Port majority of old-style connects (#237)

This provides more type safety and is future-proof.

20 files changed, 231 insertions, 445 deletions

diff --git a/src/base/QXmppLogger.cpp b/src/base/QXmppLogger.cpp
index 0580627d..10ee3471 100644
--- a/src/base/QXmppLogger.cpp
+++ b/src/base/QXmppLogger.cpp
@@ -62,12 +62,12 @@ static QString formatted(QXmppLogger::MessageType type, const QString& text)
 
 static void relaySignals(QXmppLoggable *from, QXmppLoggable *to)
 {
-    QObject::connect(from, SIGNAL(logMessage(QXmppLogger::MessageType,QString)),
-                     to, SIGNAL(logMessage(QXmppLogger::MessageType,QString)));
-    QObject::connect(from, SIGNAL(setGauge(QString,double)),
-                     to, SIGNAL(setGauge(QString,double)));
-    QObject::connect(from, SIGNAL(updateCounter(QString,qint64)),
-                     to, SIGNAL(updateCounter(QString,qint64)));
+    QObject::connect(from, &QXmppLoggable::logMessage,
+                     to, &QXmppLoggable::logMessage);
+    QObject::connect(from, &QXmppLoggable::setGauge,
+                     to, &QXmppLoggable::setGauge);
+    QObject::connect(from, &QXmppLoggable::updateCounter,
+                     to, &QXmppLoggable::updateCounter);
 }
 
 /// Constructs a new QXmppLoggable.
@@ -93,12 +93,12 @@ void QXmppLoggable::childEvent(QChildEvent *event)
     if (event->added()) {
         relaySignals(child, this);
     } else if (event->removed()) {
-        disconnect(child, SIGNAL(logMessage(QXmppLogger::MessageType,QString)),
-                this, SIGNAL(logMessage(QXmppLogger::MessageType,QString)));
-        disconnect(child, SIGNAL(setGauge(QString,double)),
-                this, SIGNAL(setGauge(QString,double)));
-        disconnect(child, SIGNAL(updateCounter(QString,qint64)),
-                this, SIGNAL(updateCounter(QString,qint64)));
+        disconnect(child, &QXmppLoggable::logMessage,
+                this, &QXmppLoggable::logMessage);
+        disconnect(child, &QXmppLoggable::setGauge,
+                this, &QXmppLoggable::setGauge);
+        disconnect(child, &QXmppLoggable::updateCounter,
+                this, &QXmppLoggable::updateCounter);
     }
 }
 /// \endcond
diff --git a/src/base/QXmppRtpChannel.cpp b/src/base/QXmppRtpChannel.cpp
index 7688ea3a..d4c20fad 100644
--- a/src/base/QXmppRtpChannel.cpp
+++ b/src/base/QXmppRtpChannel.cpp
@@ -251,11 +251,11 @@ QXmppRtpAudioChannel::QXmppRtpAudioChannel(QObject *parent)
 {
     auto *logParent = qobject_cast<QXmppLoggable*>(parent);
     if (logParent) {
-        connect(this, SIGNAL(logMessage(QXmppLogger::MessageType,QString)),
-                logParent, SIGNAL(logMessage(QXmppLogger::MessageType,QString)));
+        connect(this, &QXmppRtpAudioChannel::logMessage,
+                logParent, &QXmppLoggable::logMessage);
     }
     d->outgoingTimer = new QTimer(this);
-    connect(d->outgoingTimer, SIGNAL(timeout()), this, SLOT(writeDatagram()));
+    connect(d->outgoingTimer, &QTimer::timeout, this, &QXmppRtpAudioChannel::writeDatagram);
 
     // set supported codecs
     QXmppJinglePayloadType payload;
diff --git a/src/base/QXmppSocks.cpp b/src/base/QXmppSocks.cpp
index 833b3dac..ce8cdcc3 100644
--- a/src/base/QXmppSocks.cpp
+++ b/src/base/QXmppSocks.cpp
@@ -104,8 +104,8 @@ QXmppSocksClient::QXmppSocksClient(const QString &proxyHost, quint16 proxyPort,
     m_proxyPort(proxyPort),
     m_step(ConnectState)
 {
-    connect(this, SIGNAL(connected()), this, SLOT(slotConnected()));
-    connect(this, SIGNAL(readyRead()), this, SLOT(slotReadyRead()));
+    connect(this, &QAbstractSocket::connected, this, &QXmppSocksClient::slotConnected);
+    connect(this, &QIODevice::readyRead, this, &QXmppSocksClient::slotReadyRead);
 }
 
 void QXmppSocksClient::connectToHost(const QString &hostName, quint16 hostPort)
@@ -120,7 +120,7 @@ void QXmppSocksClient::slotConnected()
     m_step = ConnectState;
 
     // disconnect from signal
-    disconnect(this, SIGNAL(connected()), this, SLOT(slotConnected()));
+    disconnect(this, &QAbstractSocket::connected, this, &QXmppSocksClient::slotConnected);
 
     // send connect to server
     QByteArray buffer;
@@ -160,7 +160,7 @@ void QXmppSocksClient::slotReadyRead()
 
     } else if (m_step == CommandState) {
         // disconnect from signal
-        disconnect(this, SIGNAL(readyRead()), this, SLOT(slotReadyRead()));
+        disconnect(this, &QIODevice::readyRead, this, &QXmppSocksClient::slotReadyRead);
 
         // receive CONNECT response
         QByteArray buffer = read(3);
@@ -197,10 +197,10 @@ QXmppSocksServer::QXmppSocksServer(QObject *parent)
     : QObject(parent)
 {
     m_server = new QTcpServer(this);
-    connect(m_server, SIGNAL(newConnection()), this, SLOT(slotNewConnection()));
+    connect(m_server, &QTcpServer::newConnection, this, &QXmppSocksServer::slotNewConnection);
 
     m_server_v6 = new QTcpServer(this);
-    connect(m_server_v6, SIGNAL(newConnection()), this, SLOT(slotNewConnection()));
+    connect(m_server_v6, &QTcpServer::newConnection, this, &QXmppSocksServer::slotNewConnection);
 }
 
 void QXmppSocksServer::close()
@@ -236,7 +236,7 @@ void QXmppSocksServer::slotNewConnection()
 
     // register socket
     m_states.insert(socket, ConnectState);
-    connect(socket, SIGNAL(readyRead()), this, SLOT(slotReadyRead()));
+    connect(socket, &QIODevice::readyRead, this, &QXmppSocksServer::slotReadyRead);
 }
 
 void QXmppSocksServer::slotReadyRead()
@@ -292,7 +292,7 @@ void QXmppSocksServer::slotReadyRead()
 
     } else if (m_states.value(socket) == CommandState) {
         // disconnect from signals
-        disconnect(socket, SIGNAL(readyRead()), this, SLOT(slotReadyRead()));
+        disconnect(socket, &QIODevice::readyRead, this, &QXmppSocksServer::slotReadyRead);
 
         // receive command
         QByteArray buffer = socket->read(3);
diff --git a/src/base/QXmppStream.cpp b/src/base/QXmppStream.cpp
index 68496c93..0a2b0c4b 100644
--- a/src/base/QXmppStream.cpp
+++ b/src/base/QXmppStream.cpp
@@ -173,29 +173,15 @@ QSslSocket *QXmppStream::socket() const
 
 void QXmppStream::setSocket(QSslSocket *socket)
 {
-    bool check;
-    Q_UNUSED(check);
-
     d->socket = socket;
     if (!d->socket)
         return;
 
     // socket events
-    check = connect(socket, SIGNAL(connected()),
-                    this, SLOT(_q_socketConnected()));
-    Q_ASSERT(check);
-
-    check = connect(socket, SIGNAL(encrypted()),
-                    this, SLOT(_q_socketEncrypted()));
-    Q_ASSERT(check);
-
-    check = connect(socket, SIGNAL(error(QAbstractSocket::SocketError)),
-                    this, SLOT(_q_socketError(QAbstractSocket::SocketError)));
-    Q_ASSERT(check);
-
-    check = connect(socket, SIGNAL(readyRead()),
-                    this, SLOT(_q_socketReadyRead()));
-    Q_ASSERT(check);
+    connect(socket, &QAbstractSocket::connected, this, &QXmppStream::_q_socketConnected);
+    connect(socket, &QSslSocket::encrypted, this, &QXmppStream::_q_socketEncrypted);
+    connect(socket, QOverload<QAbstractSocket::SocketError>::of(&QSslSocket::error), this, &QXmppStream::_q_socketError);
+    connect(socket, &QIODevice::readyRead, this, &QXmppStream::_q_socketReadyRead);
 }
 
 void QXmppStream::_q_socketConnected()
diff --git a/src/base/QXmppStun.cpp b/src/base/QXmppStun.cpp
index e1a17077..5ac859d4 100644
--- a/src/base/QXmppStun.cpp
+++ b/src/base/QXmppStun.cpp
@@ -1111,7 +1111,7 @@ QXmppStunTransaction::QXmppStunTransaction(const QXmppStunMessage &request, QObj
     m_tries(0)
 {
     bool check;
-    Q_UNUSED(check);
+    Q_UNUSED(check)
 
     check = connect(this, SIGNAL(writeStun(QXmppStunMessage)),
                     receiver, SLOT(writeStun(QXmppStunMessage)));
@@ -1124,8 +1124,8 @@ QXmppStunTransaction::QXmppStunTransaction(const QXmppStunMessage &request, QObj
     // RTO timer
     m_retryTimer = new QTimer(this);
     m_retryTimer->setSingleShot(true);
-    check = connect(m_retryTimer, SIGNAL(timeout()),
-                    this, SLOT(retry()));
+    connect(m_retryTimer, &QTimer::timeout,
+                    this, &QXmppStunTransaction::retry);
 
