From 752b77ea778587710a742d571c2dcf9665f58d2b Mon Sep 17 00:00:00 2001
From: Todd Strader <todd.strader@gmail.com>
Date: Thu, 7 May 2026 17:02:41 -0400
Subject: [PATCH] Fix events in observed region (#7546)

---
 src/V3Active.cpp                         | 14 +++++++++++++
 test_regress/t/t_clocking_event_sense.py | 18 +++++++++++++++++
 test_regress/t/t_clocking_event_sense.v  | 25 ++++++++++++++++++++++++
 3 files changed, 57 insertions(+)
 create mode 100755 test_regress/t/t_clocking_event_sense.py
 create mode 100644 test_regress/t/t_clocking_event_sense.v

diff --git a/src/V3Active.cpp b/src/V3Active.cpp
index c8122c2c4..846183f4c 100644
--- a/src/V3Active.cpp
+++ b/src/V3Active.cpp
@@ -486,6 +486,18 @@ class ActiveVisitor final : public VNVisitor {
         }
     }
 
+    static void markEventEdges(AstSenTree* sentreep) {
+        for (AstSenItem* senip = sentreep->sensesp(); senip;
+             senip = VN_AS(senip->nextp(), SenItem)) {
+            if (!senip->sensp()) continue;
+            if (const AstNodeDType* const dtypep = senip->sensp()->dtypep()) {
+                if (const AstBasicDType* const basicp = dtypep->basicp()) {
+                    if (basicp->isEvent()) senip->edgeType(VEdgeType::ET_EVENT);
+                }
+            }
+        }
+    }
+
     // VISITORS
     void visit(AstScope* nodep) override {
         m_namer.main(nodep);  // Clear last scope's names, and collect this scope's existing names
@@ -528,6 +540,7 @@ class ActiveVisitor final : public VNVisitor {
     }
     void visit(AstAlwaysObserved* nodep) override {
         UASSERT_OBJ(nodep->sentreep(), nodep, "Should have a sentree");
+        markEventEdges(nodep->sentreep());
         AstSenTree* const sentreep = nodep->sentreep();
         sentreep->unlinkFrBack();
         // Make a new active for it, needs to be the only item under the active for V3Sched
@@ -536,6 +549,7 @@ class ActiveVisitor final : public VNVisitor {
     }
     void visit(AstAlwaysReactive* nodep) override {
         UASSERT_OBJ(nodep->sentreep(), nodep, "Should have a sentree");
+        markEventEdges(nodep->sentreep());
         AstSenTree* const sentreep = nodep->sentreep();
         sentreep->unlinkFrBack();
         // Make a new active for it, needs to be the only item under the active for V3Sched
diff --git a/test_regress/t/t_clocking_event_sense.py b/test_regress/t/t_clocking_event_sense.py
new file mode 100755
index 000000000..e6a0c4851
--- /dev/null
+++ b/test_regress/t/t_clocking_event_sense.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(verilator_flags2=["--binary"], make_main=False)
+
+test.execute()
+
+test.passes()
diff --git a/test_regress/t/t_clocking_event_sense.v b/test_regress/t/t_clocking_event_sense.v
new file mode 100644
index 000000000..57d850d3c
--- /dev/null
+++ b/test_regress/t/t_clocking_event_sense.v
@@ -0,0 +1,25 @@
+// 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
+
+`timescale 1ms / 1ns
+module t;
+  event e;
+  bit data = 0;
+
+  clocking cb @e;
+    input #0 data;
+  endclocking
+
+  initial begin
+    #1;
+    data = 1;
+    -> e;
+    #1;
+    if (cb.data !== 1'b1) $stop;
+    $write("*-* All Finished *-*\n");
+    $finish;
+  end
+endmodule