Fix enum item references in class extends with parameters.

Changes

@@ -84,6 +84,7 @@ Verilator 5.043 devel
 * Fix DFG assertion on out-of-bounds selects. [Geza Lore]
 * Fix crash when super.new() called without a base class (#6772). [Matthew Ballance]
 * Fix class-in-class extends with parameters (#6773).
+* Fix enum item references in class extends with parameters.
 
 
 Verilator 5.042 2025-11-02

src/V3AstNodeExpr.h

@@ -1285,11 +1285,13 @@ public:
     bool cleanOut() const override { return true; }
 };
 class AstEnumItemRef final : public AstNodeExpr {
-    // @astgen ptr := m_itemp : AstEnumItem  // [AfterLink] Pointer to item
+    // @astgen ptr := m_itemp : Optional[AstEnumItem]  // [AfterLink] Pointer to item
     // @astgen ptr := m_classOrPackagep : Optional[AstNodeModule]  // Class/package defined in
+    string m_name;  // Name of enum (for param relink)
 public:
     AstEnumItemRef(FileLine* fl, AstEnumItem* itemp, AstNodeModule* classOrPackagep)
         : ASTGEN_SUPER_EnumItemRef(fl)
+        , m_name{itemp->name()}
         , m_itemp{itemp}
         , m_classOrPackagep{classOrPackagep} {
         dtypeFrom(m_itemp);
@@ -1297,13 +1299,14 @@ public:
     ASTGEN_MEMBERS_AstEnumItemRef;
     void dump(std::ostream& str) const override;
     void dumpJson(std::ostream& str) const override;
-    string name() const override VL_MT_STABLE { return itemp() ? itemp()->name() : "<null>"; }
+    string name() const override VL_MT_STABLE { return itemp() ? itemp()->name() : m_name; }
     int instrCount() const override { return 0; }
     bool sameNode(const AstNode* samep) const override {
         const AstEnumItemRef* const sp = VN_DBG_AS(samep, EnumItemRef);
         return itemp() == sp->itemp();
     }
     AstEnumItem* itemp() const VL_MT_STABLE { return m_itemp; }
+    void itemp(AstEnumItem* nodep) { m_itemp = nodep; }
     string emitVerilog() override { V3ERROR_NA_RETURN(""); }
     string emitC() override { V3ERROR_NA_RETURN(""); }
     bool cleanOut() const override { return true; }
@@ -1691,8 +1694,6 @@ class AstLambdaArgRef final : public AstNodeExpr {
     // Lambda argument usage
     // These are not AstVarRefs because we need to be able to delete/clone lambdas during
     // optimizations and AstVar's are painful to remove.
-
-private:
     string m_name;  // Name of variable
     bool m_index;  // Index, not value
 

src/V3LinkDot.cpp

@@ -4370,8 +4370,25 @@ class LinkDotResolveVisitor final : public VNVisitor {
         }
     }
     void visit(AstEnumItemRef* nodep) override {
-        // EnumItemRef may be under a dot.  Should already be resolved.
+        // Resolve its reference
+        // EnumItemRefs are created by the first pass, but V3Param may regenerate due to
+        // a parameterized class/module, so we shouldn't get can't find errors.
+        // No checkNoDot; created and iterated from a parseRef
         LINKDOT_VISIT_START();
+        if (!nodep->itemp()) {
+            UINFO(9, indent() << "linkEnumRef se" << cvtToHex(m_curSymp) << "  n=" << nodep);
+            UASSERT_OBJ(m_curSymp, nodep, "nullptr lookup symbol table");
+            VSymEnt* const foundp = m_curSymp->findIdFallback(nodep->name());
+            if (AstEnumItem* const itemp = foundp ? VN_CAST(foundp->nodep(), EnumItem) : nullptr) {
+                nodep->itemp(itemp);
+                nodep->classOrPackagep(foundp->classOrPackagep());
+                UINFO(9, indent() << " resolved " << nodep);
+            }
+            if (VL_UNCOVERABLE(!nodep->itemp())) {
+                nodep->v3error("Can't find definition of enum item, again: "  // LCOV_EXCL_LINE
+                               << nodep->prettyNameQ());
+            }
+        }
         iterateChildren(nodep);
     }
     void visit(AstMethodCall* nodep) override {

src/V3Param.cpp

@@ -2032,8 +2032,12 @@ public:
         }
         // Set all links pointing to a user3 (deleting) node as null
         netlistp->foreach([](AstNode* const nodep) {
-            nodep->foreachLink([](AstNode** const linkpp, const char*) {
-                if (*linkpp && (*linkpp)->user3()) *linkpp = nullptr;
+            nodep->foreachLink([&](AstNode** const linkpp, const char*) {
+                if (*linkpp && (*linkpp)->user3()) {
+                    UINFO(9, "clear   link " << nodep);
+                    *linkpp = nullptr;
+                    UINFO(9, "cleared link " << nodep);
+                }
             });
         });
     }

src/V3Width.cpp

@@ -2817,6 +2817,7 @@ class WidthVisitor final : public VNVisitor {
         }
     }
     void visit(AstEnumItemRef* nodep) override {
+        UASSERT_OBJ(nodep->itemp(), nodep, "Unlinked");
         if (!nodep->itemp()->didWidth()) {
             // We need to do the whole enum en masse
             AstNode* enump = nodep->itemp();

test_regress/t/t_enum_param_class2.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_enum_param_class2.v

@@ -0,0 +1,34 @@
+// 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
+
+// verilog_format: off
+`define stop $stop
+`define checkd(gotv,expv) do if ((gotv) !== (expv)) begin $write("%%Error: %s:%0d:  got=%0d exp=%0d (%s !== %s)\n", `__FILE__,`__LINE__, (gotv), (expv), `"gotv`", `"expv`"); `stop; end while(0);
+// verilog_format: on
+
+package uvm_pkg;
+  class uvm_reg_sequence #(
+      type BASE = int
+  );
+    typedef enum {
+      LOCAL = 2,
+      UPSTREAM = 3
+    } seq_parent_e;
+  endclass
+endpackage
+
+module t;
+  import uvm_pkg::*;
+  class test_seq extends uvm_reg_sequence;
+  endclass
+  initial begin
+    test_seq c;
+    c = new;
+    `checkd(c.LOCAL, 2);
+    `checkd(c.UPSTREAM, 3);
+    $finish;
+  end
+endmodule