     // send packet immediately
     m_retryTimer->start(0);
@@ -1182,26 +1182,21 @@ QXmppTurnAllocation::QXmppTurnAllocation(QObject *parent)
     m_lifetime(600),
     m_state(UnconnectedState)
 {
-    bool check;
-    Q_UNUSED(check);
 
     socket = new QUdpSocket(this);
-    check = connect(socket, SIGNAL(readyRead()),
-                    this, SLOT(readyRead()));
-    Q_ASSERT(check);
+    connect(socket, &QIODevice::readyRead,
+                    this, &QXmppTurnAllocation::readyRead);
 
     m_timer = new QTimer(this);
     m_timer->setSingleShot(true);
-    check = connect(m_timer, SIGNAL(timeout()),
-                    this, SLOT(refresh()));
-    Q_ASSERT(check);
+    connect(m_timer, &QTimer::timeout,
+                    this, &QXmppTurnAllocation::refresh);
 
     // channels are valid 600s, we refresh every 500s
     m_channelTimer = new QTimer(this);
     m_channelTimer->setInterval(500 * 1000);
-    check = connect(m_channelTimer, SIGNAL(timeout()),
-                    this, SLOT(refreshChannels()));
-    Q_ASSERT(check);
+    connect(m_channelTimer, &QTimer::timeout,
+                    this, &QXmppTurnAllocation::refreshChannels);
 }
 
 /// Destroys the TURN allocation.
@@ -1585,11 +1580,8 @@ QXmppUdpTransport::QXmppUdpTransport(QUdpSocket *socket, QObject *parent)
     : QXmppIceTransport(parent)
     , m_socket(socket)
 {
-    bool check;
-    Q_UNUSED(check);
 
-    check = connect(m_socket, SIGNAL(readyRead()), this, SLOT(readyRead()));
-    Q_ASSERT(check);
+    connect(m_socket, &QIODevice::readyRead, this, &QXmppUdpTransport::readyRead);
 }
 
 QXmppUdpTransport::~QXmppUdpTransport()
@@ -1868,8 +1860,6 @@ void QXmppIceComponentPrivate::performCheck(CandidatePair *pair, bool nominate)
 
 void QXmppIceComponentPrivate::setSockets(QList<QUdpSocket*> sockets)
 {
-    bool check;
-    Q_UNUSED(check);
 
     // clear previous candidates and sockets
     localCandidates.clear();
@@ -1884,9 +1874,8 @@ void QXmppIceComponentPrivate::setSockets(QList<QUdpSocket*> sockets)
         socket->setParent(q);
 
         auto *transport = new QXmppUdpTransport(socket, q);
-        check = QObject::connect(transport, SIGNAL(datagramReceived(QByteArray,QHostAddress,quint16)),
-                                 q, SLOT(handleDatagram(QByteArray,QHostAddress,quint16)));
-        Q_ASSERT(check);
+        QObject::connect(transport, &QXmppIceTransport::datagramReceived,
+                                 q, &QXmppIceComponent::handleDatagram);
 
         QXmppJingleCandidate candidate = transport->localCandidate(component);
 
@@ -1956,27 +1945,21 @@ void QXmppIceComponentPrivate::writeStun(const QXmppStunMessage &message, QXmppI
 QXmppIceComponent::QXmppIceComponent(int component, QXmppIcePrivate *config, QObject *parent)
     : QXmppLoggable(parent)
 {
-    bool check;
-    Q_UNUSED(check);
 
     d = new QXmppIceComponentPrivate(component, config, this);
 
     d->timer = new QTimer(this);
     d->timer->setInterval(500);
-    check = connect(d->timer, SIGNAL(timeout()),
-                    this, SLOT(checkCandidates()));
-    Q_ASSERT(check);
+    connect(d->timer, &QTimer::timeout,
+                    this, &QXmppIceComponent::checkCandidates);
 
     d->turnAllocation = new QXmppTurnAllocation(this);
-    check = connect(d->turnAllocation, SIGNAL(connected()),
-                    this, SLOT(turnConnected()));
-    Q_ASSERT(check);
-    check = connect(d->turnAllocation, SIGNAL(datagramReceived(QByteArray,QHostAddress,quint16)),
-                    this, SLOT(handleDatagram(QByteArray,QHostAddress,quint16)));
-    Q_ASSERT(check);
-    check = connect(d->turnAllocation, SIGNAL(disconnected()),
-                    this, SLOT(updateGatheringState()));
-    Q_ASSERT(check);
+    connect(d->turnAllocation, &QXmppTurnAllocation::connected,
+                    this, &QXmppIceComponent::turnConnected);
+    connect(d->turnAllocation, &QXmppIceTransport::datagramReceived,
+                    this, &QXmppIceComponent::handleDatagram);
+    connect(d->turnAllocation, &QXmppTurnAllocation::disconnected,
+                    this, &QXmppIceComponent::updateGatheringState);
 
     // calculate peer-reflexive candidate priority
     // see RFC 5245 -  7.1.2.1. PRIORITY and USE-CANDIDATE
@@ -2525,16 +2508,13 @@ QXmppIceConnection::QXmppIceConnection(QObject *parent)
     : QXmppLoggable(parent)
     , d(new QXmppIceConnectionPrivate())
 {
-    bool check;
 
     // timer to limit connection time to 30 seconds
     d->connectTimer = new QTimer(this);
     d->connectTimer->setInterval(30000);
     d->connectTimer->setSingleShot(true);
-    check = connect(d->connectTimer, SIGNAL(timeout()),
-                    this, SLOT(slotTimeout()));
-    Q_ASSERT(check);
-    Q_UNUSED(check);
+    connect(d->connectTimer, &QTimer::timeout,
+                    this, &QXmppIceConnection::slotTimeout);
 }
 
 QXmppIceConnection::~QXmppIceConnection()
@@ -2558,8 +2538,6 @@ QXmppIceComponent *QXmppIceConnection::component(int component)
 
 void QXmppIceConnection::addComponent(int component)
 {
-    bool check;
-    Q_UNUSED(check);
 
     if (d->components.contains(component)) {
         warning(QString("Already have component %1").arg(QString::number(component)));
@@ -2571,17 +2549,14 @@ void QXmppIceConnection::addComponent(int component)
     socket->d->setTurnUser(d->turnUser);
     socket->d->setTurnPassword(d->turnPassword);
 
-    check = connect(socket, SIGNAL(localCandidatesChanged()),
-                    this, SIGNAL(localCandidatesChanged()));
-    Q_ASSERT(check);
+    connect(socket, &QXmppIceComponent::localCandidatesChanged,
+                    this, &QXmppIceConnection::localCandidatesChanged);
 
-    check = connect(socket, SIGNAL(connected()),
-                    this, SLOT(slotConnected()));
-    Q_ASSERT(check);
+    connect(socket, &QXmppIceComponent::connected,
+                    this, &QXmppIceConnection::slotConnected);
 
-    check = connect(socket, SIGNAL(gatheringStateChanged()),
-                    this, SLOT(slotGatheringStateChanged()));
-    Q_ASSERT(check);
+    connect(socket, &QXmppIceComponent::gatheringStateChanged,
+                    this, &QXmppIceConnection::slotGatheringStateChanged);
 
     d->components[component] = socket;
 }
diff --git a/src/client/QXmppBookmarkManager.cpp b/src/client/QXmppBookmarkManager.cpp
index cd93782f..0cf993c3 100644
--- a/src/client/QXmppBookmarkManager.cpp
+++ b/src/client/QXmppBookmarkManager.cpp
@@ -145,18 +145,14 @@ bool QXmppBookmarkManager::setBookmarks(const QXmppBookmarkSet &bookmarks)
 /// \cond
 void QXmppBookmarkManager::setClient(QXmppClient *client)
 {
-    bool check;
-    Q_UNUSED(check);
 
     QXmppClientExtension::setClient(client);
 
