diff --git a/doc/intrusive.qbk b/doc/intrusive.qbk
index 8f22132..cec74b5 100644
--- a/doc/intrusive.qbk
+++ b/doc/intrusive.qbk
@@ -1096,7 +1096,7 @@ And they also can receive an additional option:
 
 *  [*`compare<class Compare>`]: Comparison function for the objects to be inserted
    in containers. The comparison functor must induce a strict weak ordering.
-   Default: `compare< std::less<T> >`
+   Default: `compare< std::less<key_type> >`
 
 *  [*`key_of_value<class KeyOfValueFunctionObject>`]: A function object that will
    define the `key_type` of the value type to be stored. This type will allow a map-like interface. See
@@ -1512,7 +1512,7 @@ And they also can receive an additional option:
 
 *  [*`compare<class Compare>`]: Comparison function for the objects to be inserted
    in containers. The comparison functor must induce a strict weak ordering.
-   Default: `compare< std::less<T> >`
+   Default: `compare< std::less<key_type> >`
 
 *  [*`key_of_value<class KeyOfValueFunctionObject>`]: A function object that will
    define the `key_type` of the value type to be stored. This type will allow a map-like interface. See
@@ -1614,7 +1614,7 @@ And they also can receive an additional option:
 
 *  [*`compare<class Compare>`]: Comparison function for the objects to be inserted
    in containers. The comparison functor must induce a strict weak ordering.
-   Default: `compare< std::less<T> >`
+   Default: `compare< std::less<key_type> >`
 
 *  [*`key_of_value<class KeyOfValueFunctionObject>`]: A function object that will
    define the `key_type` of the value type to be stored. This type will allow a map-like interface. See
@@ -1725,7 +1725,7 @@ And they also can receive additional options:
 
 *  [*`compare<class Compare>`]: Comparison function for the objects to be inserted
    in containers. The comparison functor must induce a strict weak ordering.
-   Default: `compare< std::less<T> >`
+   Default: `compare< std::less<key_type> >`
 
 *  [*`floating_point<bool Enable>`]:
    When this option is deactivated, the scapegoat tree loses the ability to change
@@ -1828,11 +1828,11 @@ And they also can receive additional options:
 
 *  [*`compare<class Compare>`]: Comparison function for the objects to be inserted
    in containers. The comparison functor must induce a strict weak ordering.
-   Default: `compare< std::less<T> >`
+   Default: `compare< std::less<key_type> >`
 
 *  [*`priority<class PriorityCompare>`]: Priority Comparison function for the objects to be inserted
    in containers. The comparison functor must induce a strict weak ordering.
-   Default: `priority< priority_compare<T> >`
+   Default: `priority< priority_compare<key_type> >`
 
 *  [*`key_of_value<class KeyOfValueFunctionObject>`]: A function object that will
    define the `key_type` of the value type to be stored. This type will allow a map-like interface. See
@@ -3840,6 +3840,7 @@ to be inserted in intrusive containers are allocated using `std::vector` or `std
 *  Fixed bugs:
    *  [@https://svn.boost.org/trac/boost/ticket/11832 Boost Trac #11832: ['clang-cl + boost intrusive = miscompile]]
    *  [@https://svn.boost.org/trac/boost/ticket/11865 Boost Trac #11865: ['Intrusive list explicit ctor error with Clang 3.6 (C++11/14)]]
+   *  [@https://svn.boost.org/trac/boost/ticket/11992 Boost Trac #11992: ['Add an overload of insert_check taking a key_type]]
    *  [@https://github.com/boostorg/intrusive/pull/19 GitHub Pull #19: ['ebo_functor_holder: compile fix for copy constructor]]
 
 [endsect]
diff --git a/include/boost/intrusive/avl_set.hpp b/include/boost/intrusive/avl_set.hpp
index 8f7139a..2c96204 100644
--- a/include/boost/intrusive/avl_set.hpp
+++ b/include/boost/intrusive/avl_set.hpp
@@ -200,6 +200,17 @@ class avl_set_impl
    iterator insert(const_iterator hint, reference value)
    {  return tree_type::insert_unique(hint, value);  }
 
+   //! @copydoc ::boost::intrusive::avltree::insert_unique_check(const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_check
+      (const key_type &key, insert_commit_data &commit_data)
+   {  return tree_type::insert_unique_check(key, commit_data); }
+
+   //! @copydoc ::boost::intrusive::avltree::insert_unique_check(const_iterator,const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_check
+      (const_iterator hint, const key_type &key
+      ,insert_commit_data &commit_data)
+   {  return tree_type::insert_unique_check(hint, key, commit_data); }
+
    //! @copydoc ::boost::intrusive::avltree::insert_unique_check(const KeyType&,KeyTypeKeyCompare,insert_commit_data&)
    template<class KeyType, class KeyTypeKeyCompare>
    std::pair<iterator, bool> insert_check
@@ -325,21 +336,21 @@ class avl_set_impl
 
    #endif   //   #ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED
 
-   //! @copydoc ::boost::intrusive::rbtree::equal_range(const key_type &)
+   //! @copydoc ::boost::intrusive::avltree::equal_range(const key_type &)
    std::pair<iterator,iterator> equal_range(const key_type &key)
    {  return this->tree_type::lower_bound_range(key); }
 
