db/DatabaseSong: DatabaseDetachSong(uri) returns instance, not pointer

src/SongLoader.cxx

@@ -41,7 +41,7 @@ SongLoader::LoadFromDatabase(const char *uri) const
 {
 #ifdef ENABLE_DATABASE
 	if (db != nullptr)
-		return DatabaseDetachSong(*db, *storage, uri);
+		return new DetachedSong(DatabaseDetachSong(*db, *storage, uri));
 #else
 	(void)uri;
 #endif

src/db/DatabaseSong.cxx

@@ -41,7 +41,7 @@ DatabaseDetachSong(const Storage &storage, const LightSong &song)
 	return detached;
 }
 
-DetachedSong *
+DetachedSong
 DatabaseDetachSong(const Database &db, const Storage &storage, const char *uri)
 {
 	const LightSong *tmp = db.GetSong(uri);
@@ -49,5 +49,5 @@ DatabaseDetachSong(const Database &db, const Storage &storage, const char *uri)
 
 	AtScopeExit(&db, tmp) { db.ReturnSong(tmp); };
 
-	return new DetachedSong(DatabaseDetachSong(storage, *tmp));
+	return DatabaseDetachSong(storage, *tmp);
 }

src/db/DatabaseSong.hxx

@@ -37,12 +37,12 @@ DatabaseDetachSong(const Storage &storage, const LightSong &song);
 
 /**
  * Look up a song in the database and convert it to a #DetachedSong
- * instance.  The caller is responsible for freeing it.
+ * instance.
  *
- * @return nullptr on error
+ * Throws std::runtime_error on error.
  */
-gcc_malloc gcc_nonnull_all
-DetachedSong *
+gcc_pure
+DetachedSong
 DatabaseDetachSong(const Database &db, const Storage &storage,
 		   const char *uri);
 

test/test_translate_song.cxx

@@ -107,15 +107,15 @@ MakeTag2c()
 static const char *uri1 = "/foo/bar.ogg";
 static const char *uri2 = "foo/bar.ogg";
 
-DetachedSong *
+DetachedSong
 DatabaseDetachSong(gcc_unused const Database &db,
 		   gcc_unused const Storage &_storage,
 		   const char *uri)
 {
 	if (strcmp(uri, uri2) == 0)
-		return new DetachedSong(uri, MakeTag2a());
+		return DetachedSong(uri, MakeTag2a());
 
-	return nullptr;
+	throw std::runtime_error("No such song");
 }
 
 bool