-    check = connect(client, SIGNAL(connected()),
-                    this, SLOT(slotConnected()));
-    Q_ASSERT(check);
+    connect(client, &QXmppClient::connected,
+                    this, &QXmppBookmarkManager::slotConnected);
 
-    check = connect(client, SIGNAL(disconnected()),
-                    this, SLOT(slotDisconnected()));
-    Q_ASSERT(check);
+    connect(client, &QXmppClient::disconnected,
+                    this, &QXmppBookmarkManager::slotDisconnected);
 }
 
 bool QXmppBookmarkManager::handleStanza(const QDomElement &stanza)
diff --git a/src/client/QXmppCallManager.cpp b/src/client/QXmppCallManager.cpp
index 640dbf0e..f670aa02 100644
--- a/src/client/QXmppCallManager.cpp
+++ b/src/client/QXmppCallManager.cpp
@@ -204,7 +204,7 @@ void QXmppCallPrivate::handleRequest(const QXmppJingleIq &iq)
     } else if (iq.action() == QXmppJingleIq::SessionInfo) {
 
         // notify user
-        QTimer::singleShot(0, q, SIGNAL(ringing()));
+        QTimer::singleShot(0, q, &QXmppCall::ringing);
 
     } else if (iq.action() == QXmppJingleIq::SessionTerminate) {
 
@@ -291,7 +291,7 @@ void QXmppCallPrivate::handleRequest(const QXmppJingleIq &iq)
 QXmppCallPrivate::Stream *QXmppCallPrivate::createStream(const QString &media)
 {
     bool check;
-    Q_UNUSED(check);
+    Q_UNUSED(check)
     Q_ASSERT(manager);
 
     auto *stream = new Stream;
@@ -325,32 +325,26 @@ QXmppCallPrivate::Stream *QXmppCallPrivate::createStream(const QString &media)
     stream->connection->bind(QXmppIceComponent::discoverAddresses());
 
     // connect signals
-    check = QObject::connect(stream->connection, SIGNAL(localCandidatesChanged()),
-        q, SLOT(localCandidatesChanged()));
-    Q_ASSERT(check);
+    QObject::connect(stream->connection, &QXmppIceConnection::localCandidatesChanged,
+        q, &QXmppCall::localCandidatesChanged);
 
-    check = QObject::connect(stream->connection, SIGNAL(connected()),
-        q, SLOT(updateOpenMode()));
-    Q_ASSERT(check);
+    QObject::connect(stream->connection, &QXmppIceConnection::connected,
+        q, &QXmppCall::updateOpenMode);
 
-    check = QObject::connect(q, SIGNAL(stateChanged(QXmppCall::State)),
-        q, SLOT(updateOpenMode()));
-    Q_ASSERT(check);
+    QObject::connect(q, &QXmppCall::stateChanged,
+        q, &QXmppCall::updateOpenMode);
 
-    check = QObject::connect(stream->connection, SIGNAL(disconnected()),
-        q, SLOT(hangup()));
-    Q_ASSERT(check);
+    QObject::connect(stream->connection, &QXmppIceConnection::disconnected,
+        q, &QXmppCall::hangup);
 
     if (channelObject) {
         QXmppIceComponent *rtpComponent = stream->connection->component(RTP_COMPONENT);
 
-        check = QObject::connect(rtpComponent, SIGNAL(datagramReceived(QByteArray)),
+        QObject::connect(rtpComponent, SIGNAL(datagramReceived(QByteArray)),
                         channelObject, SLOT(datagramReceived(QByteArray)));
-        Q_ASSERT(check);
 
-        check = QObject::connect(channelObject, SIGNAL(sendDatagram(QByteArray)),
+        QObject::connect(channelObject, SIGNAL(sendDatagram(QByteArray)),
                         rtpComponent, SLOT(sendDatagram(QByteArray)));
-        Q_ASSERT(check);
     }
     return stream;
 }
@@ -445,7 +439,7 @@ void QXmppCallPrivate::terminate(QXmppJingleIq::Reason::Type reasonType)
     setState(QXmppCall::DisconnectingState);
 
     // schedule forceful termination in 5s
-    QTimer::singleShot(5000, q, SLOT(terminated()));
+    QTimer::singleShot(5000, q, &QXmppCall::terminated);
 }
 
 QXmppCall::QXmppCall(const QString &jid, QXmppCall::Direction direction, QXmppCallManager *parent)
@@ -761,22 +755,17 @@ bool QXmppCallManager::handleStanza(const QDomElement &element)
 
 void QXmppCallManager::setClient(QXmppClient *client)
 {
-    bool check;
-    Q_UNUSED(check);
 
     QXmppClientExtension::setClient(client);
 
-    check = connect(client, SIGNAL(disconnected()),
-                    this, SLOT(_q_disconnected()));
-    Q_ASSERT(check);
+    connect(client, &QXmppClient::disconnected,
+                    this, &QXmppCallManager::_q_disconnected);
 
-    check = connect(client, SIGNAL(iqReceived(QXmppIq)),
-                    this, SLOT(_q_iqReceived(QXmppIq)));
-    Q_ASSERT(check);
+    connect(client, &QXmppClient::iqReceived,
+                    this, &QXmppCallManager::_q_iqReceived);
 
-    check = connect(client, SIGNAL(presenceReceived(QXmppPresence)),
-                    this, SLOT(_q_presenceReceived(QXmppPresence)));
-    Q_ASSERT(check);
+    connect(client, &QXmppClient::presenceReceived,
+                    this, &QXmppCallManager::_q_presenceReceived);
 }
 /// \endcond
 
@@ -786,8 +775,6 @@ void QXmppCallManager::setClient(QXmppClient *client)
 
 QXmppCall *QXmppCallManager::call(const QString &jid)
 {
-    bool check;
-    Q_UNUSED(check);
 
     if (jid.isEmpty()) {
         warning("Refusing to call an empty jid");
@@ -804,9 +791,8 @@ QXmppCall *QXmppCallManager::call(const QString &jid)
 
     // register call
     d->calls << call;
-    check = connect(call, SIGNAL(destroyed(QObject*)),
-                    this, SLOT(_q_callDestroyed(QObject*)));
-    Q_ASSERT(check);
+    connect(call, &QObject::destroyed,
+                    this, &QXmppCallManager::_q_callDestroyed);
     emit callStarted(call);
 
     call->d->sendInvite();
@@ -888,8 +874,6 @@ void QXmppCallManager::_q_iqReceived(const QXmppIq &ack)
 
 void QXmppCallManager::_q_jingleIqReceived(const QXmppJingleIq &iq)
 {
-    bool check;
-    Q_UNUSED(check);
 
     if (iq.type() != QXmppIq::Set)
         return;
@@ -923,9 +907,8 @@ void QXmppCallManager::_q_jingleIqReceived(const QXmppJingleIq &iq)
 
         // register call
         d->calls << call;
-        check = connect(call, SIGNAL(destroyed(QObject*)),
-                        this, SLOT(_q_callDestroyed(QObject*)));
-        Q_ASSERT(check);
+        connect(call, &QObject::destroyed,
+                        this, &QXmppCallManager::_q_callDestroyed);
 
         // send ringing indication
         QXmppJingleIq ringing;
diff --git a/src/client/QXmppClient.cpp b/src/client/QXmppClient.cpp
index 39f48a0f..523a9e79 100644
--- a/src/client/QXmppClient.cpp
+++ b/src/client/QXmppClient.cpp
@@ -106,54 +106,42 @@ QXmppClient::QXmppClient(QObject *parent)
     : QXmppLoggable(parent),
     d(new QXmppClientPrivate(this))
 {
-    bool check;
-    Q_UNUSED(check);
 
     d->stream = new QXmppOutgoingClient(this);
     d->addProperCapability(d->clientPresence);
 
-    check = connect(d->stream, SIGNAL(elementReceived(QDomElement,bool&)),
-                    this, SLOT(_q_elementReceived(QDomElement,bool&)));
-    Q_ASSERT(check);
+    connect(d->stream, &QXmppOutgoingClient::elementReceived,
+                    this, &QXmppClient::_q_elementReceived);
 
-    check = connect(d->stream, SIGNAL(messageReceived(QXmppMessage)),
-                    this, SIGNAL(messageReceived(QXmppMessage)));
-    Q_ASSERT(check);
+    connect(d->stream, &QXmppOutgoingClient::messageReceived,
+                    this, &QXmppClient::messageReceived);
 
-    check = connect(d->stream, SIGNAL(presenceReceived(QXmppPresence)),
-                    this, SIGNAL(presenceReceived(QXmppPresence)));
-    Q_ASSERT(check);
+    connect(d->stream, &QXmppOutgoingClient::presenceReceived,
+                    this, &QXmppClient::presenceReceived);
 
-    check = connect(d->stream, SIGNAL(iqReceived(QXmppIq)),
-                    this, SIGNAL(iqReceived(QXmppIq)));
-    Q_ASSERT(check);
+    connect(d->stream, &QXmppOutgoingClient::iqReceived,
+                    this, &QXmppClient::iqReceived);
 