-   //! @copydoc ::boost::intrusive::rbtree::equal_range(const KeyType&,KeyTypeKeyCompare)
+   //! @copydoc ::boost::intrusive::avltree::equal_range(const KeyType&,KeyTypeKeyCompare)
    template<class KeyType, class KeyTypeKeyCompare>
    std::pair<iterator,iterator> equal_range(const KeyType& key, KeyTypeKeyCompare comp)
    {  return this->tree_type::equal_range(key, comp); }
 
-   //! @copydoc ::boost::intrusive::rbtree::equal_range(const key_type &)const
+   //! @copydoc ::boost::intrusive::avltree::equal_range(const key_type &)const
    std::pair<const_iterator, const_iterator>
       equal_range(const key_type &key) const
    {  return this->tree_type::lower_bound_range(key); }
 
-   //! @copydoc ::boost::intrusive::rbtree::equal_range(const KeyType&,KeyTypeKeyCompare)const
+   //! @copydoc ::boost::intrusive::avltree::equal_range(const KeyType&,KeyTypeKeyCompare)const
    template<class KeyType, class KeyTypeKeyCompare>
    std::pair<const_iterator, const_iterator>
       equal_range(const KeyType& key, KeyTypeKeyCompare comp) const
diff --git a/include/boost/intrusive/avltree.hpp b/include/boost/intrusive/avltree.hpp
index 37e3859..741d482 100644
--- a/include/boost/intrusive/avltree.hpp
+++ b/include/boost/intrusive/avltree.hpp
@@ -260,6 +260,14 @@ class avltree_impl
       (const_iterator hint, const KeyType &key
       ,KeyTypeKeyCompare comp, insert_commit_data &commit_data);
 
+   //! @copydoc ::boost::intrusive::bstree::insert_unique_check(const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_unique_check
+      (const key_type &key, insert_commit_data &commit_data);
+
+   //! @copydoc ::boost::intrusive::bstree::insert_unique_check(const_iterator,const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_unique_check
+      (const_iterator hint, const key_type &key, insert_commit_data &commit_data);
+
    //! @copydoc ::boost::intrusive::bstree::insert_unique_commit
    iterator insert_unique_commit(reference value, const insert_commit_data &commit_data);
 
diff --git a/include/boost/intrusive/bs_set.hpp b/include/boost/intrusive/bs_set.hpp
index 798ffa6..60f18a1 100644
--- a/include/boost/intrusive/bs_set.hpp
+++ b/include/boost/intrusive/bs_set.hpp
@@ -197,6 +197,17 @@ class bs_set_impl
    iterator insert(const_iterator hint, reference value)
    {  return tree_type::insert_unique(hint, value);  }
 
+   //! @copydoc ::boost::intrusive::bstree::insert_unique_check(const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_check
+      (const key_type &key, insert_commit_data &commit_data)
+   {  return tree_type::insert_unique_check(key, commit_data); }
+
+   //! @copydoc ::boost::intrusive::bstree::insert_unique_check(const_iterator,const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_check
+      (const_iterator hint, const key_type &key
+      ,insert_commit_data &commit_data)
+   {  return tree_type::insert_unique_check(hint, key, commit_data); }
+
    //! @copydoc ::boost::intrusive::bstree::insert_unique_check(const KeyType&,KeyTypeKeyCompare,insert_commit_data&)
    template<class KeyType, class KeyTypeKeyCompare>
    std::pair<iterator, bool> insert_check
diff --git a/include/boost/intrusive/bstree.hpp b/include/boost/intrusive/bstree.hpp
index 147d7e6..0fb9218 100644
--- a/include/boost/intrusive/bstree.hpp
+++ b/include/boost/intrusive/bstree.hpp
@@ -476,8 +476,20 @@ struct bstbase2
    }
 
    //insert_unique_check
-   template<class KeyType, class KeyTypeKeyCompare>
    std::pair<iterator, bool> insert_unique_check
+      (const key_type &key, insert_commit_data &commit_data)
+   {  return this->insert_unique_check(key, this->key_comp(), commit_data);   }
+
+   std::pair<iterator, bool> insert_unique_check
+      (const_iterator hint, const key_type &key, insert_commit_data &commit_data)
+   {  return this->insert_unique_check(hint, key, this->key_comp(), commit_data);   }
+
+   template<class KeyType, class KeyTypeKeyCompare>
+   BOOST_INTRUSIVE_DOC1ST(std::pair<iterator BOOST_INTRUSIVE_I bool>
+      , typename detail::disable_if_convertible
+         <KeyType BOOST_INTRUSIVE_I const_iterator BOOST_INTRUSIVE_I 
+         std::pair<iterator BOOST_INTRUSIVE_I bool> >::type)
+      insert_unique_check
       (const KeyType &key, KeyTypeKeyCompare comp, insert_commit_data &commit_data)
    {
       std::pair<node_ptr, bool> ret =
@@ -488,8 +500,7 @@ struct bstbase2
 
