Fix various clazy warnings

src/core/database.cpp

@@ -184,7 +184,8 @@ QSqlDatabase Database::Connect() {
   }
 
   // Attach external databases
-  for (const QString &key : attached_databases_.keys()) {
+  QStringList keys = attached_databases_.keys();
+  for (const QString &key : keys) {
     QString filename = attached_databases_[key].filename_;
 
     if (!injected_database_name_.isNull()) filename = injected_database_name_;
@@ -204,7 +205,8 @@ QSqlDatabase Database::Connect() {
   }
 
   // We might have to initialize the schema in some attached databases now, if they were deleted and don't match up with the main schema version.
-  for (const QString &key : attached_databases_.keys()) {
+  keys = attached_databases_.keys();
+  for (const QString &key : keys) {
     if (attached_databases_[key].is_temporary_ && attached_databases_[key].schema_.isEmpty())
       continue;
     // Find out if there are any tables in this database
@@ -453,7 +455,8 @@ QStringList Database::SongsTables(QSqlDatabase &db, int schema_version) const {
   }
 
   // look for the tables in attached dbs
-  for (const QString &key : attached_databases_.keys()) {
+  QStringList keys = attached_databases_.keys();
+  for (const QString &key : keys) {
     QSqlQuery q(db);
     q.prepare(QString("SELECT NAME FROM %1.sqlite_master WHERE type='table' AND name='songs' OR name LIKE '%songs'").arg(key));
     if (q.exec()) {

src/core/iconloader.cpp

@@ -75,7 +75,7 @@ QIcon IconLoader::Load(const QString &name, const int fixed_size, const int min_
     if (icon_prop.allow_system_icon) {
       ret = QIcon::fromTheme(name);
       if (ret.isNull()) {
-        for (QString alt_name : icon_prop.names) {
+        for (const QString &alt_name : icon_prop.names) {
           ret = QIcon::fromTheme(alt_name);
           if (!ret.isNull()) break;
         }

src/core/mainwindow.cpp

@@ -1913,7 +1913,7 @@ void MainWindow::PlaylistRightClick(const QPoint &global_pos, const QModelIndex
     QString column_value = app_->playlist_manager()->current()->data(source_index).toString();
     if (column_value.length() > 25) column_value = column_value.left(25) + "...";
 
-    ui_->action_selection_set_value->setText(tr("Set %1 to \"%2\"...").arg(column_name.toLower()).arg(column_value));
+    ui_->action_selection_set_value->setText(tr("Set %1 to \"%2\"...").arg(column_name.toLower(), column_value));
     ui_->action_edit_value->setText(tr("Edit tag \"%1\"...").arg(column_name));
 
     // Is it a collection item?

src/core/mergedproxymodel.cpp

@@ -418,7 +418,8 @@ QStringList MergedProxyModel::mimeTypes() const {
   QStringList ret;
   ret << sourceModel()->mimeTypes();
 
-  for (const QAbstractItemModel *model : merge_points_.keys()) {
+  QList<QAbstractItemModel*> models = merge_points_.keys();
+  for (const QAbstractItemModel *model : models) {
     ret << model->mimeTypes();
   }
 
@@ -495,7 +496,8 @@ QAbstractItemModel *MergedProxyModel::GetModel(const QModelIndex &source_index)
   // This is essentially const_cast<QAbstractItemModel*>(source_index.model()), but without the const_cast
   const QAbstractItemModel *const_model = source_index.model();
   if (const_model == sourceModel()) return sourceModel();
-  for (QAbstractItemModel *submodel : merge_points_.keys()) {
+  QList<QAbstractItemModel*> submodels = merge_points_.keys();
+  for (QAbstractItemModel *submodel : submodels) {
     if (submodel == const_model) return submodel;
   }
   return nullptr;
@@ -509,19 +511,21 @@ void MergedProxyModel::DataChanged(const QModelIndex &top_left, const QModelInde
 void MergedProxyModel::LayoutAboutToBeChanged() {
 
   old_merge_points_.clear();
-  for (QAbstractItemModel *key : merge_points_.keys()) {
-    old_merge_points_[key] = merge_points_.value(key);
+  QList<QAbstractItemModel*> models = merge_points_.keys();
+  for (QAbstractItemModel *model : models) {
+    old_merge_points_[model] = merge_points_.value(model);
   }
 
 }
 
 void MergedProxyModel::LayoutChanged() {
 
-  for (QAbstractItemModel *key : merge_points_.keys()) {
-    if (!old_merge_points_.contains(key)) continue;
+  QList<QAbstractItemModel*> models = merge_points_.keys();
+  for (QAbstractItemModel *model : models) {
+    if (!old_merge_points_.contains(model)) continue;
 
-    const int old_row = old_merge_points_[key].row();
-    const int new_row = merge_points_[key].row();
+    const int old_row = old_merge_points_[model].row();
+    const int new_row = merge_points_[model].row();
 
     if (old_row != new_row) {
       beginResetModel();

src/core/qtsystemtrayicon.cpp

@@ -61,7 +61,7 @@ QtSystemTrayIcon::QtSystemTrayIcon(QObject *parent)
   }
   tray_->setIcon(normal_icon_);
   tray_->installEventFilter(this);
-  ClearNowPlaying();
+  QtSystemTrayIcon::ClearNowPlaying();
 
   QObject::connect(tray_, &QSystemTrayIcon::activated, this, &QtSystemTrayIcon::Clicked);
 

src/core/song.cpp

@@ -1038,7 +1038,6 @@ void Song::InitFromFilePartial(const QString &filename) {
   set_url(QUrl::fromLocalFile(filename));
   QFileInfo info(filename);
   d->basefilename_ = info.fileName();
-  QString suffix = info.suffix().toLower();
 
   TagLib::FileRef fileref(filename.toUtf8().constData());
   if (fileref.file()) {
@@ -1458,7 +1457,7 @@ QString Song::TitleWithCompilationArtist() const {
 
   if (title.isEmpty()) title = d->basefilename_;
 
-  if (is_compilation() && !d->artist_.isEmpty() && !d->artist_.toLower().contains("various")) title = d->artist_ + " - " + title;
+  if (is_compilation() && !d->artist_.isEmpty() && !d->artist_.contains("various", Qt::CaseInsensitive)) title = d->artist_ + " - " + title;
 
   return title;
 

src/core/taskmanager.cpp

@@ -116,7 +116,8 @@ void TaskManager::SetTaskFinished(const int id) {
 
     if (tasks_[id].blocks_collection_scans) {
       resume_collection_watchers = true;
-      for (const Task &task : tasks_.values()) {
+      QList<Task> tasks = tasks_.values();
+      for (const Task &task : tasks) {
         if (task.id != id && task.blocks_collection_scans) {
           resume_collection_watchers = false;
           break;