From cd6b96276be613f2d313873046f92389a78c327e Mon Sep 17 00:00:00 2001
From: gabewillen <gabewillen@gmail.com>
Date: Mon, 23 Feb 2026 17:15:12 -0600
Subject: [PATCH] Fix issue #171 wildcard event double invocation

---
 include/boost/sml.hpp  |  2 ++
 test/ft/CMakeLists.txt |  3 +++
 test/ft/issue_171.cpp  | 44 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+)
 create mode 100644 test/ft/issue_171.cpp

diff --git a/include/boost/sml.hpp b/include/boost/sml.hpp
index 7065e66e..ddb0e191 100644
--- a/include/boost/sml.hpp
+++ b/include/boost/sml.hpp
@@ -1477,6 +1477,8 @@ struct get_event_mapping_impl_helper<on_entry<T1, T2>, TMappings>
 template <class T1, class T2, class TMappings>
 struct get_event_mapping_impl_helper<on_exit<T1, T2>, TMappings>
     : decltype(get_event_mapping_impl<on_exit<T1, T2>>((TMappings *)0)) {};
+template <class TMappings>
+struct get_event_mapping_impl_helper<anonymous, TMappings> : decltype(get_event_mapping_impl<anonymous>((TMappings *)0)) {};
 template <class T, class TMappings>
 using get_event_mapping_t = get_event_mapping_impl_helper<T, TMappings>;
 }  // namespace back
diff --git a/test/ft/CMakeLists.txt b/test/ft/CMakeLists.txt
index 6c1750b9..feaf4d43 100644
--- a/test/ft/CMakeLists.txt
+++ b/test/ft/CMakeLists.txt
@@ -48,6 +48,9 @@ add_test(test_fwd test_fwd)
 add_executable(test_history history.cpp)
 add_test(test_history test_history)
 
+add_executable(test_issue_171 issue_171.cpp)
+add_test(test_issue_171 test_issue_171)
+
 add_executable(test_issue_253 issue_253.cpp)
 add_test(test_issue_253 test_issue_253)
 
diff --git a/test/ft/issue_171.cpp b/test/ft/issue_171.cpp
new file mode 100644
index 00000000..52abe7f9
--- /dev/null
+++ b/test/ft/issue_171.cpp
@@ -0,0 +1,44 @@
+//
+// Copyright (c) 2016-2020 Kris Jusiak (kris at jusiak dot net)
+//
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+#include <boost/sml.hpp>
+
+namespace sml = boost::sml;
+
+test issue_171_event_any_is_not_fired_twice = [] {
+  struct e1 {};
+
+  struct issue_171_counters {
+    int init_calls = 0;
+    int wildcard_calls = 0;
+  };
+
+  struct issue_171_transitions {
+    auto operator()() const noexcept {
+      using namespace sml;
+      const auto issue_171_idle = sml::state<class issue_171_idle>;
+      const auto issue_171_s1 = sml::state<class issue_171_s1>;
+      const auto issue_171_s2 = sml::state<class issue_171_s2>;
+
+      // clang-format off
+      return make_transition_table(
+          *issue_171_idle / [](issue_171_counters& counters) { ++counters.init_calls; } = issue_171_s1
+        , issue_171_s1 + event<_> / [](issue_171_counters& counters) { ++counters.wildcard_calls; }
+        , issue_171_s2 + event<e1> / [] {}
+      );
+      // clang-format on
+    }
+  };
+
+  issue_171_counters counters{};
+  sml::sm<issue_171_transitions> sm{counters};
+
+  sm.process_event(e1{});
+
+  expect(1 == counters.init_calls);
+  expect(1 == counters.wildcard_calls);
+};