module test; function f_0; input i; begin f_0 = f_1(i); end endfunction function f_1; input i; begin f_1 = !i; end endfunction wire w = f_0(1'b0); initial begin #1; if ( w !== 1'b1) $display ("FAILED w (%b) !== 1'b1", w); else $display ("PASSED"); end endmodule