Fix references to interfaces containing generate blocks (#6579)

src/V3LinkDot.cpp

@@ -3597,10 +3597,17 @@ class LinkDotResolveVisitor final : public VNVisitor {
                         m_ds.m_dotSymp = foundp;
                         m_ds.m_dotPos = DP_SCOPE;
                         UINFO(9, indent() << " cell -> iface varref " << foundp->nodep());
-                        AstNodeVarRef* newp;
+                        AstNodeExpr* newp;
                         if (m_ds.m_dotText != "") {
                             newp = new AstVarXRef{nodep->fileline(), ifaceRefVarp, m_ds.m_dotText,
                                                   VAccess::READ};
+                            if (m_ds.m_unresolvedCell && m_ds.m_unlinkedScopep) {
+                                newp = new AstUnlinkedRef{nodep->fileline(), newp, newp->name(),
+                                                          m_ds.m_unlinkedScopep->unlinkFrBack()};
+                                m_ds.m_unlinkedScopep = nullptr;
+                                m_ds.m_unresolvedCell = false;
+                                m_ds.m_dotText = "";
+                            }
                         } else {
                             newp = new AstVarRef{nodep->fileline(), ifaceRefVarp, VAccess::READ};
                         }

test_regress/t/t_virtual_interface_gen_for_ref.py

@@ -0,0 +1,18 @@
+#!/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('simulator')
+
+test.compile()
+
+test.execute()
+
+test.passes()

test_regress/t/t_virtual_interface_gen_for_ref.v

@@ -0,0 +1,82 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by Antmicro.
+// SPDX-License-Identifier: CC0-1.0
+
+package uvm_pkg;
+  class uvm_resource_db #(
+      type T = int
+  );
+    static T interf;
+
+    static function void set(input T accessor);
+      interf = accessor;
+    endfunction
+  endclass
+
+  class uvm_config_db #(
+      type T = int
+  ) extends uvm_resource_db #(T);
+  endclass
+endpackage
+
+
+interface iface ();
+  int x = 1;
+endinterface
+
+module t;
+  import uvm_pkg::*;
+
+  bind bound iface if_bind ();
+  dut i_dut ();
+
+  initial begin
+    uvm_config_db#(virtual iface)::set(
+        t.i_dut.first_gen[0].i_fail.i_a.i_b.i_c.second_gen[0].i_d.i_bound.if_bind);
+
+    if (uvm_config_db#(virtual iface)::interf.x != 1) $stop;
+
+    $write("*-* All Finished *-*\n");
+    $finish;
+  end
+endmodule
+
+module bound ();
+endmodule
+
+module dut ();
+  genvar g_core;
+  generate
+    for (g_core = 0; g_core < 1; g_core++) begin : first_gen
+      fail_mod i_fail ();
+    end
+  endgenerate
+endmodule
+
+module fail_mod ();
+  a i_a ();
+endmodule
+
+module a ();
+  b i_b ();
+endmodule
+;
+
+module b ();
+  c i_c ();
+endmodule
+
+module c ();
+  genvar gi;
+  generate
+    for (gi = 0; gi < 1; gi++) begin : second_gen
+      d i_d ();
+    end
+  endgenerate
+endmodule
+
+module d ();
+  bound i_bound ();
+endmodule