%Warning-UNUSED: t/t_lint_once_bad.v:18: Signal is not driven, nor used: 'unus1'
                                       : ... In instance t.sub3
   reg [A:0] unus1;    reg [A:0] unus2;
             ^~~~~
                 ... Use "/* verilator lint_off UNUSED */" and lint_on around source to disable this message.
%Warning-UNUSED: t/t_lint_once_bad.v:18: Signal is not driven, nor used: 'unus2'
                                       : ... In instance t.sub3
   reg [A:0] unus1;    reg [A:0] unus2;
                                 ^~~~~
%Error: Exiting due to