Fix pre/post_randomize on extended classes (#6467).

Changes

@@ -45,6 +45,7 @@ Verilator 5.043 devel
 * Optimize trace initialization code size (#6749). [Geza Lore]
 * Fix extern function that returns parameterized class (#4924).
 * Fix randomize called within func/task (#6144) (#6753). [Yilou Wang]
+* Fix pre/post_randomize on extended classes (#6467). [Alex Solomatnikov]
 * Fix expression short circuiting (#6483). [Todd Strader]
 * Fix expression coverage of system calls (#6592). [Todd Strader]
 * Fix `--timing` with `--x-initial-edge` (#6603) (#6631). [Krzysztof Bieganski, Antmicro Ltd.]
@@ -64,7 +65,7 @@ Verilator 5.043 devel
 * Fix splitting of Syms constructor/destructor bodies (#6662). [Geza Lore, Fractile Ltd.]
 * Fix long C++ compilation due to VerilatedScope constructors (#6664). [Geza Lore, Fractile Ltd.]
 * Fix large array initialization (#6669). [Artur Bieniek, Antmicro Ltd.]
-* Fix --expand-limit not respected for expressions (#6670). [Geza Lore, Fractile Ltd.]
+* Fix `--expand-limit` not respected for expressions (#6670). [Geza Lore, Fractile Ltd.]
 * Fix `free` name collision (#6675). [Todd Strader]
 * Fix bounds checking in non-inlined function (#6677). [Geza Lore, Fractile Ltd.]
 * Fix stream operator widening (#6693) (#6697). [Jean-Nicolas Strauss]

src/V3LinkDot.cpp

@@ -4622,9 +4622,25 @@ class LinkDotResolveVisitor final : public VNVisitor {
                     }
                 } else if (VN_IS(nodep, New) && m_statep->forPrearray()) {
                     // Resolved in V3Width
+                } else if ((nodep->name() == "pre_randomize" || nodep->name() == "post_randomize")
+                           && VN_IS(dotSymp->nodep(), Class)) {
+                    AstClass* const classp = VN_AS(dotSymp->nodep(), Class);
+                    // Functions that might be defined by user, but if not, they get empty
+                    // definitions within referenced class.
+                    // TODO perhaps cleaner to add to symbol table up-front with
+                    // a lambda to construct them on a reference.
+                    AstFunc* const funcp
+                        = new AstFunc{nodep->fileline(), nodep->name(), nullptr, nullptr};
+                    funcp->classMethod(true);
+                    funcp->dtypep(funcp->findVoidDType());
+                    classp->addMembersp(funcp);
+                    m_statep->insertBlock(dotSymp, nodep->name(), funcp, classp);
+                    nodep->taskp(funcp);
+                    nodep->classOrPackagep(classp);
+                    UINFO(9, indent() << " Auto-made " << funcp);
+                    return;
                 } else if (nodep->name() == "randomize" || nodep->name() == "srandom"
                            || nodep->name() == "get_randstate" || nodep->name() == "set_randstate"
-                           || nodep->name() == "pre_randomize" || nodep->name() == "post_randomize"
                            || nodep->name() == "rand_mode" || nodep->name() == "constraint_mode") {
                     if (AstClass* const classp = VN_CAST(m_modp, Class)) {
                         nodep->classOrPackagep(classp);

test_regress/t/t_randomize_prepost.v

@@ -45,6 +45,25 @@ class Cls extends Base;
   endfunction
 endclass
 
+package emp_pkg;
+  virtual class emp_sequence #(
+      type REQ = int
+  );
+  endclass
+  class emp_txn;
+  endclass
+  class emp_base_sequence extends emp_sequence #(emp_txn);
+  endclass
+  class emp_base_port_seq extends emp_base_sequence;
+    function void pre_randomize();
+      super.pre_randomize();
+    endfunction
+    function void post_randomize();
+      super.post_randomize();
+    endfunction
+  endclass
+endpackage
+
 module t;
 
   initial begin

test_regress/t/t_randomize_prepost_super.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()
+
+test.execute()
+
+test.passes()

test_regress/t/t_randomize_prepost_super.v

@@ -0,0 +1,23 @@
+// 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
+
+module t;
+
+  virtual class uvm_object;
+  endclass
+
+  class config_obj extends uvm_object;
+    function void pre_randomize();
+      super.pre_randomize();
+    endfunction
+    function void post_randomize();
+      super.post_randomize();
+    endfunction
+  endclass
+
+  initial $finish;
+
+endmodule