Fix enum range constraints missing for rand variables in sub-objects (#7230) (#7235)

src/V3Randomize.cpp

@@ -4067,13 +4067,10 @@ class RandomizeVisitor final : public VNVisitor {
             // Restrict enum variables in solver to valid members only
             {
                 AstNodeModule* const genModp = VN_AS(genp->user2p(), NodeModule);
-                nodep->foreachMember([&](AstClass*, AstVar* memberVarp) {
-                    if (!memberVarp->user3()) return;
-                    AstEnumDType* const enumDtp
-                        = VN_CAST(memberVarp->dtypep()->skipRefToEnump(), EnumDType);
-                    if (!enumDtp) return;
+                // Emit enum range hard constraint for a single variable
+                const auto emitEnumConstraint = [&](const std::string& smtName,
+                                                    AstEnumDType* const enumDtp) {
                     const int width = enumDtp->width();
-                    const std::string smtName = memberVarp->name();
                     std::string constraint = "(__Vbv (or";
                     for (AstEnumItem* itemp = enumDtp->itemsp(); itemp;
                          itemp = VN_AS(itemp->nextp(), EnumItem)) {
@@ -4088,6 +4085,41 @@ class RandomizeVisitor final : public VNVisitor {
                         new AstCExpr{fl, AstCExpr::Pure{}, "\"" + constraint + "\""}};
                     callp->dtypeSetVoid();
                     randomizep->addStmtsp(callp->makeStmt());
+                };
+                // Recursively emit enum constraints for sub-object members
+                std::function<void(AstClass*, const std::string&)> addSubObjEnumConstraints
+                    = [&](AstClass* classp, const std::string& pathPrefix) {
+                          classp->foreachMember([&](AstClass*, AstVar* subVarp) {
+                              if (!subVarp->rand().isRandomizable()) return;
+                              const std::string smtName = pathPrefix + "." + subVarp->name();
+                              AstEnumDType* const enumDtp
+                                  = VN_CAST(subVarp->dtypep()->skipRefToEnump(), EnumDType);
+                              if (enumDtp) {
+                                  emitEnumConstraint(smtName, enumDtp);
+                                  return;
+                              }
+                              if (!subVarp->globalConstrained()) return;
+                              const AstNodeDType* const subDtypep = subVarp->dtypep()->skipRefp();
+                              const AstClassRefDType* const subClassRefp
+                                  = VN_CAST(subDtypep, ClassRefDType);
+                              if (!subClassRefp) return;
+                              addSubObjEnumConstraints(subClassRefp->classp(), smtName);
+                          });
+                      };
+                nodep->foreachMember([&](AstClass*, AstVar* memberVarp) {
+                    // Direct enum members
+                    if (memberVarp->user3()) {
+                        AstEnumDType* const enumDtp
+                            = VN_CAST(memberVarp->dtypep()->skipRefToEnump(), EnumDType);
+                        if (enumDtp) emitEnumConstraint(memberVarp->name(), enumDtp);
+                    }
+                    // Enum members inside globalConstrained sub-objects
+                    if (memberVarp->globalConstrained()) {
+                        const AstNodeDType* const dtypep = memberVarp->dtypep()->skipRefp();
+                        const AstClassRefDType* const classRefp = VN_CAST(dtypep, ClassRefDType);
+                        if (!classRefp) return;
+                        addSubObjEnumConstraints(classRefp->classp(), memberVarp->name());
+                    }
                 });
             }
 

test_regress/t/t_randomize_subobj_enum.py

@@ -0,0 +1,21 @@
+#!/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')
+
+if not test.have_solver:
+    test.skip("No constraint solver installed")
+
+test.compile()
+
+test.execute()
+
+test.passes()

test_regress/t/t_randomize_subobj_enum.v

@@ -0,0 +1,93 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain.
+// SPDX-FileCopyrightText: 2026 PlanV GmbH
+// 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\n", `__FILE__,`__LINE__, (gotv), (expv)); `stop; end while(0);
+// verilog_format: on
+
+// Check that an enum value is one of the valid members
+`define check_enum_color(gotv) \
+  if ((gotv) !== RED && (gotv) !== GREEN && (gotv) !== BLUE) begin \
+    $write("%%Error: %s:%0d: invalid color=%0d\n", `__FILE__, `__LINE__, (gotv)); \
+    `stop; \
+  end
+
+`define check_enum_state(gotv) \
+  if ((gotv) !== IDLE && (gotv) !== RUN && (gotv) !== STOP) begin \
+    $write("%%Error: %s:%0d: invalid state=%0d\n", `__FILE__, `__LINE__, (gotv)); \
+    `stop; \
+  end
+
+module t;
+
+  typedef enum logic [1:0] {
+    RED   = 2'd0,
+    GREEN = 2'd1,
+    BLUE  = 2'd2
+  } color_e;
+
+  typedef enum logic [2:0] {
+    IDLE  = 3'd0,
+    RUN   = 3'd3,
+    STOP  = 3'd5
+  } state_e;
+
+  class InnerObj;
+    rand color_e color;
+    rand state_e state;
+  endclass
+
+  class OuterObj;
+    rand InnerObj inner;
+
+    function new();
+      inner = new();
+    endfunction
+  endclass
+
+  // Nested: TopObj -> MiddleObj -> InnerObj
+  class MiddleObj;
+    rand InnerObj inner;
+
+    function new();
+      inner = new();
+    endfunction
+  endclass
+
+  class TopObj;
+    rand MiddleObj mid;
+
+    function new();
+      mid = new();
+    endfunction
+  endclass
+
+  initial begin
+    OuterObj obj;
+    TopObj top;
+    obj = new();
+    top = new();
+
+    // Test direct sub-object enum (one level deep)
+    repeat (20) begin
+      `checkd(obj.randomize(), 1)
+      `check_enum_color(obj.inner.color)
+      `check_enum_state(obj.inner.state)
+    end
+
+    // Test nested sub-object enum (two levels deep)
+    repeat (20) begin
+      `checkd(top.randomize(), 1)
+      `check_enum_color(top.mid.inner.color)
+      `check_enum_state(top.mid.inner.state)
+    end
+
+    $write("*-* All Finished *-*\n");
+    $finish;
+  end
+
+endmodule