Add assertion on firing event inside class (#5597)

src/V3Delayed.cpp

@@ -891,6 +891,7 @@ class DelayedVisitor final : public VNVisitor {
                 ifp->addThensp(newp);
             }
 
+            UASSERT_OBJ(m_activep, nodep, "No active to handle FireEvent");
             AstActive* const activep = new AstActive{flp, "nba-event", m_activep->sensesp()};
             m_activep->addNextHere(activep);
             activep->addStmtsp(prep);

test_regress/t/t_event_class_fire.out

@@ -0,0 +1,5 @@
+%Error: Internal Error: t/t_event_class_fire.v:10:7: ../V3Delayed.cpp:#: No active to handle FireEvent
+                                                   : ... note: In instance '$unit::Cls'
+   10 |       ->> e;
+      |       ^~~
+                        ... See the manual at https://verilator.org/verilator_doc.html for more assistance.

test_regress/t/t_event_class_fire.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2024 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')
+
+# Issue #5597 makes this fail
+test.compile(fails=test.vlt_all,
+             expect_filename=test.golden_filename,
+             verilator_flags2=['--timing'])
+
+#test.execute()
+
+test.passes()

test_regress/t/t_event_class_fire.v

@@ -0,0 +1,24 @@
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed under the Creative Commons Public Domain, for
+// any use, without warranty, 2024 by Wilson Snyder.
+// SPDX-License-Identifier: CC0-1.0
+
+class Cls;
+   event e;
+   task trig_e();
+      ->> e;
+   endtask
+endclass
+
+module top();
+   event e;
+   initial begin
+      Cls c;
+      c = new;
+      c.trig_e();
+      wait(e.triggered);
+      $write("*-* All Finished *-*\n");
+      $finish;
+   end
+endmodule