%Warning-IMPLICIT: t/t_lint_implicit_def_bad.v:12: Signal definition not found, creating implicitly: 'imp_warn'
   assign imp_warn = 1'b1;
          ^~~~~~~~
                   ... Use "/* verilator lint_off IMPLICIT */" and lint_on around source to disable this message.
%Error: t/t_lint_implicit_def_bad.v:17: Signal definition not found, and implicit disabled with `default_nettype: 'imp_err'
   assign imp_err = 1'b1;
          ^~~~~~~
%Error: Exiting due to