%Warning-UNDRIVEN: t/t_lint_unused_iface_bad.v:7:10: Signal is not driven: 'sig_udrv'
                                                   : ... In instance t.sub
   logic sig_udrv;
         ^~~~~~~~
                   ... Use "/* verilator lint_off UNDRIVEN */" and lint_on around source to disable this message.
%Warning-UNUSED: t/t_lint_unused_iface_bad.v:8:10: Signal is not used: 'sig_uusd'
                                                 : ... In instance t.sub
   logic sig_uusd;
         ^~~~~~~~
%Error: Exiting due to