOptions);
-    QStringList validOptions() const;
-    QStringList selectedOptions() const;
+    QStringList validOptions() const { return m_validOptions; }
+    QStringList selectedOptions() const { return m_selectedOptions; }
 
     void setNoOptionText(const QString &text);
     void setInvalidOptionText(const QString &text);
@@ -53,7 +53,7 @@ private:
     QStringList m_invalidOptions;
     QStringList m_selectedOptions;
     QMap<QString, QListWidgetItem *> m_optionToItem;
-    QMap<QListWidgetItem *, QString> m_itemToOption;
+    QMap<QListWidgetItem *, QString> m_itemToOption; // TODO: Replace with QHash
 };
 
 QT_END_NAMESPACE
diff --git a/src/assistant/qhelpgenerator/helpgenerator.cpp b/src/assistant/qhelpgenerator/helpgenerator.cpp
index df6b5e49e..6061b3460 100644
--- a/src/assistant/qhelpgenerator/helpgenerator.cpp
+++ b/src/assistant/qhelpgenerator/helpgenerator.cpp
@@ -330,7 +330,7 @@ bool HelpGeneratorPrivate::insertFileNotFoundFile()
         " VALUES (0, '', ?, '')"));
     m_query->bindValue(0, fileId);
     if (fileId > -1 && m_query->exec()) {
-        m_fileMap.insert(QString(), fileId);
+        m_fileMap.insert({}, fileId);
         return true;
     }
     return false;