    template<class KeyType, class KeyTypeKeyCompare>
    std::pair<iterator, bool> insert_unique_check
-      (const_iterator hint, const KeyType &key
-      ,KeyTypeKeyCompare comp, insert_commit_data &commit_data)
+      (const_iterator hint, const KeyType &key, KeyTypeKeyCompare comp, insert_commit_data &commit_data)
    {
       std::pair<node_ptr, bool> ret =
          (node_algorithms::insert_unique_check
diff --git a/include/boost/intrusive/hashtable.hpp b/include/boost/intrusive/hashtable.hpp
index 125330f..f9074c0 100644
--- a/include/boost/intrusive/hashtable.hpp
+++ b/include/boost/intrusive/hashtable.hpp
@@ -2057,8 +2057,7 @@ class hashtable_impl
    std::pair<iterator, bool> insert_unique(reference value)
    {
       insert_commit_data commit_data;
-      std::pair<iterator, bool> ret = this->insert_unique_check
-         (key_of_value()(value), this->priv_hasher(), this->priv_equal(), commit_data);
+      std::pair<iterator, bool> ret = this->insert_unique_check(key_of_value()(value), commit_data);
       if(ret.second){
          ret.first = this->insert_unique_commit(value, commit_data);
       }
@@ -2134,6 +2133,37 @@ class hashtable_impl
          , pos == this->priv_invalid_local_it());
    }
 
+   //! <b>Effects</b>: Checks if a value can be inserted in the unordered_set, using
+   //!   a user provided key instead of the value itself.
+   //!
+   //! <b>Returns</b>: If there is an equivalent value
+   //!   returns a pair containing an iterator to the already present value
+   //!   and false. If the value can be inserted returns true in the returned
+   //!   pair boolean and fills "commit_data" that is meant to be used with
+   //!   the "insert_commit" function.
+   //!
+   //! <b>Complexity</b>: Average case O(1), worst case O(this->size()).
+   //!
+   //! <b>Throws</b>: If hasher or key_compare throw. Strong guarantee.
+   //!
+   //! <b>Notes</b>: This function is used to improve performance when constructing
+   //!   a value_type is expensive: if there is an equivalent value
+   //!   the constructed object must be discarded. Many times, the part of the
+   //!   node that is used to impose the hash or the equality is much cheaper to
+   //!   construct than the value_type and this function offers the possibility to
+   //!   use that the part to check if the insertion will be successful.
+   //!
+   //!   If the check is successful, the user can construct the value_type and use
+   //!   "insert_commit" to insert the object in constant-time.
+   //!
+   //!   "commit_data" remains valid for a subsequent "insert_commit" only if no more
+   //!   objects are inserted or erased from the unordered_set.
+   //!
+   //!   After a successful rehashing insert_commit_data remains valid.
+   std::pair<iterator, bool> insert_unique_check
+      ( const key_type &key, insert_commit_data &commit_data)
+   {  return this->insert_unique_check(key, this->priv_hasher(), this->priv_equal(), commit_data);  }
+
    //! <b>Requires</b>: value must be an lvalue of type value_type. commit_data
    //!   must have been obtained from a previous call to "insert_check".
    //!   No objects should have been inserted or erased from the unordered_set between
diff --git a/include/boost/intrusive/priority_compare.hpp b/include/boost/intrusive/priority_compare.hpp
index 0cadd45..ffade48 100644
--- a/include/boost/intrusive/priority_compare.hpp
+++ b/include/boost/intrusive/priority_compare.hpp
@@ -42,10 +42,10 @@ struct priority_compare
 
 /// @cond
 
-template<class Less, class T>
+template<class PrioComp, class T>
 struct get_prio
 {
-   typedef Less type;
+   typedef PrioComp type;
 };
 
 
diff --git a/include/boost/intrusive/rbtree.hpp b/include/boost/intrusive/rbtree.hpp
index 0bcb9cf..276362d 100644
--- a/include/boost/intrusive/rbtree.hpp
+++ b/include/boost/intrusive/rbtree.hpp
@@ -263,6 +263,14 @@ class rbtree_impl
       (const_iterator hint, const KeyType &key
       ,KeyTypeKeyCompare comp, insert_commit_data &commit_data);
 
+   //! @copydoc ::boost::intrusive::bstree::insert_unique_check(const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_unique_check
+      (const key_type &key, insert_commit_data &commit_data);
+
+   //! @copydoc ::boost::intrusive::bstree::insert_unique_check(const_iterator,const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_unique_check
+      (const_iterator hint, const key_type &key, insert_commit_data &commit_data);
+
    //! @copydoc ::boost::intrusive::bstree::insert_unique_commit
    iterator insert_unique_commit(reference value, const insert_commit_data &commit_data);
 
diff --git a/include/boost/intrusive/set.hpp b/include/boost/intrusive/set.hpp
index a7d2b70..36c46c7 100644
--- a/include/boost/intrusive/set.hpp
+++ b/include/boost/intrusive/set.hpp
@@ -200,6 +200,17 @@ class set_impl
    iterator insert(const_iterator hint, reference value)
    {  return tree_type::insert_unique(hint, value);  }
 
+   //! @copydoc ::boost::intrusive::rbtree::insert_unique_check(const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_check
+      (const key_type &key, insert_commit_data &commit_data)
+   {  return tree_type::insert_unique_check(key, commit_data); }
+
+   //! @copydoc ::boost::intrusive::rbtree::insert_unique_check(const_iterator,const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_check
+      (const_iterator hint, const key_type &key
+      ,insert_commit_data &commit_data)
+   {  return tree_type::insert_unique_check(hint, key, commit_data); }
+
    //! @copydoc ::boost::intrusive::rbtree::insert_unique_check(const KeyType&,KeyTypeKeyCompare,insert_commit_data&)
    template<class KeyType, class KeyTypeKeyCompare>
    std::pair<iterator, bool> insert_check
diff --git a/include/boost/intrusive/sg_set.hpp b/include/boost/intrusive/sg_set.hpp
index c5aca1e..171bd59 100644
--- a/include/boost/intrusive/sg_set.hpp
+++ b/include/boost/intrusive/sg_set.hpp
@@ -198,6 +198,17 @@ class sg_set_impl
    iterator insert(const_iterator hint, reference value)
    {  return tree_type::insert_unique(hint, value);  }
 
