const reference conversion

src/db/plugins/simple/SimpleDatabasePlugin.cxx

@@ -316,7 +316,7 @@ SimpleDatabase::Visit(const DatabaseSelection &selection,
 
 	if (r.rest.find('/') == std::string_view::npos) {
 		if (visit_song) {
-			Song *song = r.directory->FindSong(r.rest);
+			const Song *song = r.directory->FindSong(r.rest);
 			if (song != nullptr) {
 				const auto song2 = song->Export();
 				if (selection.Match(song2))

src/db/update/UpdateIO.cxx

@@ -84,7 +84,7 @@ try {
 }
 
 bool
-directory_child_access(Storage &storage, const Directory &directory,
+directory_child_access(const Storage &storage, const Directory &directory,
 		       std::string_view name, int mode) noexcept
 {
 #ifdef _WIN32

src/db/update/UpdateIO.hxx

@@ -55,7 +55,7 @@ directory_child_is_regular(Storage &storage, const Directory &directory,
  */
 [[gnu::pure]]
 bool
-directory_child_access(Storage &storage, const Directory &directory,
+directory_child_access(const Storage &storage, const Directory &directory,
 		       std::string_view name, int mode) noexcept;
 
 #endif

src/input/cache/Stream.cxx

@@ -24,7 +24,7 @@ CacheInputStream::CacheInputStream(InputCacheLease _lease,
 	:InputStream(_lease->GetUri(), _mutex),
 	 InputCacheLease(std::move(_lease))
 {
-	auto &i = GetCacheItem();
+	const auto &i = GetCacheItem();
 	size = i.size();
 	seekable = true;
 	SetReady();