-    check = connect(d->stream, SIGNAL(sslErrors(QList<QSslError>)),
-                    this, SIGNAL(sslErrors(QList<QSslError>)));
-    Q_ASSERT(check);
+    connect(d->stream, &QXmppOutgoingClient::sslErrors,
+                    this, &QXmppClient::sslErrors);
 
-    check = connect(d->stream->socket(), SIGNAL(stateChanged(QAbstractSocket::SocketState)),
-                    this, SLOT(_q_socketStateChanged(QAbstractSocket::SocketState)));
-    Q_ASSERT(check);
+    connect(d->stream->socket(), &QAbstractSocket::stateChanged,
+                    this, &QXmppClient::_q_socketStateChanged);
 
-    check = connect(d->stream, SIGNAL(connected()),
-                    this, SLOT(_q_streamConnected()));
-    Q_ASSERT(check);
+    connect(d->stream, &QXmppStream::connected,
+                    this, &QXmppClient::_q_streamConnected);
 
-    check = connect(d->stream, SIGNAL(disconnected()),
-                    this, SLOT(_q_streamDisconnected()));
-    Q_ASSERT(check);
+    connect(d->stream, &QXmppStream::disconnected,
+                    this, &QXmppClient::_q_streamDisconnected);
 
-    check = connect(d->stream, SIGNAL(error(QXmppClient::Error)),
-                    this, SLOT(_q_streamError(QXmppClient::Error)));
-    Q_ASSERT(check);
+    connect(d->stream, &QXmppOutgoingClient::error,
+                    this, &QXmppClient::_q_streamError);
 
     // reconnection
     d->reconnectionTimer = new QTimer(this);
     d->reconnectionTimer->setSingleShot(true);
-    connect(d->reconnectionTimer, SIGNAL(timeout()),
-            this, SLOT(_q_reconnect()));
-    Q_ASSERT(check);
+    connect(d->reconnectionTimer, &QTimer::timeout,
+            this, &QXmppClient::_q_reconnect);
 
     // logging
     setLogger(QXmppLogger::getLogger());
@@ -582,22 +570,22 @@ void QXmppClient::setLogger(QXmppLogger *logger)
 {
     if (logger != d->logger) {
         if (d->logger) {
-            disconnect(this, SIGNAL(logMessage(QXmppLogger::MessageType,QString)),
-                       d->logger, SLOT(log(QXmppLogger::MessageType,QString)));
-            disconnect(this, SIGNAL(setGauge(QString,double)),
-                       d->logger, SLOT(setGauge(QString,double)));
-            disconnect(this, SIGNAL(updateCounter(QString,qint64)),
-                       d->logger, SLOT(updateCounter(QString,qint64)));
+            disconnect(this, &QXmppLoggable::logMessage,
+                       d->logger, &QXmppLogger::log);
+            disconnect(this, &QXmppLoggable::setGauge,
+                       d->logger, &QXmppLogger::setGauge);
+            disconnect(this, &QXmppLoggable::updateCounter,
+                       d->logger, &QXmppLogger::updateCounter);
         }
 
         d->logger = logger;
         if (d->logger) {
-            connect(this, SIGNAL(logMessage(QXmppLogger::MessageType,QString)),
-                    d->logger, SLOT(log(QXmppLogger::MessageType,QString)));
-            connect(this, SIGNAL(setGauge(QString,double)),
-                    d->logger, SLOT(setGauge(QString,double)));
-            connect(this, SIGNAL(updateCounter(QString,qint64)),
-                    d->logger, SLOT(updateCounter(QString,qint64)));
+            connect(this, &QXmppLoggable::logMessage,
+                    d->logger, &QXmppLogger::log);
+            connect(this, &QXmppLoggable::setGauge,
+                    d->logger, &QXmppLogger::setGauge);
+            connect(this, &QXmppLoggable::updateCounter,
+                    d->logger, &QXmppLogger::updateCounter);
         }
 
         emit loggerChanged(d->logger);
diff --git a/src/client/QXmppMucManager.cpp b/src/client/QXmppMucManager.cpp
index 6ddb7851..4c2214ba 100644
--- a/src/client/QXmppMucManager.cpp
+++ b/src/client/QXmppMucManager.cpp
@@ -79,8 +79,8 @@ QXmppMucRoom *QXmppMucManager::addRoom(const QString &roomJid)
     if (!room) {
         room = new QXmppMucRoom(client(), roomJid, this);
         d->rooms.insert(roomJid, room);
-        connect(room, SIGNAL(destroyed(QObject*)),
-            this, SLOT(_q_roomDestroyed(QObject*)));
+        connect(room, &QObject::destroyed,
+            this, &QXmppMucManager::_q_roomDestroyed);
 
         // emit signal
         emit roomAdded(room);
@@ -146,14 +146,11 @@ bool QXmppMucManager::handleStanza(const QDomElement &element)
 
 void QXmppMucManager::setClient(QXmppClient* client)
 {
-    bool check;
-    Q_UNUSED(check);
 
     QXmppClientExtension::setClient(client);
 
-    check = connect(client, SIGNAL(messageReceived(QXmppMessage)),
-                    this, SLOT(_q_messageReceived(QXmppMessage)));
-    Q_ASSERT(check);
+    connect(client, &QXmppClient::messageReceived,
+                    this, &QXmppMucManager::_q_messageReceived);
 }
 /// \endcond
 
@@ -182,8 +179,6 @@ void QXmppMucManager::_q_roomDestroyed(QObject *object)
 QXmppMucRoom::QXmppMucRoom(QXmppClient *client, const QString &jid, QObject *parent)
     : QObject(parent)
 {
-    bool check;
-    Q_UNUSED(check);
 
     d = new QXmppMucRoomPrivate;
     d->allowedActions = NoAction;
@@ -191,30 +186,24 @@ QXmppMucRoom::QXmppMucRoom(QXmppClient *client, const QString &jid, QObject *par
     d->discoManager = client->findExtension<QXmppDiscoveryManager>();
     d->jid = jid;
 
-    check = connect(d->client, SIGNAL(disconnected()),
-                    this, SLOT(_q_disconnected()));
-    Q_ASSERT(check);
+    connect(d->client, &QXmppClient::disconnected,
+                    this, &QXmppMucRoom::_q_disconnected);
 
-    check = connect(d->client, SIGNAL(messageReceived(QXmppMessage)),
-                    this, SLOT(_q_messageReceived(QXmppMessage)));
-    Q_ASSERT(check);
+    connect(d->client, &QXmppClient::messageReceived,
+                    this, &QXmppMucRoom::_q_messageReceived);
 
-    check = connect(d->client, SIGNAL(presenceReceived(QXmppPresence)),
-                    this, SLOT(_q_presenceReceived(QXmppPresence)));
-    Q_ASSERT(check);
+    connect(d->client, &QXmppClient::presenceReceived,
+                    this, &QXmppMucRoom::_q_presenceReceived);
 
     if (d->discoManager) {
-        check = connect(d->discoManager, SIGNAL(infoReceived(QXmppDiscoveryIq)),
-                        this, SLOT(_q_discoveryInfoReceived(QXmppDiscoveryIq)));
-        Q_ASSERT(check);
+        connect(d->discoManager, &QXmppDiscoveryManager::infoReceived,
+                        this, &QXmppMucRoom::_q_discoveryInfoReceived);
     }
 
     // convenience signals for properties
-    check = connect(this, SIGNAL(joined()), this, SIGNAL(isJoinedChanged()));
-    Q_ASSERT(check);
+    connect(this, &QXmppMucRoom::joined, this, &QXmppMucRoom::isJoinedChanged);
 
-    check = connect(this, SIGNAL(left()), this, SIGNAL(isJoinedChanged()));
-    Q_ASSERT(check);
+    connect(this, &QXmppMucRoom::left, this, &QXmppMucRoom::isJoinedChanged);
 }
 
 /// Destroys a QXmppMucRoom.
diff --git a/src/client/QXmppOutgoingClient.cpp b/src/client/QXmppOutgoingClient.cpp
index 764ed25f..1b73542e 100644
--- a/src/client/QXmppOutgoingClient.cpp
+++ b/src/client/QXmppOutgoingClient.cpp
@@ -183,49 +183,27 @@ QXmppOutgoingClient::QXmppOutgoingClient(QObject *parent)
     : QXmppStream(parent),
     d(new QXmppOutgoingClientPrivate(this))
 {
-    bool check;
-    Q_UNUSED(check);
-
     // initialise socket
     auto *socket = new QSslSocket(this);
     setSocket(socket);
 
