Add error on too many pattern members for structure

src/V3Width.cpp

@@ -4680,17 +4680,17 @@ class WidthVisitor final : public VNVisitor {
                                 "Assignment pattern key not supported/understood: "
                                 << patp->keyp()->prettyTypeName());
                         }
-                    } else {
+                    } else if (memp) {
                         // constant expr
-                        if (memp) {
-                            const std::pair<PatMap::iterator, bool> ret
-                                = patmap.emplace(memp, patp);
-                            if (!ret.second) {
-                                patp->v3error("Assignment pattern contains duplicate entry: "
-                                              << VN_AS(patp->keyp(), Text)->text());
-                            }
-                            memp = VN_AS(memp->nextp(), MemberDType);
+                        const std::pair<PatMap::iterator, bool> ret = patmap.emplace(memp, patp);
+                        if (!ret.second) {
+                            patp->v3error("Assignment pattern contains duplicate entry: "
+                                          << VN_AS(patp->keyp(), Text)->text());
                         }
+                        memp = VN_AS(memp->nextp(), MemberDType);
+                    } else {
+                        patp->v3error(
+                            "Assignment pattern contains more entries than structure members");
                     }
                 } while (false);
 

test_regress/t/t_struct_pat_toomany_bad.out

@@ -0,0 +1,6 @@
+%Error: t/t_struct_pat_toomany_bad.v:12:18: Assignment pattern contains more entries than structure members
+                                          : ... note: In instance 't'
+   12 |   } sp = '{1, 2, 3};   
+      |                  ^
+        ... See the manual at https://verilator.org/verilator_doc.html?v=latest for more assistance.
+%Error: Exiting due to

test_regress/t/t_struct_pat_toomany_bad.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('linter')
+
+test.lint(fails=True, expect_filename=test.golden_filename)
+
+test.passes()

test_regress/t/t_struct_pat_toomany_bad.v

@@ -0,0 +1,18 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2025 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+module t;
+
+  struct packed {
+    int m_i;
+    byte m_b;
+  } sp = '{1, 2, 3};  // BAD, too many elements
+
+  initial begin
+    $display("FAILED");
+  end
+
+endmodule