uclex.cc:1384:2: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
        register yy_state_type yy_current_state;
        ^~~~~~~~~
uclex.cc:1385:2: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
        register char *yy_cp, *yy_bp;
        ^~~~~~~~~
uclex.cc:1385:2: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
        register char *yy_cp, *yy_bp;
        ^~~~~~~~~
uclex.cc:1386:2: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
        register int yy_act;
        ^~~~~~~~~
uclex.cc:1435:4: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
                        register YY_CHAR yy_c = yy_ec[YY_SC_TO_UI(*yy_cp)];
                        ^~~~~~~~~
uclex.cc:2502:6: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
        register char *dest = YY_CURRENT_BUFFER_LVALUE->yy_ch_buf;
        ^~~~~~~~~
uclex.cc:2503:2: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
        register char *source = (yytext_ptr);
        ^~~~~~~~~
uclex.cc:2504:2: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
        register int number_to_move, i;
        ^~~~~~~~~
uclex.cc:2504:2: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
        register int number_to_move, i;
        ^~~~~~~~~
uclex.cc:2636:2: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
        register yy_state_type yy_current_state;
        ^~~~~~~~~
uclex.cc:2637:2: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
        register char *yy_cp;
        ^~~~~~~~~
uclex.cc:2643:3: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
                register YY_CHAR yy_c = (*yy_cp ? yy_ec[YY_SC_TO_UI(*yy_...
                ^~~~~~~~~
uclex.cc:2668:2: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
        register int yy_is_jam;
        ^~~~~~~~~
uclex.cc:2669:6: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
        register char *yy_cp = (yy_c_buf_p);
        ^~~~~~~~~
uclex.cc:2671:2: error: ISO C++17 does not allow 'register' storage class
      specifier [-Wregister]
        register YY_CHAR yy_c = 1;
        ^~~~~~~~~