Add missing const

src/settings/appearancesettingspage.cpp

@@ -21,6 +21,8 @@
 
 #include "config.h"
 
+#include <utility>
+
 #include <QApplication>
 #include <QWidget>
 #include <QStyleFactory>
@@ -91,7 +93,8 @@ AppearanceSettingsPage::AppearanceSettingsPage(SettingsDialog *dialog, QWidget *
   setWindowIcon(IconLoader::Load(QStringLiteral("view-media-visualization"), true, 0, 32));
 
   ui_->combobox_style->addItem(QStringLiteral("default"), QStringLiteral("default"));
-  for (const QString &style : QStyleFactory::keys()) {
+  const QStringList styles = QStyleFactory::keys();
+  for (const QString &style : styles) {
     ui_->combobox_style->addItem(style, style);
   }
 

src/settings/backendsettingspage.cpp

@@ -19,6 +19,8 @@
 
 #include "config.h"
 
+#include <utility>
+
 #include <QtGlobal>
 #include <QWidget>
 #include <QSettings>
@@ -308,7 +310,8 @@ void BackendSettingsPage::Load_Output(QString output, QVariant device) {
   if (output.isEmpty()) output = engine()->DefaultOutput();
 
   ui_->combobox_output->clear();
-  for (const EngineBase::OutputDetails &o : engine()->GetOutputsList()) {
+  const EngineBase::OutputDetailsList outputs = engine()->GetOutputsList();
+  for (const EngineBase::OutputDetails &o : outputs) {
     ui_->combobox_output->addItem(IconLoader::Load(o.iconname), o.description, QVariant::fromValue(o));
   }
   if (ui_->combobox_output->count() > 1) ui_->combobox_output->setEnabled(true);
@@ -370,9 +373,11 @@ void BackendSettingsPage::Load_Device(const QString &output, const QVariant &dev
 #endif
     ui_->combobox_device->addItem(IconLoader::Load(QStringLiteral("soundcard")), QLatin1String(kOutputAutomaticallySelect), QVariant());
 
-  for (DeviceFinder *f : dialog()->app()->device_finders()->ListFinders()) {
+  const QList<DeviceFinder*> device_finders = dialog()->app()->device_finders()->ListFinders();
+  for (DeviceFinder *f : device_finders) {
     if (!f->outputs().contains(output)) continue;
-    for (const EngineDevice &d : f->ListDevices()) {
+    const EngineDeviceList engine_devices = f->ListDevices();
+    for (const EngineDevice &d : engine_devices) {
       devices++;
       ui_->combobox_device->addItem(IconLoader::Load(d.iconname), d.description, d.value);
       if (d.value == device) { df_device = d; }

src/settings/behavioursettingspage.cpp

@@ -22,6 +22,7 @@
 #include "config.h"
 
 #include <algorithm>
+#include <utility>
 
 #include <QVariant>
 #include <QString>
@@ -80,12 +81,12 @@ BehaviourSettingsPage::BehaviourSettingsPage(SettingsDialog *dialog, QWidget *pa
   // Populate the language combo box.  We do this by looking at all the compiled in translations.
   QDir dir1(QStringLiteral(":/translations/"));
   QDir dir2(QStringLiteral(TRANSLATIONS_DIR));
-  QStringList codes(dir1.entryList(QStringList() << QStringLiteral("*.qm")));
+  QStringList codes = dir1.entryList(QStringList() << QStringLiteral("*.qm"));
   if (dir2.exists()) {
     codes << dir2.entryList(QStringList() << QStringLiteral("*.qm"));
   }
   QRegularExpression lang_re(QStringLiteral("^strawberry_(.*).qm$"));
-  for (const QString &filename : codes) {
+  for (const QString &filename : std::as_const(codes)) {
 
     QRegularExpressionMatch re_match = lang_re.match(filename);
 

src/settings/collectionsettingspage.cpp

@@ -21,6 +21,7 @@
 
 #include "config.h"
 
+#include <utility>
 #include <limits>
 
 #include <QStandardPaths>
@@ -136,7 +137,8 @@ void CollectionSettingsPage::Load() {
   }
 
   ui_->list->model()->removeRows(0, ui_->list->model()->rowCount());
-  for (const QString &path : collection_directory_model_->paths()) {
+  const QStringList paths = collection_directory_model_->paths();
+  for (const QString &path : paths) {
     collectionsettings_directory_model_->AddDirectory(path);
   }
 
@@ -229,13 +231,15 @@ void CollectionSettingsPage::Save() {
 
   s.endGroup();
 
-  for (const CollectionDirectory &dir : collection_directory_model_->directories()) {
+  const QMap<int, CollectionDirectory> dirs = collection_directory_model_->directories();
+  for (const CollectionDirectory &dir : dirs) {
     if (!collectionsettings_directory_model_->paths().contains(dir.path)) {
       collection_backend_->RemoveDirectoryAsync(dir);
     }
   }
 
-  for (const QString &path : collectionsettings_directory_model_->paths()) {
+  const QStringList paths = collectionsettings_directory_model_->paths();
+  for (const QString &path : paths) {
     if (!collection_directory_model_->paths().contains(path)) {
       collection_backend_->AddDirectoryAsync(path);
     }

src/settings/settingspage.cpp

@@ -56,7 +56,7 @@ void SettingsPage::Init(QWidget *ui_widget) {
   sliders_.clear();
   lineedits_.clear();
 
-  QList<QWidget*> list = ui_widget_->findChildren<QWidget*>(QString(), Qt::FindChildrenRecursively);
+  const QList<QWidget*> list = ui_widget_->findChildren<QWidget*>(QString(), Qt::FindChildrenRecursively);
   for (QWidget *w : list) {
     if (QCheckBox *checkbox = qobject_cast<QCheckBox*>(w)) {
       checkboxes_ << qMakePair(checkbox, checkbox->checkState());