%Warning-UNOPTFLAT: t/t_unopt_combo.v:23:25: Signal unoptimizable: Circular combinational logic: 't.b' 23 | wire [31:0] b; | ^ ... For warning description see https://verilator.org/warn/UNOPTFLAT?v=latest ... Use "/* verilator lint_off UNOPTFLAT */" and lint_on around source to disable this message. t/t_unopt_combo.v:23:25: Example path: t.b t/t_unopt_combo.v:124:4: Example path: ALWAYS t/t_unopt_combo.v:24:25: Example path: t.c t/t_unopt_combo.v:81:4: Example path: ALWAYS t/t_unopt_combo.v:23:25: Example path: t.b %Error: Exiting due to