verilator/test_regress/t/t_class_extern_bad.v

// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under the Creative Commons Public Domain, for
// any use, without warranty, 2020 by Wilson Snyder.
// SPDX-License-Identifier: CC0-1.0

class Base1;
  extern task nodef();
  extern task nodef();  // <--- Error: duplicate
endclass

task Base1::noproto();  // <--- Error: Missing prototype
endtask

module t;
endmodule