verilator/test_regress/t/t_interface_nest.v

// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under the Creative Commons Public Domain, for
// SPDX-FileCopyrightText: 2017
// SPDX-License-Identifier: CC0-1.0

interface if1;
  integer var1;
endinterface

interface if2;
  if1 i1 ();
  integer var2;
endinterface

module mod1 (
    input clk,
    input integer modnum,  // Don't use parameter, want same module twice for better checking
    if2 foo
);

  logic l1, l2;

  always_ff @(posedge clk) begin
    if (modnum == 1) begin
      if (foo.i1.var1 != 1) $stop;
      if (foo.var2 != 2) $stop;
    end
    if (modnum == 2) begin
      if (foo.i1.var1 != 1) $stop;
      if (foo.var2 != 2) $stop;
    end
  end

endmodule

module t (  /*AUTOARG*/
    // Inputs
    clk
);
  input clk;

  if2 i2a ();
  if2 i2b ();

  assign i2a.i1.var1 = 1;
  assign i2a.var2 = 2;
  assign i2b.i1.var1 = 3;
  assign i2b.var2 = 4;

  mod1 mod1a (
      .modnum(1),
      .clk(clk),
      .foo(i2a)
  );

  mod1 mod1b (
      .modnum(2),
      .clk(clk),
      .foo(i2a)
  );

  integer cyc = 0;
  always_ff @(posedge clk) begin
    cyc <= cyc + 1;
    if (cyc == 2) begin
      $write("*-* All Finished *-*\n");
      $finish;
    end
  end

endmodule