Support generated classes (#5665).

Changes

@@ -13,6 +13,7 @@ Verilator 5.033 devel
 
 **Minor:**
 
+* Support generated classes (#5665). [Shou-Li Hsu]
 * Fix error message when call task as a function (#3089). [Matthew Ballance]
 * Fix V3Simulate constant reuse (#5709). [Geza Lore]
 * Fix man pages what-is section (#5710). [Ahmed El-Mahmoudy]

src/V3Begin.cpp

@@ -148,6 +148,18 @@ class BeginVisitor final : public VNVisitor {
     void visit(AstNodeModule* nodep) override {
         VL_RESTORER(m_modp);
         m_modp = nodep;
+        // Rename it (e.g. class under a generate)
+        if (m_unnamedScope != "") {
+            nodep->name(dot(m_unnamedScope, nodep->name()));
+            UINFO(8, "     rename to " << nodep->name() << endl);
+            m_statep->userMarkChanged(nodep);
+        }
+        VL_RESTORER(m_displayScope);
+        VL_RESTORER(m_namedScope);
+        VL_RESTORER(m_unnamedScope);
+        m_displayScope = "";
+        m_namedScope = "";
+        m_unnamedScope = "";
         iterateChildren(nodep);
     }
     void visit(AstNodeFTask* nodep) override {

test_regress/t/t_EXAMPLE.v

@@ -17,7 +17,8 @@
 // SPDX-License-Identifier: CC0-1.0
 
 `define stop $stop
-`define checkh(gotv,expv) do if ((gotv) !== (expv)) begin $write("%%Error: %s:%0d: got=%0x exp=%0x (%s !== %s)\n", `__FILE__,`__LINE__, (gotv), (expv), `"gotv`", `"expv`"); `stop; end while(0);
+`define checkh(gotv,expv) do if ((gotv) !== (expv)) begin $write("%%Error: %s:%0d:  got=%0x exp=%0x (%s !== %s)\n", `__FILE__,`__LINE__, (gotv), (expv), `"gotv`", `"expv`"); `stop; end while(0);
+`define checks(gotv,expv) do if ((gotv) != (expv)) begin $write("%%Error: %s:%0d:  got='%s' exp='%s'\n", `__FILE__,`__LINE__, (gotv), (expv)); `stop; end while(0);
 
 module t(/*AUTOARG*/
    // Inputs

test_regress/t/t_gen_class.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2025 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('simulator')
+
+test.compile(verilator_flags2=['--binary'])
+
+test.execute()
+
+test.passes()

test_regress/t/t_gen_class.v

@@ -0,0 +1,67 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+`define stop $stop
+`define checkh(gotv,expv) do if ((gotv) !== (expv)) begin $write("%%Error: %s:%0d:  got=%0x exp=%0x (%s !== %s)\n", `__FILE__,`__LINE__, (gotv), (expv), `"gotv`", `"expv`"); `stop; end while(0);
+`define checks(gotv,expv) do if ((gotv) != (expv)) begin $write("%%Error: %s:%0d:  got='%s' exp='%s'\n", `__FILE__,`__LINE__, (gotv), (expv)); `stop; end while(0);
+
+module Child;
+   int ch_value;
+endmodule
+
+module Parent;
+   for (genvar i = 0; i < 10; i++) begin : gen_child
+      Child child();
+   end
+endmodule
+
+module t;
+   Parent parent();
+
+   virtual class ChildAgentBase;
+      pure virtual task preload(int value);
+      pure virtual function string name();
+   endclass
+
+   ChildAgentBase child_agents[10];
+
+   for (genvar i = 0; i < 10; i++) begin : gfor
+      class ChildAgent extends ChildAgentBase;
+         task automatic preload(int value);
+            parent.gen_child[i].child.ch_value = value;
+         endtask
+         function string name();
+            return $sformatf("%m");
+         endfunction
+      endclass
+
+      ChildAgent agent = new();
+
+      initial child_agents[i] = agent;
+   end
+
+   task automatic preload_children;
+      for (int i = 0; i < 10; i++) begin
+         child_agents[i].preload(i);
+      end
+   endtask
+
+   string s;
+
+   initial begin
+      #1;  // Ensure all class instances are initialized
+      preload_children();
+      `checkh(parent.gen_child[3].child.ch_value, 3);
+      `checkh(parent.gen_child[8].child.ch_value, 8);
+`ifdef VERILATOR
+      // Some legal examples "t.gfor[4].\ChildAgent::name", "t.gfor[4].ChildAgent.name"
+      `checks(child_agents[4].name(), "t.gfor[4].ChildAgent.name");
+`endif
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+
+endmodule