Support `foreach` with nested dots (#6991)

Signed-off-by: Krzysztof Bieganski <kbieganski@antmicro.com>

src/V3LinkDot.cpp

@@ -1851,11 +1851,15 @@ class LinkDotFindVisitor final : public VNVisitor {
             m_curSymp->fallbackp(VL_RESTORER_PREV(m_curSymp));
             // DOT(x, SELLOOPVARS(var, loops)) -> SELLOOPVARS(DOT(x, var), loops)
             if (AstDot* const dotp = VN_CAST(nodep->arrayp(), Dot)) {
-                if (AstSelLoopVars* const loopvarsp = VN_CAST(dotp->rhsp(), SelLoopVars)) {
+                AstDot* dotAbovep = dotp;
+                while (AstDot* const dotNextp = VN_CAST(dotAbovep->rhsp(), Dot)) {
+                    dotAbovep = dotNextp;
+                }
+                if (AstSelLoopVars* const loopvarsp = VN_CAST(dotAbovep->rhsp(), SelLoopVars)) {
                     AstNodeExpr* const fromp = loopvarsp->fromp()->unlinkFrBack();
                     loopvarsp->unlinkFrBack();
                     dotp->replaceWith(loopvarsp);
-                    dotp->rhsp(fromp);
+                    dotAbovep->rhsp(fromp);
                     loopvarsp->fromp(dotp);
                 }
             }

test_regress/t/t_foreach_nested.py

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

test_regress/t/t_foreach_nested.v

@@ -0,0 +1,31 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain.
+// SPDX-FileCopyrightText: 2026 Antmicro
+// SPDX-License-Identifier: CC0-1.0
+
+typedef struct {
+  int x[9][9];
+} Foo;
+
+class Bar;
+  Foo foo;
+
+  function automatic void test();
+    foreach(this.foo.x[i])
+      foreach(this.foo.x[i][j])
+        this.foo.x[i][j] = i * j;
+    for (int i = 0; i < 9; i++)
+      for (int j = 0; j < 9; j++)
+        if (this.foo.x[i][j] != i * j) $stop;
+  endfunction
+endclass
+
+module t;
+  initial begin
+    Bar b = new;
+    b.test;
+    $write("*-* All Finished *-*\n");
+    $finish;
+  end
+endmodule