+   //! @copydoc ::boost::intrusive::sgtree::insert_unique_check(const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_check
+      (const key_type &key, insert_commit_data &commit_data)
+   {  return tree_type::insert_unique_check(key, commit_data); }
+
+   //! @copydoc ::boost::intrusive::sgtree::insert_unique_check(const_iterator,const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_check
+      (const_iterator hint, const key_type &key
+      ,insert_commit_data &commit_data)
+   {  return tree_type::insert_unique_check(hint, key, commit_data); }
+
    //! @copydoc ::boost::intrusive::sgtree::insert_unique_check(const KeyType&,KeyTypeKeyCompare,insert_commit_data&)
    template<class KeyType, class KeyTypeKeyCompare>
    std::pair<iterator, bool> insert_check
@@ -323,21 +334,21 @@ class sg_set_impl
 
    #endif   //   #ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED
 
-   //! @copydoc ::boost::intrusive::rbtree::equal_range(const key_type &)
+   //! @copydoc ::boost::intrusive::sgtree::equal_range(const key_type &)
    std::pair<iterator,iterator> equal_range(const key_type &key)
    {  return this->tree_type::lower_bound_range(key); }
 
-   //! @copydoc ::boost::intrusive::rbtree::equal_range(const KeyType&,KeyTypeKeyCompare)
+   //! @copydoc ::boost::intrusive::sgtree::equal_range(const KeyType&,KeyTypeKeyCompare)
    template<class KeyType, class KeyTypeKeyCompare>
    std::pair<iterator,iterator> equal_range(const KeyType& key, KeyTypeKeyCompare comp)
    {  return this->tree_type::equal_range(key, comp); }
 
-   //! @copydoc ::boost::intrusive::rbtree::equal_range(const key_type &)const
+   //! @copydoc ::boost::intrusive::sgtree::equal_range(const key_type &)const
    std::pair<const_iterator, const_iterator>
       equal_range(const key_type &key) const
    {  return this->tree_type::lower_bound_range(key); }
 
-   //! @copydoc ::boost::intrusive::rbtree::equal_range(const KeyType&,KeyTypeKeyCompare)const
+   //! @copydoc ::boost::intrusive::sgtree::equal_range(const KeyType&,KeyTypeKeyCompare)const
    template<class KeyType, class KeyTypeKeyCompare>
    std::pair<const_iterator, const_iterator>
       equal_range(const KeyType& key, KeyTypeKeyCompare comp) const
diff --git a/include/boost/intrusive/sgtree.hpp b/include/boost/intrusive/sgtree.hpp
index 678a421..6e7af7d 100644
--- a/include/boost/intrusive/sgtree.hpp
+++ b/include/boost/intrusive/sgtree.hpp
@@ -490,7 +490,11 @@ class sgtree_impl
 
    //! @copydoc ::boost::intrusive::bstree::insert_unique_check(const KeyType&,KeyTypeKeyCompare,insert_commit_data&)
    template<class KeyType, class KeyTypeKeyCompare>
-   std::pair<iterator, bool> insert_unique_check
+   BOOST_INTRUSIVE_DOC1ST(std::pair<iterator BOOST_INTRUSIVE_I bool>
+      , typename detail::disable_if_convertible
+         <KeyType BOOST_INTRUSIVE_I const_iterator BOOST_INTRUSIVE_I 
+         std::pair<iterator BOOST_INTRUSIVE_I bool> >::type)
+      insert_unique_check
       (const KeyType &key, KeyTypeKeyCompare comp, insert_commit_data &commit_data)
    {
       std::pair<node_ptr, bool> ret =
@@ -511,6 +515,16 @@ class sgtree_impl
       return std::pair<iterator, bool>(iterator(ret.first, this->priv_value_traits_ptr()), ret.second);
    }
 
+   //! @copydoc ::boost::intrusive::bstree::insert_unique_check(const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_unique_check
+      (const key_type &key, insert_commit_data &commit_data)
+   {  return this->insert_unique_check(key, this->key_comp(), commit_data);   }
+
+   //! @copydoc ::boost::intrusive::bstree::insert_unique_check(const_iterator,const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_unique_check
+      (const_iterator hint, const key_type &key, insert_commit_data &commit_data)
+   {  return this->insert_unique_check(hint, key, this->key_comp(), commit_data);   }
+
    //! @copydoc ::boost::intrusive::bstree::insert_unique_commit
    iterator insert_unique_commit(reference value, const insert_commit_data &commit_data)
    {
diff --git a/include/boost/intrusive/splay_set.hpp b/include/boost/intrusive/splay_set.hpp
index ee2467d..893b580 100644
--- a/include/boost/intrusive/splay_set.hpp
+++ b/include/boost/intrusive/splay_set.hpp
@@ -198,6 +198,17 @@ class splay_set_impl
    iterator insert(const_iterator hint, reference value)
    {  return tree_type::insert_unique(hint, value);  }
 
