verilator/test_regress/t/t_fork_dynscope.v

// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under the Creative Commons Public Domain, for
// any use, without warranty, 2023 by Antmicro Ltd.
// SPDX-License-Identifier: CC0-1.0

class Foo;
  task do_something(int arg_v);
    int dynscope_var;
    int x;
    dynscope_var = 0;

    fork
      #10 begin
        x = 0;
        // Test capturing a variable that needs to be modified
        $display("Incremented dynscope_var: %d", ++dynscope_var);
        if (dynscope_var != 1)
          $stop;

        // Check nested access
        fork
          #10 begin
            $display("Incremented x: %d", ++x);
            $display("Incremented dynscope_var: %d", ++dynscope_var);
            if (dynscope_var != 2)
              $stop;
          end
        join_none
      end
      #10 begin
        // Same as the first check, but with an argument
        // (so it needs to be copied to the dynamic scope instead of being moved there)
        $display("Incremented arg_v: %d", ++arg_v);
        if (arg_v != 2)
          $stop;
      end
    join_none

    // Check if regular access to arg_v has been substituted with access to its copy from
    // a dynamic scope
    $display("Incremented arg_v: %d", ++arg_v);
    if (arg_v != 1)
      $stop;
  endtask
endclass

module t();
  initial begin
    Foo foo;
    foo = new;
    foo.do_something(0);

    #99 begin
      $write("*-* All Finished *-*\n");
      $finish;
    end
  end
endmodule