-    check = connect(socket, SIGNAL(disconnected()),
-                    this, SLOT(_q_socketDisconnected()));
-    Q_ASSERT(check);
-
-    check = connect(socket, SIGNAL(sslErrors(QList<QSslError>)),
-                    this, SLOT(socketSslErrors(QList<QSslError>)));
-    Q_ASSERT(check);
-
-    check = connect(socket, SIGNAL(error(QAbstractSocket::SocketError)),
-                    this, SLOT(socketError(QAbstractSocket::SocketError)));
-    Q_ASSERT(check);
+    connect(socket, &QAbstractSocket::disconnected, this, &QXmppOutgoingClient::_q_socketDisconnected);
+    connect(socket, QOverload<const QList<QSslError> &>::of(&QSslSocket::sslErrors), this, &QXmppOutgoingClient::socketSslErrors);
+    connect(socket, QOverload<QAbstractSocket::SocketError>::of(&QSslSocket::error), this, &QXmppOutgoingClient::socketError);
 
     // DNS lookups
-    check = connect(&d->dns, SIGNAL(finished()),
-                    this, SLOT(_q_dnsLookupFinished()));
-    Q_ASSERT(check);
+    connect(&d->dns, &QDnsLookup::finished, this, &QXmppOutgoingClient::_q_dnsLookupFinished);
 
     // XEP-0199: XMPP Ping
     d->pingTimer = new QTimer(this);
-    check = connect(d->pingTimer, SIGNAL(timeout()),
-                    this, SLOT(pingSend()));
-    Q_ASSERT(check);
+    connect(d->pingTimer, &QTimer::timeout, this, &QXmppOutgoingClient::pingSend);
 
     d->timeoutTimer = new QTimer(this);
     d->timeoutTimer->setSingleShot(true);
-    check = connect(d->timeoutTimer, SIGNAL(timeout()),
-                    this, SLOT(pingTimeout()));
-    Q_ASSERT(check);
-
-    check = connect(this, SIGNAL(connected()),
-                    this, SLOT(pingStart()));
-    Q_ASSERT(check);
+    connect(d->timeoutTimer, &QTimer::timeout, this, &QXmppOutgoingClient::pingTimeout);
 
-    check = connect(this, SIGNAL(disconnected()),
-                    this, SLOT(pingStop()));
-    Q_ASSERT(check);
+    connect(this, &QXmppStream::connected, this, &QXmppOutgoingClient::pingStart);
+    connect(this, &QXmppStream::disconnected, this, &QXmppOutgoingClient::pingStop);
 }
 
 /// Destroys an outgoing client stream.
diff --git a/src/client/QXmppRemoteMethod.cpp b/src/client/QXmppRemoteMethod.cpp
index 2f300cc8..da3b97f6 100644
--- a/src/client/QXmppRemoteMethod.cpp
+++ b/src/client/QXmppRemoteMethod.cpp
@@ -43,8 +43,8 @@ QXmppRemoteMethodResult QXmppRemoteMethod::call( )
     // FIXME : spinning an event loop is a VERY bad idea, it can cause
     // us to lose incoming packets
     QEventLoop loop(this);
-    connect( this, SIGNAL(callDone()), &loop, SLOT(quit()));
-    QTimer::singleShot(30000,&loop, SLOT(quit())); // Timeout in case the other end hangs...
+    connect( this, &QXmppRemoteMethod::callDone, &loop, &QEventLoop::quit);
+    QTimer::singleShot(30000,&loop, &QEventLoop::quit); // Timeout in case the other end hangs...
 
     m_client->sendPacket( m_payload );
 
diff --git a/src/client/QXmppRosterManager.cpp b/src/client/QXmppRosterManager.cpp
index 787815cf..041d1851 100644
--- a/src/client/QXmppRosterManager.cpp
+++ b/src/client/QXmppRosterManager.cpp
@@ -61,22 +61,17 @@ QXmppRosterManagerPrivate::QXmppRosterManagerPrivate(QXmppRosterManager *qq)
 
 QXmppRosterManager::QXmppRosterManager(QXmppClient* client)
 {
-    bool check;
-    Q_UNUSED(check);
 
     d = new QXmppRosterManagerPrivate(this);
 
-    check = connect(client, SIGNAL(connected()),
-                    this, SLOT(_q_connected()));
-    Q_ASSERT(check);
+    connect(client, &QXmppClient::connected,
+                    this, &QXmppRosterManager::_q_connected);
 
-    check = connect(client, SIGNAL(disconnected()),
-                    this, SLOT(_q_disconnected()));
-    Q_ASSERT(check);
+    connect(client, &QXmppClient::disconnected,
+                    this, &QXmppRosterManager::_q_disconnected);
 
-    check = connect(client, SIGNAL(presenceReceived(QXmppPresence)),
-                    this, SLOT(_q_presenceReceived(QXmppPresence)));
-    Q_ASSERT(check);
+    connect(client, &QXmppClient::presenceReceived,
+                    this, &QXmppRosterManager::_q_presenceReceived);
 }
 
 QXmppRosterManager::~QXmppRosterManager()
diff --git a/src/client/QXmppRpcManager.cpp b/src/client/QXmppRpcManager.cpp
index 5cf7737e..0707834a 100644
--- a/src/client/QXmppRpcManager.cpp
+++ b/src/client/QXmppRpcManager.cpp
@@ -128,11 +128,16 @@ QXmppRemoteMethodResult QXmppRpcManager::callRemoteMethod( const QString &jid,
     if( arg9.isValid() ) args << arg9;
     if( arg10.isValid() ) args << arg10;
 
+    bool check;
+    Q_UNUSED(check)
+
     QXmppRemoteMethod method( jid, interface, args, client() );
-    connect(this, SIGNAL(rpcCallResponse(QXmppRpcResponseIq)),
+    check = connect(this, SIGNAL(rpcCallResponse(QXmppRpcResponseIq)),
             &method, SLOT(gotResult(QXmppRpcResponseIq)));
-    connect(this, SIGNAL(rpcCallError(QXmppRpcErrorIq)),
+    Q_ASSERT(check);
+    check = connect(this, SIGNAL(rpcCallError(QXmppRpcErrorIq)),
             &method, SLOT(gotError(QXmppRpcErrorIq)));
+    Q_ASSERT(check);
 
     return method.call();
 }
diff --git a/src/client/QXmppTransferManager.cpp b/src/client/QXmppTransferManager.cpp
index f44d3166..cdcd8689 100644
--- a/src/client/QXmppTransferManager.cpp
+++ b/src/client/QXmppTransferManager.cpp
@@ -28,6 +28,7 @@
 #include <QFileInfo>
 #include <QHash>
 #include <QHostAddress>
+#include <QMetaMethod>
 #include <QNetworkInterface>
 #include <QTime>
 #include <QTimer>
@@ -463,9 +464,6 @@ void QXmppTransferIncomingJob::checkData()
 
 void QXmppTransferIncomingJob::connectToNextHost()
 {
-    bool check;
-    Q_UNUSED(check);
-
     if (m_streamCandidates.isEmpty()) {
         // could not connect to any stream host
         QXmppByteStreamIq response;
@@ -496,17 +494,12 @@ void QXmppTransferIncomingJob::connectToNextHost()
     m_candidateClient = new QXmppSocksClient(m_candidateHost.host(), m_candidateHost.port(), this);
     m_candidateTimer = new QTimer(this);
 
-    check = connect(m_candidateClient, SIGNAL(disconnected()),
-                    this, SLOT(_q_candidateDisconnected()));
-    Q_ASSERT(check);
-
-    check = connect(m_candidateClient, SIGNAL(ready()),
-                    this, SLOT(_q_candidateReady()));
-    Q_ASSERT(check);
-
-    check = connect(m_candidateTimer, SIGNAL(timeout()),
-                    this, SLOT(_q_candidateDisconnected()));
-    Q_ASSERT(check);
+    connect(m_candidateClient, &QAbstractSocket::disconnected,
+            this, &QXmppTransferIncomingJob::_q_candidateDisconnected);
+    connect(m_candidateClient, &QXmppSocksClient::ready,
+            this, &QXmppTransferIncomingJob::_q_candidateReady);
+    connect(m_candidateTimer, &QTimer::timeout,
+            this, &QXmppTransferIncomingJob::_q_candidateDisconnected);
 
     m_candidateTimer->setSingleShot(true);
     m_candidateTimer->start(socksTimeout);
@@ -515,8 +508,6 @@ void QXmppTransferIncomingJob::connectToNextHost()
 
 void QXmppTransferIncomingJob::connectToHosts(const QXmppByteStreamIq &iq)
 {
-    bool check;
-    Q_UNUSED(check);
 
     m_streamCandidates = iq.streamHosts();
     m_streamOfferId = iq.id();
@@ -539,9 +530,6 @@ bool QXmppTransferIncomingJob::writeData(const QByteArray &data)
 
 void QXmppTransferIncomingJob::_q_candidateReady()
 {
-    bool check;
-    Q_UNUSED(check);
-
     if (!m_candidateClient)
         return;
 