+   //! @copydoc ::boost::intrusive::rbtree::insert_unique_check(const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_check
+      (const key_type &key, insert_commit_data &commit_data)
+   {  return tree_type::insert_unique_check(key, commit_data); }
+
+   //! @copydoc ::boost::intrusive::rbtree::insert_unique_check(const_iterator,const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_check
+      (const_iterator hint, const key_type &key
+      ,insert_commit_data &commit_data)
+   {  return tree_type::insert_unique_check(hint, key, commit_data); }
+
    //! @copydoc ::boost::intrusive::splaytree::insert_unique_check(const KeyType&,KeyTypeKeyCompare,insert_commit_data&)
    template<class KeyType, class KeyTypeKeyCompare>
    std::pair<iterator, bool> insert_check
diff --git a/include/boost/intrusive/splaytree.hpp b/include/boost/intrusive/splaytree.hpp
index 33ef2b1..afc1081 100644
--- a/include/boost/intrusive/splaytree.hpp
+++ b/include/boost/intrusive/splaytree.hpp
@@ -244,6 +244,14 @@ class splaytree_impl
    //! @copydoc ::boost::intrusive::bstree::insert_unique(const_iterator,reference)
    iterator insert_unique(const_iterator hint, reference value);
 
+   //! @copydoc ::boost::intrusive::bstree::insert_unique_check(const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_unique_check
+      (const key_type &key, insert_commit_data &commit_data);
+
+   //! @copydoc ::boost::intrusive::bstree::insert_unique_check(const_iterator,const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_unique_check
+      (const_iterator hint, const key_type &key, insert_commit_data &commit_data);
+
    //! @copydoc ::boost::intrusive::bstree::insert_unique_check(const KeyType&,KeyTypeKeyCompare,insert_commit_data&)
    template<class KeyType, class KeyTypeKeyCompare>
    std::pair<iterator, bool> insert_unique_check
diff --git a/include/boost/intrusive/treap.hpp b/include/boost/intrusive/treap.hpp
index f9d2e73..3852719 100644
--- a/include/boost/intrusive/treap.hpp
+++ b/include/boost/intrusive/treap.hpp
@@ -80,7 +80,7 @@ class treap_impl
          < typename get_prio
             < VoidOrPrioComp
             , typename bstree_impl
-               <ValueTraits, VoidOrKeyOfValue, VoidOrKeyComp, SizeType, ConstantTimeSize, BsTreeAlgorithms, HeaderHolder>::value_type>::type
+               <ValueTraits, VoidOrKeyOfValue, VoidOrKeyComp, SizeType, ConstantTimeSize, BsTreeAlgorithms, HeaderHolder>::key_type>::type
          >
    /// @endcond
 {
@@ -93,7 +93,7 @@ class treap_impl
    typedef tree_type                                                 implementation_defined;
    typedef get_prio
                < VoidOrPrioComp
-               , typename tree_type::value_type>                     get_prio_type;
+               , typename tree_type::key_type>                       get_prio_type;
 
    typedef detail::ebo_functor_holder
       <typename get_prio_type::type>                                 prio_base;
@@ -126,14 +126,11 @@ class treap_impl
    static const bool stateful_value_traits   = implementation_defined::stateful_value_traits;
    static const bool safemode_or_autounlink = is_safe_autounlink<value_traits::link_mode>::value;
 
-   typedef detail::key_nodeptr_comp<priority_compare, value_traits> value_node_prio_comp_t;
+   typedef detail::key_nodeptr_comp<priority_compare, value_traits, key_of_value> key_node_prio_comp_t;
 
    template<class KeyPrioComp>
-   detail::key_nodeptr_comp<KeyPrioComp, value_traits> key_node_prio_comp(KeyPrioComp keypriocomp) const
-   {  return detail::key_nodeptr_comp<KeyPrioComp, value_traits>(keypriocomp, &this->get_value_traits());  }
-
-   value_node_prio_comp_t value_node_prio_comp() const
-   {  return this->key_node_prio_comp(this->priv_pcomp()); }
+   detail::key_nodeptr_comp<KeyPrioComp, value_traits, key_of_value> key_node_prio_comp(KeyPrioComp keypriocomp) const
+   {  return detail::key_nodeptr_comp<KeyPrioComp, value_traits, key_of_value>(keypriocomp, &this->get_value_traits());  }
 
    /// @cond
    private:
@@ -414,7 +411,7 @@ class treap_impl
             ( this->tree_type::header_ptr()
             , to_insert
             , this->key_node_comp(this->key_comp())
-            , this->value_node_prio_comp())
+            , this->key_node_prio_comp(this->priv_pcomp()))
          , this->priv_value_traits_ptr());
       this->tree_type::sz_traits().increment();
       return ret;
@@ -444,7 +441,7 @@ class treap_impl
             , hint.pointed_node()
             , to_insert
             , this->key_node_comp(this->key_comp())
-            , this->value_node_prio_comp())
+            , this->key_node_prio_comp(this->priv_pcomp()))
          , this->priv_value_traits_ptr());
       this->tree_type::sz_traits().increment();
       return ret;
@@ -489,8 +486,7 @@ class treap_impl
    std::pair<iterator, bool> insert_unique(reference value)
    {
       insert_commit_data commit_data;
-      std::pair<iterator, bool> ret = this->insert_unique_check
-         (value, this->comp(), this->priv_pcomp(), commit_data);
+      std::pair<iterator, bool> ret = this->insert_unique_check(key_of_value()(value), commit_data);
       if(!ret.second)
          return ret;
       return std::pair<iterator, bool> (this->insert_unique_commit(value, commit_data), true);
@@ -514,8 +510,7 @@ class treap_impl
    iterator insert_unique(const_iterator hint, reference value)
    {
       insert_commit_data commit_data;
-      std::pair<iterator, bool> ret = this->insert_unique_check
-         (hint, value, this->comp(), this->priv_pcomp(), commit_data);
+      std::pair<iterator, bool> ret = this->insert_unique_check(hint, key_of_value()(value), commit_data);
       if(!ret.second)
          return ret.first;
       return this->insert_unique_commit(value, commit_data);
@@ -549,6 +544,68 @@ class treap_impl
       }
    }
 
