// __LINE__ = `__LINE__
`ifdef __LINE__
// This block SHOULD be emitted from the preprocessor.
`elsif UNDEFINED
// NOT emitted.
`endif
`ifndef __LINE__
// This block should NOT be emitted from the preprocessor.
// However, following (conditional) definition should make it through the
// preprocessor parsing stage without error.
`define __LINE__ -1
`elsif UNDEFINED
// Emitted instead.
`endif
// The following define should have no effect.
`define __LINE__ -2
// The following undef should have no effect.
`undef __LINE__
module M;
initial
if (`__LINE__ == 28) // Should be "26 == 28".
$display("PASS");
else if (`__LINE__ == 28) // Should be "28 == 28".
$display("FAIL");
endmodule