Fix nested random dynamic arrays internal error (#8438) (#8439)

src/V3Randomize.cpp

@@ -3652,6 +3652,7 @@ class RandomizeVisitor final : public VNVisitor {
 
     // STATE
     V3UniqueNames m_inlineUniqueNames;  // For generating unique function names
+    V3UniqueNames m_randArrayUniqueNames{"__Vrandarr"};  // Random array loop indices
     V3UniqueNames m_modeUniqueNames{"__Vmode"};  // For generating unique rand/constraint
                                                  // mode state var names
     V3UniqueNames m_inlineUniqueStdName{"__VStdrand"};
@@ -4234,15 +4235,14 @@ class RandomizeVisitor final : public VNVisitor {
     }
     AstNodeStmt* createArrayForeachLoop(FileLine* const fl, AstNodeDType* const dtypep,
                                         AstNodeExpr* exprp, AstVar* const outputVarp) {
-        V3UniqueNames uniqueNames{"__Vrandarr"};
         AstNodeDType* tempDTypep = dtypep;
         AstVar* randLoopIndxp = nullptr;
         auto createLoopIndex = [&](AstNodeDType* tempDTypep) {
             if (VN_IS(tempDTypep, AssocArrayDType)) {
-                return new AstVar{fl, VVarType::VAR, uniqueNames.get(""),
+                return new AstVar{fl, VVarType::VAR, m_randArrayUniqueNames.get(""),
                                   VN_AS(tempDTypep, AssocArrayDType)->keyDTypep()};
             }
-            return new AstVar{fl, VVarType::VAR, uniqueNames.get(""),
+            return new AstVar{fl, VVarType::VAR, m_randArrayUniqueNames.get(""),
                               dtypep->findBasicDType(VBasicDTypeKwd::UINT32)};
         };
         AstNodeExpr* tempElementp = nullptr;
@@ -5675,8 +5675,10 @@ class RandomizeVisitor final : public VNVisitor {
     void visit(AstNodeModule* nodep) override {
         VL_RESTORER(m_modp);
         VL_RESTORER(m_randCaseNum);
+        VL_RESTORER_COPY(m_randArrayUniqueNames);
         m_modp = nodep;
         m_randCaseNum = 0;
+        m_randArrayUniqueNames.reset();
         iterateChildren(nodep);
     }
     void visit(AstNodeFTask* nodep) override {

test_regress/t/t_randomize_nested_dynamic_array.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# 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-FileCopyrightText: 2026 Wilson Snyder
+# 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_nested_dynamic_array.v

@@ -0,0 +1,24 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2026 by Verilator Authors.
+// SPDX-FileCopyrightText: 2026 Wilson Snyder
+// SPDX-License-Identifier: CC0-1.0
+
+typedef struct {
+  rand bit values[];
+} Element;
+
+class Container;
+  rand Element elements[];
+endclass
+
+module t;
+  initial begin
+    automatic Container object = new;
+    void'(object.randomize());
+
+    $write("*-* All Finished *-*\n");
+    $finish;
+  end
+endmodule