%Warning-WIDTHCONCAT: t/t_packed_concat_bad.v:16: Unsized numbers/parameters not allowed in replications.
                                                : ... In instance t
   localparam bit_int_t [1:0] count_bits = {2{$bits(count_t)}};
                                              ^~~~~
                      ... Use "/* verilator lint_off WIDTHCONCAT */" and lint_on around source to disable this message.
%Warning-WIDTHCONCAT: t/t_packed_concat_bad.v:17: Unsized numbers/parameters not allowed in concatenations.
                                                : ... In instance t
   localparam bit_int_t [1:0] count_bitsc = {$bits(count_t), $bits(count_t)};
                                             ^~~~~
%Warning-WIDTHCONCAT: t/t_packed_concat_bad.v:17: Unsized numbers/parameters not allowed in replications.
                                                : ... In instance t
   localparam bit_int_t [1:0] count_bitsc = {$bits(count_t), $bits(count_t)};
                                                           ^
%Error: Exiting due to