From a8f62703ab094e4f577a8bd0de8531a9a87adc9c Mon Sep 17 00:00:00 2001
From: Nikolay Puzanov <np@embddr.xyz>
Date: Fri, 10 Apr 2026 19:17:06 +0300
Subject: [PATCH] Fix virtual class inheritance (#7403) (#7405)

Fixes #7403.
---
 docs/CONTRIBUTORS                             |  1 +
 src/V3LinkDot.cpp                             |  2 +-
 .../t/t_class_virtual_extends_pure.py         | 16 +++++++++++++
 test_regress/t/t_class_virtual_extends_pure.v | 23 +++++++++++++++++++
 4 files changed, 41 insertions(+), 1 deletion(-)
 create mode 100644 test_regress/t/t_class_virtual_extends_pure.py
 create mode 100644 test_regress/t/t_class_virtual_extends_pure.v

diff --git a/docs/CONTRIBUTORS b/docs/CONTRIBUTORS
index b5a99ea6c..d4ed0f96f 100644
--- a/docs/CONTRIBUTORS
+++ b/docs/CONTRIBUTORS
@@ -197,6 +197,7 @@ Nathan Graybeal
 Nathan Kohagen
 Nathan Myers
 Nick Brereton
+Nikolay Puzanov
 Nolan Poe
 Oleh Maksymenko
 Patrick Stewart
diff --git a/src/V3LinkDot.cpp b/src/V3LinkDot.cpp
index c9174bcce..5054de9dd 100644
--- a/src/V3LinkDot.cpp
+++ b/src/V3LinkDot.cpp
@@ -3406,7 +3406,7 @@ class LinkDotResolveVisitor final : public VNVisitor {
                     if (!baseFuncp || !baseFuncp->pureVirtual()) continue;
                     const bool existsInDerived = foundp && !foundp->imported();
                     if (m_statep->forPrimary() && !existsInDerived
-                        && !derivedClassp->isInterfaceClass()) {
+                        && !derivedClassp->isInterfaceClass() && !derivedClassp->isVirtual()) {
                         derivedClassp->v3error(
                             "Class " << derivedClassp->prettyNameQ() << impOrExtends
                                      << baseClassp->prettyNameQ()
diff --git a/test_regress/t/t_class_virtual_extends_pure.py b/test_regress/t/t_class_virtual_extends_pure.py
new file mode 100644
index 000000000..363cbe649
--- /dev/null
+++ b/test_regress/t/t_class_virtual_extends_pure.py
@@ -0,0 +1,16 @@
+#!/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('vlt')
+
+test.lint()
+
+test.passes()
diff --git a/test_regress/t/t_class_virtual_extends_pure.v b/test_regress/t/t_class_virtual_extends_pure.v
new file mode 100644
index 000000000..7619aa264
--- /dev/null
+++ b/test_regress/t/t_class_virtual_extends_pure.v
@@ -0,0 +1,23 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain.
+// SPDX-FileCopyrightText: 2026 Wilson Snyder
+// SPDX-License-Identifier: CC0-1.0
+
+virtual class Base;
+  pure virtual function void f0();
+endclass
+
+virtual class Child extends Base;
+  pure virtual function void f1();
+endclass
+
+class Impl extends Child;
+  virtual function void f0();
+  endfunction
+  virtual function void f1();
+  endfunction
+endclass
+
+module t;
+endmodule