Allow yields inside '__pairs'

lbaselib.c

@@ -261,6 +261,11 @@ 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;
+}
+
 static int luaB_pairs (lua_State *L) {
   luaL_checkany(L, 1);
   if (luaL_getmetafield(L, 1, "__pairs") == LUA_TNIL) {  /* no metamethod? */
@@ -270,7 +275,7 @@ static int luaB_pairs (lua_State *L) {
   }
   else {
     lua_pushvalue(L, 1);  /* argument 'self' to metamethod */
-    lua_call(L, 1, 3);  /* get 3 values from metamethod */
+    lua_callk(L, 1, 3, 0, pairscont);  /* get 3 values from metamethod */
   }
   return 3;
 }