@@ -556,13 +544,8 @@ void QXmppTransferIncomingJob::_q_candidateReady()
     m_candidateTimer->deleteLater();
     m_candidateTimer = nullptr;
 
-    check = connect(d->socksSocket, SIGNAL(readyRead()),
-                    this, SLOT(_q_receiveData()));
-    Q_ASSERT(check);
-
-    check = connect(d->socksSocket, SIGNAL(disconnected()),
-                    this, SLOT(_q_disconnected()));
-    Q_ASSERT(check);
+    connect(d->socksSocket, &QIODevice::readyRead, this, &QXmppTransferIncomingJob::_q_receiveData);
+    connect(d->socksSocket, &QAbstractSocket::disconnected, this, &QXmppTransferIncomingJob::_q_disconnected);
 
     QXmppByteStreamIq ackIq;
     ackIq.setId(m_streamOfferId);
@@ -623,9 +606,6 @@ QXmppTransferOutgoingJob::QXmppTransferOutgoingJob(const QString& jid, QXmppClie
 
 void QXmppTransferOutgoingJob::connectToProxy()
 {
-    bool check;
-    Q_UNUSED(check);
-
     info(QString("Connecting to proxy: %1 (%2 %3)").arg(
             d->socksProxy.jid(),
             d->socksProxy.host(),
@@ -637,13 +617,8 @@ void QXmppTransferOutgoingJob::connectToProxy()
 
     QXmppSocksClient *socksClient = new QXmppSocksClient(d->socksProxy.host(), d->socksProxy.port(), this);
 
-    check = connect(socksClient, SIGNAL(disconnected()),
-                    this, SLOT(_q_disconnected()));
-    Q_ASSERT(check);
-
-    check = connect(socksClient, SIGNAL(ready()),
-                    this, SLOT(_q_proxyReady()));
-    Q_ASSERT(check);
+    connect(socksClient, &QAbstractSocket::disconnected, this, &QXmppTransferOutgoingJob::_q_disconnected);
+    connect(socksClient, &QXmppSocksClient::ready, this, &QXmppTransferOutgoingJob::_q_proxyReady);
 
     d->socksSocket = socksClient;
     socksClient->connectToHost(hostName, 0);
@@ -651,18 +626,10 @@ void QXmppTransferOutgoingJob::connectToProxy()
 
 void QXmppTransferOutgoingJob::startSending()
 {
-    bool check;
-    Q_UNUSED(check);
-
     setState(QXmppTransferJob::TransferState);
 
-    check = connect(d->socksSocket, SIGNAL(bytesWritten(qint64)),
-                    this, SLOT(_q_sendData()));
-    Q_ASSERT(check);
-
-    check = connect(d->iodevice, SIGNAL(readyRead()),
-                    this, SLOT(_q_sendData()));
-    Q_ASSERT(check);
+    connect(d->socksSocket, &QIODevice::bytesWritten, this, &QXmppTransferOutgoingJob::_q_sendData);
+    connect(d->iodevice, &QIODevice::readyRead, this, &QXmppTransferOutgoingJob::_q_sendData);
 
     _q_sendData();
 }
@@ -793,16 +760,12 @@ QXmppTransferOutgoingJob *QXmppTransferManagerPrivate::getOutgoingJobByRequestId
 
 QXmppTransferManager::QXmppTransferManager()
 {
-    bool check;
-    Q_UNUSED(check);
-
     d = new QXmppTransferManagerPrivate(this);
 
     // start SOCKS server
     d->socksServer = new QXmppSocksServer(this);
-    check = connect(d->socksServer, SIGNAL(newConnection(QTcpSocket*,QString,quint16)),
-                    this, SLOT(_q_socksServerConnected(QTcpSocket*,QString,quint16)));
-    Q_ASSERT(check);
+    connect(d->socksServer, &QXmppSocksServer::newConnection, this, &QXmppTransferManager::_q_socksServerConnected);
+
     if (!d->socksServer->listen()) {
         qWarning("QXmppSocksServer could not start listening");
     }
@@ -850,9 +813,6 @@ void QXmppTransferManager::byteStreamResponseReceived(const QXmppIq &iq)
 /// a stream host.
 void QXmppTransferManager::byteStreamResultReceived(const QXmppByteStreamIq &iq)
 {
-    bool check;
-    Q_UNUSED(check);
-
     QXmppTransferOutgoingJob *job = d->getOutgoingJobByRequestId(iq.from(), iq.id());
     if (!job ||
         job->method() != QXmppTransferJob::SocksMethod ||
@@ -873,10 +833,8 @@ void QXmppTransferManager::byteStreamResultReceived(const QXmppByteStreamIq &iq)
         job->terminate(QXmppTransferJob::ProtocolError);
         return;
     }
-    check = connect(job->d->socksSocket, SIGNAL(disconnected()),
-                    job, SLOT(_q_disconnected()));
-    Q_ASSERT(check);
-
+    
+    connect(job->d->socksSocket, &QTcpSocket::disconnected, job, &QXmppTransferOutgoingJob::_q_disconnected);
     job->startSending();
 }
 
@@ -884,8 +842,6 @@ void QXmppTransferManager::byteStreamResultReceived(const QXmppByteStreamIq &iq)
 /// to a stream host.
 void QXmppTransferManager::byteStreamSetReceived(const QXmppByteStreamIq &iq)
 {
-    bool check;
-    Q_UNUSED(check);
 
     QXmppIq response;
     response.setId(iq.id());
@@ -967,15 +923,10 @@ bool QXmppTransferManager::handleStanza(const QDomElement &element)
 
 void QXmppTransferManager::setClient(QXmppClient *client)
 {
-    bool check;
-    Q_UNUSED(check);
-
     QXmppClientExtension::setClient(client);
 
     // XEP-0047: In-Band Bytestreams
-    check = connect(client, SIGNAL(iqReceived(QXmppIq)),
-                    this, SLOT(_q_iqReceived(QXmppIq)));
-    Q_ASSERT(check);
+    connect(client, &QXmppClient::iqReceived, this, &QXmppTransferManager::_q_iqReceived);
 }
 /// \endcond
 
@@ -1134,8 +1085,6 @@ void QXmppTransferManager::ibbResponseReceived(const QXmppIq &iq)
 
 void QXmppTransferManager::_q_iqReceived(const QXmppIq &iq)
 {
-    bool check;
-    Q_UNUSED(check);
 
     for (auto *ptr : d->jobs) {
         // handle IQ from proxy
@@ -1222,9 +1171,6 @@ void QXmppTransferManager::_q_jobFinished()
 
 void QXmppTransferManager::_q_jobStateChanged(QXmppTransferJob::State state)
 {
-    bool check;
-    Q_UNUSED(check);
-
     auto *job = qobject_cast<QXmppTransferJob *>(sender());
     if (!job || !d->jobs.contains(job))
         return;
@@ -1233,8 +1179,8 @@ void QXmppTransferManager::_q_jobStateChanged(QXmppTransferJob::State state)
         return;
 
     // disconnect from the signal
-    disconnect(job, SIGNAL(stateChanged(QXmppTransferJob::State)),
-               this, SLOT(_q_jobStateChanged(QXmppTransferJob::State)));
+    disconnect(job, &QXmppTransferJob::stateChanged,
+               this, &QXmppTransferManager::_q_jobStateChanged);
 
     // the job was refused by the local party
     if (state != QXmppTransferJob::StartState || !job->d->iodevice || !job->d->iodevice->isWritable())
@@ -1254,9 +1200,7 @@ void QXmppTransferManager::_q_jobStateChanged(QXmppTransferJob::State state)
     }
 
     // the job was accepted by the local party
-    check = connect(job, SIGNAL(error(QXmppTransferJob::Error)),
-            this, SLOT(_q_jobError(QXmppTransferJob::Error)));
-    Q_ASSERT(check);
+    connect(job, QOverload<QXmppTransferJob::Error>::of(&QXmppTransferJob::error), this, &QXmppTransferManager::_q_jobError);
 
     QXmppDataForm form;
     form.setType(QXmppDataForm::Submit);
@@ -1348,9 +1292,6 @@ QXmppTransferJob *QXmppTransferManager::sendFile(const QString &jid, const QStri
 
 QXmppTransferJob *QXmppTransferManager::sendFile(const QString &jid, QIODevice *device, const QXmppTransferFileInfo &fileInfo, const QString &sid)
 {
-    bool check;
-    Q_UNUSED(check);
-
     if (QXmppUtils::jidToResource(jid).isEmpty()) {
         warning("The file recipient's JID must be a full JID");
         return nullptr;
@@ -1392,17 +1333,10 @@ QXmppTransferJob *QXmppTransferManager::sendFile(const QString &jid, QIODevice *
 
     // start job
     d->jobs.append(job);
-    check = connect(job, SIGNAL(destroyed(QObject*)),
-                    this, SLOT(_q_jobDestroyed(QObject*)));
-    Q_ASSERT(check);
-
-    check = connect(job, SIGNAL(error(QXmppTransferJob::Error)),
-                    this, SLOT(_q_jobError(QXmppTransferJob::Error)));
-    Q_ASSERT(check);
 