+   //! <b>Effects</b>: Checks if a value can be inserted in the container, using
+   //!   a user provided key instead of the value itself.
+   //!
+   //! <b>Returns</b>: If there is an equivalent value
+   //!   returns a pair containing an iterator to the already present value
+   //!   and false. If the value can be inserted returns true in the returned
+   //!   pair boolean and fills "commit_data" that is meant to be used with
+   //!   the "insert_commit" function.
+   //!
+   //! <b>Complexity</b>: Average complexity is at most logarithmic.
+   //!
+   //! <b>Throws</b>: If the comparison or predicate functions throw. Strong guarantee.
+   //!
+   //! <b>Notes</b>: This function is used to improve performance when constructing
+   //!   a value_type is expensive: if there is an equivalent value
+   //!   the constructed object must be discarded. Many times, the part of the
+   //!   node that is used to impose the order is much cheaper to construct
+   //!   than the value_type and this function offers the possibility to use that
+   //!   part to check if the insertion will be successful.
+   //!
+   //!   If the check is successful, the user can construct the value_type and use
+   //!   "insert_commit" to insert the object in constant-time. This gives a total
+   //!   logarithmic complexity to the insertion: check(O(log(N)) + commit(O(1)).
+   //!
+   //!   "commit_data" remains valid for a subsequent "insert_commit" only if no more
+   //!   objects are inserted or erased from the container.
+   std::pair<iterator, bool> insert_unique_check
+      ( const key_type &key, insert_commit_data &commit_data)
+   {  return this->insert_unique_check(key, this->key_comp(), this->priv_pcomp(), commit_data); }
+
+   //! <b>Effects</b>: Checks if a value can be inserted in the container, using
+   //!   a user provided key instead of the value itself, using "hint"
+   //!   as a hint to where it will be inserted.
+   //!
+   //! <b>Returns</b>: If there is an equivalent value
+   //!   returns a pair containing an iterator to the already present value
+   //!   and false. If the value can be inserted returns true in the returned
+   //!   pair boolean and fills "commit_data" that is meant to be used with
+   //!   the "insert_commit" function.
+   //!
+   //! <b>Complexity</b>: Logarithmic in general, but it's amortized
+   //!   constant time if t is inserted immediately before hint.
+   //!
+   //! <b>Throws</b>: If the comparison or predicate functions throw. Strong guarantee.
+   //!
+   //! <b>Notes</b>: This function is used to improve performance when constructing
+   //!   a value_type is expensive: if there is an equivalent value
+   //!   the constructed object must be discarded. Many times, the part of the
+   //!   constructing that is used to impose the order is much cheaper to construct
+   //!   than the value_type and this function offers the possibility to use that key
+   //!   to check if the insertion will be successful.
+   //!
+   //!   If the check is successful, the user can construct the value_type and use
+   //!   "insert_commit" to insert the object in constant-time. This can give a total
+   //!   constant-time complexity to the insertion: check(O(1)) + commit(O(1)).
+   //!
+   //!   "commit_data" remains valid for a subsequent "insert_commit" only if no more
+   //!   objects are inserted or erased from the container.
+   std::pair<iterator, bool> insert_unique_check
+      ( const_iterator hint, const key_type &key, insert_commit_data &commit_data)
+   {  return this->insert_unique_check(hint, key, this->key_comp(), this->priv_pcomp(), commit_data); }
+
    //! <b>Requires</b>: comp must be a comparison function that induces
    //!   the same strict weak ordering as key_compare.
    //!   key_value_pcomp must be a comparison function that induces
@@ -583,7 +640,11 @@ class treap_impl
    //!   "commit_data" remains valid for a subsequent "insert_commit" only if no more
    //!   objects are inserted or erased from the container.
    template<class KeyType, class KeyTypeKeyCompare, class KeyValuePrioCompare>
-   std::pair<iterator, bool> insert_unique_check
+   BOOST_INTRUSIVE_DOC1ST(std::pair<iterator BOOST_INTRUSIVE_I bool>
+      , typename detail::disable_if_convertible
+         <KeyType BOOST_INTRUSIVE_I const_iterator BOOST_INTRUSIVE_I 
+         std::pair<iterator BOOST_INTRUSIVE_I bool> >::type)
+      insert_unique_check
       ( const KeyType &key, KeyTypeKeyCompare comp
       , KeyValuePrioCompare key_value_pcomp, insert_commit_data &commit_data)
    {
@@ -689,7 +750,11 @@ class treap_impl
       BOOST_INTRUSIVE_SAFE_HOOK_DEFAULT_ASSERT(!safemode_or_autounlink || node_algorithms::unique(to_insert));
       iterator ret
          ( node_algorithms::insert_before
-            ( this->tree_type::header_ptr(), pos.pointed_node(), to_insert, this->value_node_prio_comp())
+            ( this->tree_type::header_ptr()
+            , pos.pointed_node()
+            , to_insert
+            , this->key_node_prio_comp(this->priv_pcomp())
+            )
          , this->priv_value_traits_ptr());
       this->tree_type::sz_traits().increment();
       return ret;
@@ -713,7 +778,8 @@ class treap_impl
    {
       node_ptr to_insert(this->get_value_traits().to_node_ptr(value));
       BOOST_INTRUSIVE_SAFE_HOOK_DEFAULT_ASSERT(!safemode_or_autounlink || node_algorithms::unique(to_insert));
-      node_algorithms::push_back(this->tree_type::header_ptr(), to_insert, this->value_node_prio_comp());
+      node_algorithms::push_back
+         (this->tree_type::header_ptr(), to_insert, this->key_node_prio_comp(this->priv_pcomp()));
       this->tree_type::sz_traits().increment();
    }
 
