Simplify and optimize some string usages

- Using QLatin1String when concatinating strings is faster, because they
  are more lightweight. For the resulting string, we need to allocate
  new memory anyway
- Use QLatin1String overloads where they are provided by Qt APIs
- Just use const char* for log messages, the quoting of QStrings is not
  needed
- Make sure to reuse string results when possible

core/backends/lan/lanlinkprovider.cpp

@@ -104,7 +104,7 @@ void LanLinkProvider::onStart()
         QAbstractSocket::SocketError sockErr = m_udpSocket.error();
         // Refer to https://doc.qt.io/qt-5/qabstractsocket.html#SocketError-enum to decode socket error number
         QString errorMessage = QString::fromLatin1(QMetaEnum::fromType<QAbstractSocket::SocketError>().valueToKey(sockErr));
-        qCritical(KDECONNECT_CORE) << QLatin1String("Failed to bind UDP socket on port") << m_udpListenPort << QLatin1String("with error") << errorMessage;
+        qCritical(KDECONNECT_CORE) << "Failed to bind UDP socket on port" << m_udpListenPort << "with error" << errorMessage;
     }
     Q_ASSERT(success);
 

core/dbushelper.cpp

@@ -84,8 +84,8 @@ void DBusInstancePrivate::launchDBusDaemon()
         kdeconnectDBusConfiguration = QStandardPaths::locate(QStandardPaths::AppDataLocation, QStringLiteral("dbus-1/session.conf"));
     } else {
         // macOS Debug env
-        dbusDaemonExecutable = QString::fromLatin1(qgetenv("craftRoot")) + QStringLiteral("/../bin/dbus-daemon");
+        dbusDaemonExecutable = QLatin1String(qgetenv("craftRoot")) + QLatin1String("/../bin/dbus-daemon");
-        kdeconnectDBusConfiguration = QString::fromLatin1(qgetenv("craftRoot")) + QStringLiteral("/../share/dbus-1/session.conf");
+        kdeconnectDBusConfiguration = QLatin1String(qgetenv("craftRoot")) + QLatin1String("/../share/dbus-1/session.conf");
     }
     m_dbusProcess->setProgram(dbusDaemonExecutable);
     m_dbusProcess->setArguments({QStringLiteral("--print-address"),

core/device.cpp

@@ -446,13 +446,13 @@ QString Device::encryptionInfo() const
 
     QString localChecksum = QString::fromLatin1(KdeConnectConfig::instance().certificate().digest(digestAlgorithm).toHex());
     for (int i = 2; i < localChecksum.size(); i += 3) {
-        localChecksum.insert(i, QStringLiteral(":")); // Improve readability
+        localChecksum.insert(i, QLatin1Char(':')); // Improve readability
     }
     result += i18n("SHA256 fingerprint of your device certificate is: %1\n", localChecksum);
 
     QString remoteChecksum = QString::fromLatin1(certificate().digest(digestAlgorithm).toHex());
     for (int i = 2; i < remoteChecksum.size(); i += 3) {
-        remoteChecksum.insert(i, QStringLiteral(":")); // Improve readability
+        remoteChecksum.insert(i, QLatin1Char(':')); // Improve readability
     }
     result += i18n("SHA256 fingerprint of remote device certificate is: %1\n", remoteChecksum);
 

indicator/indicatorhelper_mac.cpp

@@ -127,10 +127,10 @@ int IndicatorHelper::daemonHook(QProcess &kdeconnectd)
     }
 
     // Start kdeconnectd, the daemon will not duplicate when there is already one
-    if (QFile::exists(QCoreApplication::applicationDirPath() + QStringLiteral("/kdeconnectd"))) {
+    if (QString daemon = QCoreApplication::applicationDirPath() + QLatin1String("/kdeconnectd"); QFile::exists(daemon)) {
-        kdeconnectd.setProgram(QCoreApplication::applicationDirPath() + QStringLiteral("/kdeconnectd"));
+        kdeconnectd.setProgram(daemon);
-    } else if (QFile::exists(QString::fromLatin1(qgetenv("craftRoot")) + QStringLiteral("/../lib/libexec/kdeconnectd"))) {
+    } else if (QString daemon = QLatin1String(qgetenv("craftRoot")) + QLatin1String("/../lib/libexec/kdeconnectd"); QFile::exists(daemon)) {
-        kdeconnectd.setProgram(QString::fromLatin1(qgetenv("craftRoot")) + QStringLiteral("/../lib/libexec/kdeconnectd"));
+        kdeconnectd.setProgram(daemon);
     } else {
         QMessageBox::critical(nullptr, i18n("KDE Connect"), i18n("Cannot find kdeconnectd"), QMessageBox::Abort, QMessageBox::Abort);
         return -1;

plugins/contacts/contactsplugin.h

@@ -59,11 +59,9 @@ class QObject;
  */
 
 #ifdef Q_OS_WIN
-Q_GLOBAL_STATIC_WITH_ARGS(QString, vcardsLocation, (QStandardPaths::writableLocation(QStandardPaths::HomeLocation) + QString::fromLatin1("/Contacts")))
+Q_GLOBAL_STATIC_WITH_ARGS(QString, vcardsLocation, (QStandardPaths::writableLocation(QStandardPaths::HomeLocation) + QLatin1String("/Contacts")))
 #else
-Q_GLOBAL_STATIC_WITH_ARGS(QString,
+Q_GLOBAL_STATIC_WITH_ARGS(QString, vcardsLocation, (QStandardPaths::writableLocation(QStandardPaths::GenericDataLocation) + QLatin1String("/kpeoplevcard")))
-                          vcardsLocation,
-                          (QStandardPaths::writableLocation(QStandardPaths::GenericDataLocation) + QString::fromLatin1("/kpeoplevcard")))
 #endif
 
 #define VCARD_EXTENSION QStringLiteral(".vcf")

plugins/findmyphone/findmyphoneplugin.cpp

@@ -27,7 +27,7 @@ void FindMyPhonePlugin::ring()
 
 QString FindMyPhonePlugin::dbusPath() const
 {
-    return QString::fromLatin1("/modules/kdeconnect/devices/") + device()->id() + QString::fromLatin1("/findmyphone");
+    return QLatin1String("/modules/kdeconnect/devices/") + device()->id() + QLatin1String("/findmyphone");
 }
 
 #include "findmyphoneplugin.moc"