-    check = connect(job, SIGNAL(finished()),
-                    this, SLOT(_q_jobFinished()));
-    Q_ASSERT(check);
+    connect(job, &QObject::destroyed, this, &QXmppTransferManager::_q_jobDestroyed);    
+    connect(job, QOverload<QXmppTransferJob::Error>::of(&QXmppTransferJob::error), this, &QXmppTransferManager::_q_jobError);
+    connect(job, &QXmppTransferJob::finished, this, &QXmppTransferManager::_q_jobFinished);
 
     QXmppStreamInitiationIq request;
     request.setType(QXmppIq::Set);
@@ -1536,9 +1470,6 @@ void QXmppTransferManager::streamInitiationResultReceived(const QXmppStreamIniti
 
 void QXmppTransferManager::streamInitiationSetReceived(const QXmppStreamInitiationIq &iq)
 {
-    bool check;
-    Q_UNUSED(check);
-
     QXmppIq response;
     response.setTo(iq.from());
     response.setId(iq.id());
@@ -1558,8 +1489,7 @@ void QXmppTransferManager::streamInitiationSetReceived(const QXmppStreamInitiati
     }
 
     // check there is a receiver connected to the fileReceived() signal
-    if (!receivers(SIGNAL(fileReceived(QXmppTransferJob*))))
-    {
+    if (!isSignalConnected(QMetaMethod::fromSignal(&QXmppTransferManager::fileReceived))) {
         QXmppStanza::Error error(QXmppStanza::Error::Cancel, QXmppStanza::Error::Forbidden);
         error.setCode(403);
 
@@ -1613,17 +1543,10 @@ void QXmppTransferManager::streamInitiationSetReceived(const QXmppStreamInitiati
 
     // register job
     d->jobs.append(job);
-    check = connect(job, SIGNAL(destroyed(QObject*)),
-                    this, SLOT(_q_jobDestroyed(QObject*)));
-    Q_ASSERT(check);
-
-    check = connect(job, SIGNAL(finished()),
-                    this, SLOT(_q_jobFinished()));
-    Q_ASSERT(check);
 
-    check = connect(job, SIGNAL(stateChanged(QXmppTransferJob::State)),
-                    this, SLOT(_q_jobStateChanged(QXmppTransferJob::State)));
-    Q_ASSERT(check);
+    connect(job, &QObject::destroyed, this, &QXmppTransferManager::_q_jobDestroyed);
+    connect(job, &QXmppTransferJob::finished, this, &QXmppTransferManager::_q_jobFinished);
+    connect(job, &QXmppTransferJob::stateChanged, this, &QXmppTransferManager::_q_jobStateChanged);
 
     // allow user to accept or decline the job
     emit fileReceived(job);
diff --git a/src/client/QXmppTransferManager_p.h b/src/client/QXmppTransferManager_p.h
index 8bc007fd..cf44f4d3 100644
--- a/src/client/QXmppTransferManager_p.h
+++ b/src/client/QXmppTransferManager_p.h
@@ -77,8 +77,10 @@ public:
     void connectToProxy();
     void startSending();
 
-private slots:
+public slots:
     void _q_disconnected();
+
+private slots:
     void _q_proxyReady();
     void _q_sendData();
 };
diff --git a/src/server/QXmppIncomingClient.cpp b/src/server/QXmppIncomingClient.cpp
index d3cd5cd9..c7da7bfd 100644
--- a/src/server/QXmppIncomingClient.cpp
+++ b/src/server/QXmppIncomingClient.cpp
@@ -77,14 +77,14 @@ void QXmppIncomingClientPrivate::checkCredentials(const QByteArray &response)
         QXmppPasswordReply *reply = passwordChecker->checkPassword(request);
         reply->setParent(q);
         reply->setProperty("__sasl_raw", response);
-        QObject::connect(reply, SIGNAL(finished()),
-                         q, SLOT(onPasswordReply()));
+        QObject::connect(reply, &QXmppPasswordReply::finished,
+                         q, &QXmppIncomingClient::onPasswordReply);
     } else if (saslServer->mechanism() == "DIGEST-MD5") {
         QXmppPasswordReply *reply = passwordChecker->getDigest(request);
         reply->setParent(q);
         reply->setProperty("__sasl_raw", response);
-        QObject::connect(reply, SIGNAL(finished()),
-                         q, SLOT(onDigestReply()));
+        QObject::connect(reply, &QXmppPasswordReply::finished,
+                         q, &QXmppIncomingClient::onDigestReply);
     }
 }
 
@@ -107,16 +107,13 @@ QString QXmppIncomingClientPrivate::origin() const
 QXmppIncomingClient::QXmppIncomingClient(QSslSocket *socket, const QString &domain, QObject *parent)
     : QXmppStream(parent)
 {
-    bool check;
-    Q_UNUSED(check);
 
     d = new QXmppIncomingClientPrivate(this);
     d->domain = domain;
 
     if (socket) {
-        check = connect(socket, SIGNAL(disconnected()),
-                        this, SLOT(onSocketDisconnected()));
-        Q_ASSERT(check);
+        connect(socket, &QAbstractSocket::disconnected,
+                        this, &QXmppIncomingClient::onSocketDisconnected);
 
         setSocket(socket);
     }
@@ -126,9 +123,8 @@ QXmppIncomingClient::QXmppIncomingClient(QSslSocket *socket, const QString &doma
     // create inactivity timer
     d->idleTimer = new QTimer(this);
     d->idleTimer->setSingleShot(true);
-    check = connect(d->idleTimer, SIGNAL(timeout()),
-                    this, SLOT(onTimeout()));
-    Q_ASSERT(check);
+    connect(d->idleTimer, &QTimer::timeout,
+                    this, &QXmppIncomingClient::onTimeout);
 }
 
 /// Destroys the current stream.
@@ -465,7 +461,7 @@ void QXmppIncomingClient::onTimeout()
     disconnectFromHost();
 
     // make sure disconnected() gets emitted no matter what
-    QTimer::singleShot(30, this, SIGNAL(disconnected()));
+    QTimer::singleShot(30, this, &QXmppStream::disconnected);
 }
 
 
diff --git a/src/server/QXmppIncomingServer.cpp b/src/server/QXmppIncomingServer.cpp
index 1963221b..f121e479 100644
--- a/src/server/QXmppIncomingServer.cpp
+++ b/src/server/QXmppIncomingServer.cpp
@@ -71,16 +71,13 @@ QString QXmppIncomingServerPrivate::origin() const
 QXmppIncomingServer::QXmppIncomingServer(QSslSocket *socket, const QString &domain, QObject *parent)
     : QXmppStream(parent)
 {
-    bool check;
-    Q_UNUSED(check);
 
     d = new QXmppIncomingServerPrivate(this);
     d->domain = domain;
 
     if (socket) {
-        check = connect(socket, SIGNAL(disconnected()),
-                        this, SLOT(slotSocketDisconnected()));
-        Q_ASSERT(check);
+        connect(socket, &QAbstractSocket::disconnected,
+                        this, &QXmppIncomingServer::slotSocketDisconnected);
 
         setSocket(socket);
     }
@@ -160,10 +157,8 @@ void QXmppIncomingServer::handleStanza(const QDomElement &stanza)
 
             // establish dialback connection
             auto *stream = new QXmppOutgoingServer(d->domain, this);
-            bool check = connect(stream, SIGNAL(dialbackResponseReceived(QXmppDialback)),
-                                 this, SLOT(slotDialbackResponseReceived(QXmppDialback)));
-            Q_ASSERT(check);
-            Q_UNUSED(check);
+            connect(stream, &QXmppOutgoingServer::dialbackResponseReceived,
+                                 this, &QXmppIncomingServer::slotDialbackResponseReceived);
             stream->setVerify(d->localStreamId, request.key());
             stream->connectToHost(domain);
         }
diff --git a/src/server/QXmppOutgoingServer.cpp b/src/server/QXmppOutgoingServer.cpp
index 4e2e274c..aec5018a 100644
--- a/src/server/QXmppOutgoingServer.cpp
+++ b/src/server/QXmppOutgoingServer.cpp
@@ -22,8 +22,10 @@
  */
 
 #include <QDomElement>
+#include <QSslError>
 #include <QSslKey>
 #include <QSslSocket>
+#include <QList>
 #include <QTimer>
 #include <QDnsLookup>
 
@@ -57,39 +59,25 @@ QXmppOutgoingServer::QXmppOutgoingServer(const QString &domain, QObject *parent)
     : QXmppStream(parent),
     d(new QXmppOutgoingServerPrivate)
 {
-    bool check;
-    Q_UNUSED(check);
-
     // socket initialisation
     auto *socket = new QSslSocket(this);
     setSocket(socket);
 
