'__pairs' can also return a to-be-closed object

lbaselib.c

@@ -279,21 +279,22 @@ static int luaB_next (lua_State *L) {
 
 static int pairscont (lua_State *L, int status, lua_KContext k) {
   (void)L; (void)status; (void)k;  /* unused */
-  return 3;
+  return 4;  /* __pairs did all the work, just return its results */
 }
 
 static int luaB_pairs (lua_State *L) {
   luaL_checkany(L, 1);
   if (luaL_getmetafield(L, 1, "__pairs") == LUA_TNIL) {  /* no metamethod? */
-    lua_pushcfunction(L, luaB_next);  /* will return generator, */
-    lua_pushvalue(L, 1);  /* state, */
-    lua_pushnil(L);  /* and initial value */
+    lua_pushcfunction(L, luaB_next);  /* will return generator and */
+    lua_pushvalue(L, 1);  /* state */
+    lua_pushnil(L);  /* initial value */
+    lua_pushnil(L);  /* to-be-closed object */
   }
   else {
     lua_pushvalue(L, 1);  /* argument 'self' to metamethod */
-    lua_callk(L, 1, 3, 0, pairscont);  /* get 3 values from metamethod */
+    lua_callk(L, 1, 4, 0, pairscont);  /* get 4 values from metamethod */
   }
-  return 3;
+  return 4;
 }