add an unsup test for case 'one var but in two different global constraints'

src/V3Randomize.cpp

@@ -236,14 +236,27 @@ class RandomizeMarkVisitor final : public VNVisitor {
     // Process a single constraint during nested constraint cloning
     void processNestedConstraint(AstConstraint* const constrp, AstVarRef* rootVarRefp,
                                  const std::vector<AstVar*>& newPath) {
-        AstConstraint* const cloneConstrp = constrp->cloneTree(false);
-
         std::string pathPrefix = rootVarRefp->name();
         for (AstVar* pathMemberVarp : newPath) {
             pathPrefix += GLOBAL_CONSTRAINT_SEPARATOR + pathMemberVarp->name();
         }
 
-        cloneConstrp->name(pathPrefix + GLOBAL_CONSTRAINT_SEPARATOR + cloneConstrp->name());
+        const std::string newName = pathPrefix + GLOBAL_CONSTRAINT_SEPARATOR + constrp->name();
+
+        for (const AstConstraint* existingConstrp : m_clonedConstraints) {
+            if (existingConstrp->name() == newName) {
+                // Multiple paths lead to same constraint - unsupported pattern
+                std::string fullPath = rootVarRefp->name();
+                for (AstVar* pathVar : newPath) { fullPath += "." + pathVar->name(); }
+                constrp->v3warn(E_UNSUPPORTED, "Unsupported: One variable '"
+                                                   << fullPath
+                                                   << "' cannot have multiple global constraints");
+                return;
+            }
+        }
+
+        AstConstraint* const cloneConstrp = constrp->cloneTree(false);
+        cloneConstrp->name(newName);
         cloneConstrp->foreach([&](AstVarRef* varRefp) {
             AstNodeExpr* const chainp = buildMemberSelChain(rootVarRefp, newPath);
             AstMemberSel* const finalSelp

test_regress/t/t_constraint_global_nested_unsup.out

@@ -0,0 +1,6 @@
+%Error-UNSUPPORTED: t/t_constraint_global_nested_unsup.v:9:14: Unsupported: Variable 'm_mid.m_inner' cannot have multiple global constraints
+                                                             : ... note: In instance 't'
+    9 |   constraint c_inner { m_val inside {[1:10]}; }
+      |              ^~~~~~~
+                    ... For error description see https://verilator.org/warn/UNSUPPORTED?v=latest
+%Error: Exiting due to

test_regress/t/t_constraint_global_nested_unsup.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2024 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('vlt')
+
+test.lint(fails=test.vlt_all, expect_filename=test.golden_filename)
+
+test.passes()

test_regress/t/t_constraint_global_nested_unsup.v

@@ -0,0 +1,51 @@
+// DESCRIPTION: Verilator: Test for unsupported multiple global constraints
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by PlanV GmbH.
+// SPDX-License-Identifier: CC0-1.0
+
+
+class Inner;
+  rand int m_val;
+  constraint c_inner { m_val inside {[1:10]}; }
+  function new(); m_val = 0; endfunction
+endclass
+
+class Mid;
+  rand Inner m_inner;
+  rand int m_x;
+  // Mid has global constraint on m_inner.m_val
+  constraint c_mid_global {
+    m_x > m_inner.m_val;
+    m_x inside {[5:15]};
+  }
+  function new();
+    m_inner = new();
+    m_x = 0;
+  endfunction
+endclass
+
+class Top;
+  rand Mid m_mid;
+  rand int m_y;
+  // Top also has global constraint on m_mid.m_inner.m_val
+  constraint c_top_global {
+    m_y < m_mid.m_inner.m_val;
+    m_y inside {[1:5]};
+  }
+  function new();
+    m_mid = new();
+    m_y = 0;
+  endfunction
+endclass
+
+module t;
+  Top top;
+  /* verilator lint_off WIDTHTRUNC */
+  initial begin
+    top = new();
+    if (!top.randomize()) $stop;
+    $write("*-* All Finished *-*\n");
+    $finish;
+  end
+  /* verilator lint_off WIDTHTRUNC */
+endmodule