+ /* Start YYX at -YYN if negative to avoid negative indexes in
+ YYCHECK. */
+ int xbegin = n_ < 0 ? -n_ : 0;
+ /* Stay within bounds of both yycheck and yytname. */
+ int checklim = last_ - n_;
+ int xend = checklim < ntokens_ ? checklim : ntokens_;
+ for (int x = xbegin; x < xend; ++x)