Fix recursive constant function in $unit scope (V3Scope.cpp:359) (#7174)

docs/CONTRIBUTORS

@@ -99,6 +99,7 @@ Ivan Vnučec
 Iztok Jeras
 Jake Merdich
 Jakub Wasilewski
+jalcim
 James Bailey
 James Hanlon
 James Hutchinson

src/V3Scope.cpp

@@ -259,6 +259,7 @@ class ScopeVisitor final : public VNVisitor {
             clonep = nodep->cloneTree(false);
         }
         nodep->user2p(clonep);
+        clonep->user2p(clonep);  // For recursive self-references after cloneTree
         m_scopep->addBlocksp(clonep);
         // We iterate under the *clone*
         iterateChildren(clonep);

test_regress/t/t_func_unit_recursive.py

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

@@ -0,0 +1,38 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2026 by jalcim.
+// SPDX-License-Identifier: CC0-1.0
+
+// Recursive constant function defined at file scope ($unit).
+// Without the V3Scope.cpp fix, this triggers:
+//   %Error: Internal Error: V3Scope.cpp: No clone for package function
+
+function automatic integer gate_depth;
+  input integer way;
+  integer d1, d2, sc, n1, n2;
+  begin
+    if (way <= 1) gate_depth = 0;
+    else if (way <= 4) gate_depth = 1;
+    else begin
+      sc = $clog2(way);
+      n1 = 1 << (sc - 1);
+      n2 = way - n1;
+      d1 = gate_depth(n1);
+      d2 = gate_depth(n2);
+      gate_depth = ((d1 > d2) ? d1 : d2) + 1;
+    end
+  end
+endfunction
+
+module t;
+  localparam D5 = gate_depth(5);
+  localparam D8 = gate_depth(8);
+
+  initial begin
+    if (D5 !== 2) $stop;
+    if (D8 !== 2) $stop;
+    $write("*-* All Finished *-*\n");
+    $finish;
+  end
+endmodule