Fix code style and errors

src/core/application.cpp

@@ -72,7 +72,7 @@ bool Application::kIsPortable = false;
 
 class ApplicationImpl {
  public:
-  ApplicationImpl(Application *app) :
+  explicit ApplicationImpl(Application *app) :
        tag_reader_client_([=]() {
           TagReaderClient *client = new TagReaderClient(app);
           app->MoveToNewThread(client);

src/core/commandlineoptions.cpp

@@ -312,8 +312,8 @@ bool CommandlineOptions::is_empty() const {
          seek_to_ == -1 &&
          seek_by_ == 0 &&
          play_track_at_ == -1 &&
-         show_osd_ == false &&
-         toggle_pretty_osd_ == false &&
+         !show_osd_ &&
+         !toggle_pretty_osd_ &&
          urls_.isEmpty();
 }
 

src/core/mainwindow.cpp

@@ -1321,7 +1321,7 @@ void MainWindow::AddToPlaylist(QAction *action) {
   }
 
   SongList songs;
-  for (PlaylistItemPtr item : items) {
+  for (const PlaylistItemPtr &item : items) {
     songs << item->Metadata();
   }
 
@@ -1587,7 +1587,7 @@ void MainWindow::EditTracks() {
 
 void MainWindow::EditTagDialogAccepted() {
 
-  for (PlaylistItemPtr item : edit_tag_dialog_->playlist_items()) {
+  for (const PlaylistItemPtr &item : edit_tag_dialog_->playlist_items()) {
     item->Reload();
   }
 
@@ -2256,7 +2256,7 @@ void MainWindow::AutoCompleteTags() {
 
 void MainWindow::AutoCompleteTagsAccepted() {
 
-  for (PlaylistItemPtr item : autocomplete_tag_items_) {
+  for (const PlaylistItemPtr &item : autocomplete_tag_items_) {
     item->Reload();
   }
 

src/core/player.cpp

@@ -81,6 +81,8 @@ const char *Player::kSettingsGroup = "Player";
 Player::Player(Application *app, QObject *parent)
     : PlayerInterface(parent),
     app_(app),
+    analyzer_(nullptr),
+    equalizer_(nullptr),
     stream_change_type_(Engine::First),
     last_state_(Engine::Empty),
     nb_errors_received_(0),

src/core/songloader.cpp

@@ -257,7 +257,7 @@ void SongLoader::LoadLocalAsync(const QString &filename) {
     cue.open(QIODevice::ReadOnly);
 
     SongList song_list = cue_parser_->Load(&cue, matching_cue, QDir(filename.section('/', 0, -2)));
-    for (Song song: song_list){
+    for (const Song &song : song_list) {
       if (song.is_valid()) songs_ << song;
     }
     return;

src/core/utilities.cpp

@@ -263,7 +263,7 @@ bool RemoveRecursive(const QString &path) {
       return false;
   }
 
-  if (!dir.rmdir(path)) return false;
+  return dir.rmdir(path);
 
   return true;