added reentrancy checking

test/Jamfile.v2

@@ -202,6 +202,7 @@ local CFOA_TESTS =
   rw_spinlock_test6
   rw_spinlock_test7
   rw_spinlock_test8
+  reentrancy_check_test
 ;
 
 for local test in $(CFOA_TESTS)

test/cfoa/reentrancy_check_test.cpp

@@ -0,0 +1,68 @@
+// Copyright 2023 Joaquin M Lopez Munoz
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#define BOOST_UNORDERED_ENABLE_REENTRANCY_CHECK_HANDLER
+
+static bool reentrancy_detected = false;
+
+namespace boost {
+  // Caveat lector: a proper handler should terminate as it may be executed
+  // within a noexcept function.
+
+  void boost_unordered_reentrancy_check_failed()
+  {
+    reentrancy_detected = true;
+    throw 0;
+  }
+}
+
+#include <boost/unordered/concurrent_flat_map.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+template<typename F>
+void detect_reentrancy(F f)
+{
+  reentrancy_detected = false;
+  try {
+    f();
+  }
+  catch(int) {}
+  BOOST_TEST(reentrancy_detected);
+}
+
+int main()
+{
+  using map = boost::concurrent_flat_map<int, int>;
+  using value_type = typename map::value_type;
+
+  map m1, m2;
+  m1.emplace(0, 0);
+  m2.emplace(1, 0);
+
+  detect_reentrancy([&] {
+    m1.visit_all([&](value_type&) { (void)m1.contains(0); });
+  });
+
+  detect_reentrancy([&] {
+    m1.visit_all([&](value_type&) { m1.rehash(0); });
+  });
+
+  detect_reentrancy([&] {
+    m1.visit_all([&](value_type&) { 
+      m2.visit_all([&](value_type&) { 
+        m1=m2;
+      });
+    });
+  });
+
+  detect_reentrancy([&] {
+    m1.visit_all([&](value_type&) { 
+      m2.visit_all([&](value_type&) { 
+        m2=m1;
+      });
+    });
+  });
+
+  return boost::report_errors();
+}