Fix static call after covergroup (#6916 repair)

src/V3Ast.cpp

@@ -139,6 +139,13 @@ AstNode* AstNode::abovep() const {
     const AstNode* const firstp = firstAbovep() ? this : m_headtailp;
     return firstp->backp();
 }
+AstNode* AstNode::aboveLoopp() const {
+    // Returns parent node. Avoid using this, may have performance issues.
+    const AstNode* nodep = this;
+    // Backwards over peers (versus parents)
+    while (nodep->backp() && nodep->backp()->nextp() == nodep) nodep = nodep->backp();
+    return nodep->backp();
+}
 
 string AstNode::encodeName(const string& namein) {
     // Encode signal name raw from parser, then not called again on same signal

src/V3Ast.h

@@ -540,6 +540,7 @@ public:
     AstNode* nextp() const VL_MT_STABLE { return m_nextp; }
     AstNode* backp() const VL_MT_STABLE { return m_backp; }
     AstNode* abovep() const;  // Get parent node above, only for list head and tail
+    AstNode* aboveLoopp() const;  // Get parent node above, may have performance issues as loops
     AstNode* op1p() const VL_MT_STABLE { return m_op1p; }
     AstNode* op2p() const VL_MT_STABLE { return m_op2p; }
     AstNode* op3p() const VL_MT_STABLE { return m_op3p; }

src/V3Width.cpp

@@ -6654,7 +6654,7 @@ class WidthVisitor final : public VNVisitor {
         return VN_CAST(pkgItemp->backp(), Package);
     }
     const AstClass* containingClass(AstNode* nodep) {
-        // backp is still needed, m_containingClassp is just a cache
+        // abovep is still needed, m_containingClassp is just a cache
         if (const AstClass* const classp = VN_CAST(nodep, Class))
             return m_containingClassp[nodep] = classp;
         if (const AstClassPackage* const packagep = VN_CAST(nodep, ClassPackage)) {
@@ -6663,8 +6663,8 @@ class WidthVisitor final : public VNVisitor {
         if (m_containingClassp.find(nodep) != m_containingClassp.end()) {
             return m_containingClassp[nodep];
         }
-        if (nodep->backp()) {
-            return m_containingClassp[nodep] = containingClass(nodep->backp());
+        if (AstNode* const abovep = nodep->aboveLoopp()) {
+            return m_containingClassp[nodep] = containingClass(abovep);
         } else {
             return m_containingClassp[nodep] = nullptr;
         }

test_regress/t/t_class_static_after_cg.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2025 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.lint()
+
+test.passes()

test_regress/t/t_class_static_after_cg.v

@@ -0,0 +1,27 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2026 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+module t;
+  class Cls;
+    // verilator lint_off COVERIGN
+    covergroup cov_trans;
+      option.per_instance = 1;
+    endgroup
+
+    virtual function void perform_transfer_checks();
+      check_transfer_size();
+    endfunction
+    virtual function void check_transfer_size();
+    endfunction
+  endclass
+
+  initial begin
+    Cls c;
+    c = new;
+    c.perform_transfer_checks();
+    $finish;
+  end
+endmodule