verilator/test_regress/t/t_preproc_debugi.v

// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under the Creative Commons Public Domain, for
// any use, without warranty, 2009 by Wilson Snyder.
// SPDX-License-Identifier: CC0-1.0

`define FOO
`define BAR(aa,bb) aa bb
`FOO
`BAR(aa,bb)

`ifdef FOO
`else
`endif
`ifndef FOO
`elsif FOO
`endif

`define STRINGIFY(x) `"x`"
`define CONCAT(a, b) a``b
`STRINGIFY(x)
`CONCAT(x,y)

`undef FOO

`undefineall

`ifdef NEVER
`error "should not get"
`endif