@@ -735,7 +801,8 @@ class treap_impl
    {
       node_ptr to_insert(this->get_value_traits().to_node_ptr(value));
       BOOST_INTRUSIVE_SAFE_HOOK_DEFAULT_ASSERT(!safemode_or_autounlink || node_algorithms::unique(to_insert));
-      node_algorithms::push_front(this->tree_type::header_ptr(), to_insert, this->value_node_prio_comp());
+      node_algorithms::push_front
+         (this->tree_type::header_ptr(), to_insert, this->key_node_prio_comp(this->priv_pcomp()));
       this->tree_type::sz_traits().increment();
    }
 
@@ -753,7 +820,8 @@ class treap_impl
       ++ret;
       node_ptr to_erase(i.pointed_node());
       BOOST_INTRUSIVE_SAFE_HOOK_DEFAULT_ASSERT(!safemode_or_autounlink || !node_algorithms::unique(to_erase));
-      node_algorithms::erase(this->tree_type::header_ptr(), to_erase, this->value_node_prio_comp());
+      node_algorithms::erase
+         (this->tree_type::header_ptr(), to_erase, this->key_node_prio_comp(this->priv_pcomp()));
       this->tree_type::sz_traits().decrement();
       if(safemode_or_autounlink)
          node_algorithms::init(to_erase);
@@ -933,8 +1001,10 @@ class treap_impl
    template <class ExtraChecker>
    void check(ExtraChecker extra_checker) const
    {
+      typedef detail::key_nodeptr_comp<priority_compare, value_traits, key_of_value> nodeptr_prio_comp_t;
       tree_type::check(detail::treap_node_extra_checker
-         <ValueTraits, value_node_prio_comp_t, ExtraChecker>(this->value_node_prio_comp(), extra_checker));
+         <ValueTraits, nodeptr_prio_comp_t, ExtraChecker>
+            (this->key_node_prio_comp(this->priv_pcomp()), extra_checker));
    }
 
    //! @copydoc ::boost::intrusive::bstree::check()const
diff --git a/include/boost/intrusive/treap_set.hpp b/include/boost/intrusive/treap_set.hpp
index 4d26831..f97b376 100644
--- a/include/boost/intrusive/treap_set.hpp
+++ b/include/boost/intrusive/treap_set.hpp
@@ -229,6 +229,15 @@ class treap_set_impl
    iterator insert(const_iterator hint, reference value)
    {  return tree_type::insert_unique(hint, value);  }
 
+   //! @copydoc ::boost::intrusive::treap::insert_unique_check(const key_type,insert_commit_data&)
+   std::pair<iterator, bool> insert_check( const key_type &key, insert_commit_data &commit_data)
+   {  return tree_type::insert_unique_check(key, commit_data); }
+
+   //! @copydoc ::boost::intrusive::treap::insert_unique_check(const_iterator,const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_check
+      ( const_iterator hint, const key_type &key, insert_commit_data &commit_data)
+   {  return tree_type::insert_unique_check(hint, key, commit_data); }
+
    //! @copydoc ::boost::intrusive::treap::insert_unique_check(const KeyType&,KeyTypeKeyCompare,KeyValuePrioCompare,insert_commit_data&)
    template<class KeyType, class KeyTypeKeyCompare, class KeyValuePrioCompare>
    std::pair<iterator, bool> insert_check
diff --git a/include/boost/intrusive/unordered_set.hpp b/include/boost/intrusive/unordered_set.hpp
index 5148f02..1174dff 100644
--- a/include/boost/intrusive/unordered_set.hpp
+++ b/include/boost/intrusive/unordered_set.hpp
@@ -208,6 +208,10 @@ class unordered_set_impl
    void insert(Iterator b, Iterator e)
    {  table_type::insert_unique(b, e);  }
 
