From f8968ab022ca1ac055b7643ee0f8498928dd1dad Mon Sep 17 00:00:00 2001
From: Daniel James <daniel@calamity.org.uk>
Date: Sat, 25 Aug 2012 21:54:18 +0000
Subject: [PATCH] Unordered: Better swap assertion.

[SVN r80224]
---
 include/boost/unordered/detail/table.hpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/boost/unordered/detail/table.hpp b/include/boost/unordered/detail/table.hpp
index cbf62195..116c4e9c 100644
--- a/include/boost/unordered/detail/table.hpp
+++ b/include/boost/unordered/detail/table.hpp
@@ -310,6 +310,11 @@ namespace boost { namespace unordered { namespace detail {
         template <typename Propagate>
         void swap(table& x, Propagate p)
         {
+            // According to 23.2.1.8, if propagate_on_container_swap is
+            // false the behaviour is undefined unless the allocators
+            // are equal.
+            BOOST_ASSERT(p.value || this->node_alloc() == x.node_alloc());
+
             boost::unordered::detail::set_hash_functions<hasher, key_equal>
                 op1(*this, x);
             boost::unordered::detail::set_hash_functions<hasher, key_equal>