-    check = connect(socket, SIGNAL(disconnected()),
-                    this, SLOT(_q_socketDisconnected()));
-    Q_ASSERT(check);
-
-    check = connect(socket, SIGNAL(error(QAbstractSocket::SocketError)),
-                    this, SLOT(socketError(QAbstractSocket::SocketError)));
-    Q_ASSERT(check);
+    connect(socket, &QAbstractSocket::disconnected, this, &QXmppOutgoingServer::_q_socketDisconnected);
+    connect(socket, QOverload<QAbstractSocket::SocketError>::of(&QSslSocket::error), this, &QXmppOutgoingServer::socketError);
 
     // DNS lookups
-    check = connect(&d->dns, SIGNAL(finished()),
-                    this, SLOT(_q_dnsLookupFinished()));
-    Q_ASSERT(check);
+    connect(&d->dns, &QDnsLookup::finished, this, &QXmppOutgoingServer::_q_dnsLookupFinished);
 
     d->dialbackTimer = new QTimer(this);
     d->dialbackTimer->setInterval(5000);
     d->dialbackTimer->setSingleShot(true);
-    check = connect(d->dialbackTimer, SIGNAL(timeout()),
-                    this, SLOT(sendDialback()));
-    Q_ASSERT(check);
+    connect(d->dialbackTimer, &QTimer::timeout, this, &QXmppOutgoingServer::sendDialback);
 
     d->localDomain = domain;
     d->ready = false;
 
-    check = connect(socket, SIGNAL(sslErrors(QList<QSslError>)),
-                    this, SLOT(slotSslErrors(QList<QSslError>)));
-    Q_ASSERT(check);
+    connect(socket, QOverload<const QList<QSslError> &>::of(&QSslSocket::sslErrors), this, &QXmppOutgoingServer::slotSslErrors);
 }
 
 /// Destroys the stream.
diff --git a/src/server/QXmppPasswordChecker.cpp b/src/server/QXmppPasswordChecker.cpp
index 45ce4604..70bfad83 100644
--- a/src/server/QXmppPasswordChecker.cpp
+++ b/src/server/QXmppPasswordChecker.cpp
@@ -128,7 +128,7 @@ void QXmppPasswordReply::finish()
 
 void QXmppPasswordReply::finishLater()
 {
-    QTimer::singleShot(0, this, SLOT(finish()));
+    QTimer::singleShot(0, this, &QXmppPasswordReply::finish);
 }
 
 /// Returns true when the reply has finished.
diff --git a/src/server/QXmppServer.cpp b/src/server/QXmppServer.cpp
index 71a55181..2cf25362 100644
--- a/src/server/QXmppServer.cpp
+++ b/src/server/QXmppServer.cpp
@@ -152,8 +152,6 @@ bool QXmppServerPrivate::routeData(const QString &to, const QByteArray &data)
 
     } else if (!serversForServers.isEmpty()) {
 
-        bool check;
-        Q_UNUSED(check);
 
         // look for an outgoing S2S connection
         for (auto *conn : qAsConst(outgoingServers)) {
@@ -171,9 +169,8 @@ bool QXmppServerPrivate::routeData(const QString &to, const QByteArray &data)
         conn->moveToThread(q->thread());
         conn->setParent(q);
 
-        check = QObject::connect(conn, SIGNAL(disconnected()),
-                                 q, SLOT(_q_outgoingServerDisconnected()));
-        Q_UNUSED(check);
+        QObject::connect(conn, &QXmppStream::disconnected,
+                                 q, &QXmppServer::_q_outgoingServerDisconnected);
 
         // add stream
         outgoingServers.insert(conn);
@@ -387,22 +384,22 @@ void QXmppServer::setLogger(QXmppLogger *logger)
 {
     if (logger != d->logger) {
         if (d->logger) {
-            disconnect(this, SIGNAL(logMessage(QXmppLogger::MessageType,QString)),
-                       d->logger, SLOT(log(QXmppLogger::MessageType,QString)));
-            disconnect(this, SIGNAL(setGauge(QString,double)),
-                       d->logger, SLOT(setGauge(QString,double)));
-            disconnect(this, SIGNAL(updateCounter(QString,qint64)),
-                       d->logger, SLOT(updateCounter(QString,qint64)));
+            disconnect(this, &QXmppLoggable::logMessage,
+                       d->logger, &QXmppLogger::log);
+            disconnect(this, &QXmppLoggable::setGauge,
+                       d->logger, &QXmppLogger::setGauge);
+            disconnect(this, &QXmppLoggable::updateCounter,
+                       d->logger, &QXmppLogger::updateCounter);
         }
 
         d->logger = logger;
         if (d->logger) {
-            connect(this, SIGNAL(logMessage(QXmppLogger::MessageType,QString)),
-                    d->logger, SLOT(log(QXmppLogger::MessageType,QString)));
-            connect(this, SIGNAL(setGauge(QString,double)),
-                    d->logger, SLOT(setGauge(QString,double)));
-            connect(this, SIGNAL(updateCounter(QString,qint64)),
-                    d->logger, SLOT(updateCounter(QString,qint64)));
+            connect(this, &QXmppLoggable::logMessage,
+                    d->logger, &QXmppLogger::log);
+            connect(this, &QXmppLoggable::setGauge,
+                    d->logger, &QXmppLogger::setGauge);
+            connect(this, &QXmppLoggable::updateCounter,
+                    d->logger, &QXmppLogger::updateCounter);
         }
 
         emit loggerChanged(d->logger);
@@ -540,7 +537,7 @@ void QXmppServer::setPrivateKey(const QSslKey &key)
 bool QXmppServer::listenForClients(const QHostAddress &address, quint16 port)
 {
     bool check;
-    Q_UNUSED(check);
+    Q_UNUSED(check)
 
     if (d->domain.isEmpty()) {
         d->warning("No domain was specified!");
@@ -604,7 +601,7 @@ void QXmppServer::close()
 bool QXmppServer::listenForServers(const QHostAddress &address, quint16 port)
 {
     bool check;
-    Q_UNUSED(check);
+    Q_UNUSED(check)
 
     if (d->domain.isEmpty()) {
         d->warning("No domain was specified!");
@@ -672,22 +669,17 @@ bool QXmppServer::sendPacket(const QXmppStanza &packet)
 
 void QXmppServer::addIncomingClient(QXmppIncomingClient *stream)
 {
-    bool check;
-    Q_UNUSED(check);
 
     stream->setPasswordChecker(d->passwordChecker);
 
-    check = connect(stream, SIGNAL(connected()),
-                    this, SLOT(_q_clientConnected()));
-    Q_ASSERT(check);
+    connect(stream, &QXmppStream::connected,
+                    this, &QXmppServer::_q_clientConnected);
 
-    check = connect(stream, SIGNAL(disconnected()),
-                    this, SLOT(_q_clientDisconnected()));
-    Q_ASSERT(check);
+    connect(stream, &QXmppStream::disconnected,
+                    this, &QXmppServer::_q_clientDisconnected);
 
-    check = connect(stream, SIGNAL(elementReceived(QDomElement)),
-                    this, SLOT(handleElement(QDomElement)));
-    Q_ASSERT(check);
+    connect(stream, &QXmppIncomingClient::elementReceived,
+                    this, &QXmppServer::handleElement);
 
     // add stream
     d->incomingClients.insert(stream);
@@ -824,8 +816,6 @@ void QXmppServer::_q_outgoingServerDisconnected()
 
 void QXmppServer::_q_serverConnection(QSslSocket *socket)
 {
-    bool check;
-    Q_UNUSED(check);
 
     // check the socket didn't die since the signal was emitted
     if (socket->state() != QAbstractSocket::ConnectedState) {
@@ -836,17 +826,14 @@ void QXmppServer::_q_serverConnection(QSslSocket *socket)
     auto *stream = new QXmppIncomingServer(socket, d->domain, this);
     socket->setParent(stream);
 
-    check = connect(stream, SIGNAL(disconnected()),
-                    this, SLOT(_q_serverDisconnected()));
-    Q_ASSERT(check);
+    connect(stream, &QXmppStream::disconnected,
+                    this, &QXmppServer::_q_serverDisconnected);
 
-    check = connect(stream, SIGNAL(dialbackRequestReceived(QXmppDialback)),
-                    this, SLOT(_q_dialbackRequestReceived(QXmppDialback)));
-    Q_ASSERT(check);
+    connect(stream, &QXmppIncomingServer::dialbackRequestReceived,
+                    this, &QXmppServer::_q_dialbackRequestReceived);
 
-    check = connect(stream, SIGNAL(elementReceived(QDomElement)),
-                    this, SLOT(handleElement(QDomElement)));
-    Q_ASSERT(check);
+    connect(stream, &QXmppIncomingServer::elementReceived,
+                    this, &QXmppServer::handleElement);
 
     // add stream
     d->incomingServers.insert(stream);