Unordered: Fix using a C++03 allocator with C++11 compiler.

Because the nodes had an implicit constructor, the `has_construct` traits was
detecting that the nodes could be constructed by construction then copy, which
really wasn't wanted. Also add a check that nodes aren't been copy constructed
to make sure this doesn't happen again. Refs #7100.

[SVN r79358]

include/boost/unordered/detail/equivalent.hpp

@@ -37,7 +37,7 @@ namespace boost { namespace unordered { namespace detail {
 
 #if BOOST_UNORDERED_DETAIL_FULL_CONSTRUCT
         template <BOOST_UNORDERED_EMPLACE_TEMPLATE>
-        grouped_node(BOOST_UNORDERED_EMPLACE_ARGS) :
+        explicit grouped_node(BOOST_UNORDERED_EMPLACE_ARGS) :
             node_base(),
             group_prev_(),
             hash_(0)
@@ -49,6 +49,10 @@ namespace boost { namespace unordered { namespace detail {
         ~grouped_node() {
             boost::unordered::detail::destroy(this->value_ptr());
         }
+
+        grouped_node(grouped_node const&) {
+            assert(false);
+        }
 #else
         grouped_node() :
             node_base(),
@@ -61,6 +65,9 @@ namespace boost { namespace unordered { namespace detail {
         {
             group_prev_ = self;
         }
+
+    private:
+        grouped_node& operator=(grouped_node const&);
     };
 
     template <typename T>
@@ -77,7 +84,7 @@ namespace boost { namespace unordered { namespace detail {
 
 #if BOOST_UNORDERED_DETAIL_FULL_CONSTRUCT
         template <BOOST_UNORDERED_EMPLACE_TEMPLATE>
-        grouped_ptr_node(BOOST_UNORDERED_EMPLACE_ARGS) :
+        explicit grouped_ptr_node(BOOST_UNORDERED_EMPLACE_ARGS) :
             bucket_base(),
             group_prev_(0),
             hash_(0)
@@ -89,6 +96,10 @@ namespace boost { namespace unordered { namespace detail {
         ~grouped_ptr_node() {
             boost::unordered::detail::destroy(this->value_ptr());
         }
+
+        grouped_ptr_node(grouped_ptr_node const&) {
+            assert(false);
+        }
 #else
         grouped_ptr_node() :
             bucket_base(),
@@ -101,6 +112,9 @@ namespace boost { namespace unordered { namespace detail {
         {
             group_prev_ = self;
         }
+
+    private:
+        grouped_ptr_node& operator=(grouped_ptr_node const&);
     };
 
     // If the allocator uses raw pointers use grouped_ptr_node