Improve to throw UNSUPPORTED instead of syntax error on extend class arguments

src/verilog.y

@@ -7190,6 +7190,15 @@ classExtendsOne<classExtendsp>:         // IEEE: part of class_declaration
                 class_typeExtImpList
                         { $$ = new AstClassExtends{$1->fileline(), $1, GRAMMARP->m_inImplements};
                           $<scp>$ = $<scp>1; }
+        |       class_typeExtImpList '(' list_of_argumentsE ')'
+                        { $$ = new AstClassExtends{$1->fileline(), $1, GRAMMARP->m_inImplements};
+                          BBUNSUP($<fl>2, "Unsupported: 'extends' with class list_of_arguments");
+                          $<scp>$ = $<scp>1; }
+        //                      // IEEE-2023: Added: yEXTENDS class_type '(' yDEFAULT ')'
+        |       class_typeExtImpList '(' yDEFAULT ')'
+                        { $$ = new AstClassExtends{$1->fileline(), $1, GRAMMARP->m_inImplements};
+                          BBUNSUP($<fl>2, "Unsupported: 'extends' with 'default'");
+                          $<scp>$ = $<scp>1; }
         ;
 
 classImplementsE<classExtendsp>:        // IEEE: part of class_declaration

test_regress/t/t_class_extends_arg.out

@@ -0,0 +1,8 @@
+%Error-UNSUPPORTED: t/t_class_extends_arg.v:14:25: Unsupported: 'extends' with 'default'
+   14 | class Cls1 extends Base1(default);
+      |                         ^
+                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
+%Error-UNSUPPORTED: t/t_class_extends_arg.v:18:25: Unsupported: 'extends' with class list_of_arguments
+   18 | class Cls5 extends Base1(5);
+      |                         ^
+%Error: Exiting due to

test_regress/t/t_class_extends_arg.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2024 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+import vltest_bootstrap
+
+test.scenarios('linter')
+
+test.lint(fails=test.vlt_all, expect_filename=test.golden_filename)
+
+test.passes()

test_regress/t/t_class_extends_arg.v

@@ -0,0 +1,36 @@
+// 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;
+   int s = 2;
+   function new(int def = 3);
+      s = def;
+   endfunction
+endclass
+
+class Cls1 extends Base1(default);
+   // Gets new(int def)
+endclass
+
+class Cls5 extends Base1(5);
+   // Gets new()
+endclass
+
+module t (/*AUTOARG*/);
+   initial begin
+      Cls1 c1;
+      Cls1 c5;
+      c1 = new(57);
+      if (c1.s !== 57) $stop;
+
+      c5 = new;
+      if (c5.s !== 5) $stop;
+
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+
+endmodule