From 09ca7ea8d1f0f1048eabffe276e8f1b9bf4ae0e3 Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Mon, 12 Jan 2026 22:56:23 -0500
Subject: [PATCH] Fix emitting unbounded parameters (#6912).

Fixes #6912.
---
 Changes                      |  1 +
 src/V3EmitCConstInit.h       |  5 +++++
 test_regress/t/t_unbounded.v | 28 ++++++++++++++--------------
 3 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/Changes b/Changes
index 3f93dc295..0b64e4dfb 100644
--- a/Changes
+++ b/Changes
@@ -389,6 +389,7 @@ Verilator 5.040 2025-08-30
 * Fix wide select expansion and substitution (#6341) (#6345). [Geza Lore]
 * Fix upcasting class type parameters (#6344). [Krzysztof Bieganski, Antmicro Ltd.]
 * Fix undefined weak link for Apple GCC etc (#6348). [Congcong Cai]
+* Fix emitting unbounded parameters (#6912).
 * Fix syntax error on unsupported defparam array (#6915).
 
 
diff --git a/src/V3EmitCConstInit.h b/src/V3EmitCConstInit.h
index ab88a5332..59427cfb5 100644
--- a/src/V3EmitCConstInit.h
+++ b/src/V3EmitCConstInit.h
@@ -99,6 +99,11 @@ protected:
         UASSERT_OBJ(!num.isFourState(), nodep, "4-state value in constant pool");
         putns(nodep, num.emitC());
     }
+    void visit(AstUnbounded* nodep) override {
+        // e.g. when emitting a public parameter's "$" value
+        // But Unbounded is only special during elaboration, so just use zero
+        putns(nodep, "0");
+    }
 
     // Default
     void visit(AstNode* nodep) override {  // LCOV_EXCL_START
diff --git a/test_regress/t/t_unbounded.v b/test_regress/t/t_unbounded.v
index a8b6d3bba..4d61f8872 100644
--- a/test_regress/t/t_unbounded.v
+++ b/test_regress/t/t_unbounded.v
@@ -4,20 +4,20 @@
 // any use, without warranty, 2014 by Wilson Snyder.
 // SPDX-License-Identifier: CC0-1.0
 
-module t();
+module t;
 
-   localparam UNB = $;
-   localparam int UNB2 = $;
-   localparam SIX = 6;
+  parameter int UNB /*verilator public*/ = $;
+  localparam int UNB2 = $;
+  localparam SIX = 6;
 
-   initial begin
-      if ($bits($isunbounded(0)) !== 1) $stop;
-      if ($isunbounded(0) !== 1'b0) $stop;
-      if ($isunbounded(SIX) !== 0) $stop;
-      if ($isunbounded($) !== 1) $stop;
-      if ($isunbounded(UNB) !== 1) $stop;
-      if ($isunbounded(UNB2) !== 1) $stop;
-      $write("*-* All Finished *-*\n");
-      $finish;
-   end
+  initial begin
+    if ($bits($isunbounded(0)) !== 1) $stop;
+    if ($isunbounded(0) !== 1'b0) $stop;
+    if ($isunbounded(SIX) !== 0) $stop;
+    if ($isunbounded($) !== 1) $stop;
+    if ($isunbounded(UNB) !== 1) $stop;
+    if ($isunbounded(UNB2) !== 1) $stop;
+    $write("*-* All Finished *-*\n");
+    $finish;
+  end
 endmodule