+   //! @copydoc ::boost::intrusive::hashtable::insert_unique_check(const key_type&,insert_commit_data&)
+   std::pair<iterator, bool> insert_check(const key_type &key, insert_commit_data &commit_data)
+   {  return table_type::insert_unique_check(key, commit_data); }
+
    //! @copydoc ::boost::intrusive::hashtable::insert_unique_check(const KeyType&,KeyHasher,KeyEqual,insert_commit_data&)
    template<class KeyType, class KeyHasher, class KeyEqual>
    std::pair<iterator, bool> insert_check
diff --git a/test/generic_set_test.hpp b/test/generic_set_test.hpp
index 074ac68..1369c27 100644
--- a/test/generic_set_test.hpp
+++ b/test/generic_set_test.hpp
@@ -191,14 +191,6 @@ struct prio_comp
    {  return this->priority_compare<int>::operator()(k.int_value(), v.int_value());  }
 };
 
-template<class ValueType>
-struct prio_comp<ValueType, ValueType>
-   : priority_compare<ValueType>
-{
-   bool operator()(const ValueType &v1, const ValueType &v2) const
-   {  return this->priority_compare<ValueType>::operator()(v1, v2);  }
-};
-
 template<class ValueTraits, class ContainerDefiner>
 void test_generic_set<ValueTraits, ContainerDefiner>::test_insert_advanced
 (value_cont_type& values, detail::true_type)
@@ -208,14 +200,16 @@ void test_generic_set<ValueTraits, ContainerDefiner>::test_insert_advanced
    typedef typename set_type::key_of_value key_of_value;
    typedef typename set_type::key_type    key_type;
    typedef typename set_type::value_type  value_type;
-   typedef prio_comp<value_type, key_type> prio_comp_t;
+   typedef priority_compare<key_type> prio_comp_t;
    {
       set_type testset;
       testset.insert(values.begin(), values.begin() + values.size());
       value_type v(1);
       typename set_type::insert_commit_data data;
-      BOOST_TEST (!testset.insert_check(key_of_value()(v), testset.key_comp(), prio_comp_t(), data).second);
-      BOOST_TEST (!testset.insert_check(testset.begin(), key_of_value()(v), testset.key_comp(), prio_comp_t(), data).second);
+      BOOST_TEST ((!testset.insert_check(key_of_value()(v), testset.key_comp(), prio_comp_t(), data).second));
+      BOOST_TEST ((!testset.insert_check(testset.begin(), key_of_value()(v), testset.key_comp(), prio_comp_t(), data).second));
+      BOOST_TEST ((!testset.insert_check(key_of_value()(v), data).second));
+      BOOST_TEST ((!testset.insert_check(testset.begin(), key_of_value()(v), data).second));
    }
 }
 
@@ -232,8 +226,10 @@ void test_generic_set<ValueTraits, ContainerDefiner>::test_insert_advanced
       testset.insert(values.begin(), values.begin() + values.size());
       value_type v(1);
       typename set_type::insert_commit_data data;
-      BOOST_TEST (!testset.insert_check(key_of_value()(v), testset.key_comp(), data).second);
-      BOOST_TEST (!testset.insert_check(testset.begin(), key_of_value()(v), testset.key_comp(), data).second);
+      BOOST_TEST ((!testset.insert_check(key_of_value()(v), testset.key_comp(), data).second));
+      BOOST_TEST ((!testset.insert_check(testset.begin(), key_of_value()(v), testset.key_comp(), data).second));
+      BOOST_TEST ((!testset.insert_check(key_of_value()(v), data).second));
+      BOOST_TEST ((!testset.insert_check(testset.begin(), key_of_value()(v), data).second));
    }
 }
 
diff --git a/test/unordered_test.hpp b/test/unordered_test.hpp
index 38d6ddc..246b716 100644
--- a/test/unordered_test.hpp
+++ b/test/unordered_test.hpp
@@ -78,14 +78,14 @@ void test_unordered<ValueTraits, ContainerDefiner>::
       test::test_maybe_unique_container(testset, values, select_t());
    }
    {
-      value_cont_type values(BucketSize);
+      value_cont_type vals(BucketSize);
       for (int i = 0; i < (int)BucketSize; ++i)
-         (&values[i])->value_ = i;
+         (&vals[i])->value_ = i;
       typename unordered_type::bucket_type buckets [BucketSize];
       unordered_type testset(bucket_traits(
          pointer_traits<typename unordered_type::bucket_ptr>::
             pointer_to(buckets[0]), BucketSize));
-      testset.insert(values.begin(), values.end());
+      testset.insert(vals.begin(), vals.end());
       test::test_iterator_forward(testset);
    }
    test_sort(values);
@@ -162,6 +162,7 @@ void test_unordered<ValueTraits, ContainerDefiner>
    typedef typename ContainerDefiner::template container
       <>::type unordered_set_type;
    typedef typename unordered_set_type::bucket_traits bucket_traits;
+   typedef typename unordered_set_type::key_of_value  key_of_value;
 
    typename unordered_set_type::bucket_type buckets [BucketSize];
    unordered_set_type testset(bucket_traits(
@@ -169,6 +170,10 @@ void test_unordered<ValueTraits, ContainerDefiner>
          pointer_to(buckets[0]), BucketSize));
    testset.insert(&values[0] + 2, &values[0] + 5);
 
+   typename unordered_set_type::insert_commit_data commit_data;
+   BOOST_TEST ((!testset.insert_check(key_of_value()(values[2]), commit_data).second));
+   BOOST_TEST (( testset.insert_check(key_of_value()(values[0]), commit_data).second));
+
    const unordered_set_type& const_testset = testset;
    if(unordered_set_type::incremental)
    {