removed limitation with legacy libstdc++-v3

doc/poly_collection.qbk

@@ -1128,6 +1128,9 @@ to allow for the definition of container-level `operator<` and related operators
 * Fixed a bug by which elements were copied rather than moved in
 allocator-extended move construction and move assigment between collections
 with non-propagating, unequal allocators.
+* Allocator-extended move construction no longer decays to allocator-extended copy
+construction for the legacy version of libstdc++-v3 shipped with GCC 4.8
+(which can also be used by Clang).
 
 [endsect]
 

include/boost/poly_collection/detail/type_info_map.hpp

@@ -1,4 +1,4 @@
-/* Copyright 2016-2018 Joaquin M Lopez Munoz.
+/* Copyright 2016-2020 Joaquin M Lopez Munoz.
  * 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)
@@ -15,6 +15,7 @@
 
 #include <boost/detail/workaround.hpp>
 #include <functional>
+#include <iterator>
 #include <memory>
 #include <type_traits>
 #include <typeinfo>
@@ -183,7 +184,6 @@ private:
   /* std::unordered_map(const allocator_type&),
    * std::unordered_map(const unordered_map&,const allocator_type&) and
    * std::unordered_map(unordered_map&&,const allocator_type&) not available.
-   * We make move construction decay to copy construction.
    */
 
   template<typename UnorderedMap>
@@ -200,10 +200,17 @@ private:
     const typename std::decay<UnorderedMap>::type::allocator_type& al)
   {
     using RawUnorderedMap=typename std::decay<UnorderedMap>::type;
+    using iterator=typename std::conditional<
+      !std::is_lvalue_reference<UnorderedMap>::value&&
+      !std::is_const<UnorderedMap>::value,
+      std::move_iterator<typename RawUnorderedMap::iterator>,
+      typename RawUnorderedMap::const_iterator
+    >::type;
 
     return RawUnorderedMap{
-      x.begin(),x.end(),0,typename RawUnorderedMap::hasher{},
-      typename RawUnorderedMap::key_equal{},al
+      iterator{x.begin()},iterator{x.end()},0,
+      typename RawUnorderedMap::hasher{},typename RawUnorderedMap::key_equal{},
+      al
     };
   }
 #else

test/test_construction.cpp

@@ -1,4 +1,4 @@
-/* Copyright 2016-2019 Joaquin M Lopez Munoz.
+/* Copyright 2016-2020 Joaquin M Lopez Munoz.
  * 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)
@@ -88,16 +88,7 @@ void test_allocator_aware_construction()
     auto                   d3=get_layout_data<Types...>(p3);
 
     BOOST_TEST(p3==p);
-
-#if BOOST_WORKAROUND(BOOST_LIBSTDCXX_VERSION,<40900)
-    /* Limitations from libstdc++-v3 force move construction with allocator
-     * to decay to copy construction with allocator.
-     */
-
-    (void)(d2==d3); /* Wunused-variable */
-#else
     if(AlwaysEqual)BOOST_TEST(d2==d3);
-#endif
 
     BOOST_TEST(p2.empty());
     do_((BOOST_TEST(!p2.template is_registered<Types>()),0)...);