Initial review version, for the review conducted from 7th December 2007 to
      16th December 2007.
    
      Unofficial release uploaded to vault, to be used with Boost 1.35.0. Incorporated
      many of the suggestions from the review.
    
- 
          Improved portability thanks to Boost regression testing.
        
- 
          Fix lots of typos, and clearer text in the documentation.
        
- 
          Fix floating point to std::size_tconversion when calculating sizes from the max load factor, and usedoublein the calculation for greater accuracy.
- 
          Fix some errors in the examples.
        
      First official release.
    
- 
          Rearrange the internals.
        
- 
          Move semantics - full support when rvalue references are available, emulated
          using a cut down version of the Adobe move library when they are not.
        
- 
          Emplace support when rvalue references and variadic template are available.
        
- 
          More efficient node allocation when rvalue references and variadic template
          are available.
        
- 
          Added equality operators.
        
- 
          Rename overload of emplacewith hint, toemplace_hintas specified in n2691.
- 
          Provide forwarding headers at <boost/unordered/unordered_map_fwd.hpp>and<boost/unordered/unordered_set_fwd.hpp>.
- 
          Move all the implementation inside boost/unordered,
          to assist modularization and hopefully make it easier to track changes
          in subversion.
- 
          Use boost::swap.
- 
          Ticket 2237:
          Document that the equality and inequality operators are undefined for two
          objects if their equality predicates aren't equivalent. Thanks to Daniel
          Krügler.
        
- 
          Ticket 1710:
          Use a larger prime number list. Thanks to Thorsten Ottosen and Hervé Brönnimann.
        
- 
          Use aligned
          storage to store the types. This changes the way the allocator
          is used to construct nodes. It used to construct the node with two calls
          to the allocator's constructmethod - once for the pointers and once for the value. It now constructs
          the node with a single call to construct and then constructs the value
          using in place construction.
- 
          Add support for C++0x initializer lists where they're available (currently
          only g++ 4.4 in C++0x mode).
        
- 
          Ticket 2756:
          Avoid a warning on Visual C++ 2009.
        
- 
          Some other minor internal changes to the implementation, tests and documentation.
        
- 
          Avoid an unnecessary copy in operator[].
- 
          Ticket 2975:
          Fix length of prime number list.
        
- 
          Ticket 2975:
          Store the prime list as a preprocessor sequence - so that it will always
          get the length right if it changes again in the future.
        
- 
          Ticket 1978:
          Implement emplacefor all
          compilers.
- 
          Ticket 2908,
          Ticket 3096:
          Some workarounds for old versions of borland, including adding explicit
          destructors to all containers.
        
- 
          Ticket 3082:
          Disable incorrect Visual C++ warnings.
        
- 
          Better configuration for C++0x features when the headers aren't available.
        
- 
          Create less buckets by default.
        
- 
          The original version made heavy use of macros to sidestep some of the older
          compilers' poor template support. But since I no longer support those compilers
          and the macro use was starting to become a maintenance burden it has been
          rewritten to use templates instead of macros for the implementation classes.
        
- 
          The container object is now smaller thanks to using boost::compressed_pairfor EBO and a slightly different function buffer - now using a bool instead
          of a member pointer.
- 
          Buckets are allocated lazily which means that constructing an empty container
          will not allocate any memory.
        
- 
          Support instantiating the containers with incomplete value types.
        
- 
          Reduced the number of warnings (mostly in tests).
        
- 
          Improved codegear compatibility.
        
- 
          Ticket 3693:
          Add erase_return_voidas
          a temporary workaround for the currenterasewhich can be inefficient because it has to find the next element to return
          an iterator.
- 
          Add templated find overload for compatible keys.
        
- 
          Ticket 3773:
          Add missing stdqualifier
          toptrdiff_t.
- 
          Some code formatting changes to fit almost all lines into 80 characters.
        
- 
          Ticket 3966:
          erase_return_voidis nowquick_erase, which is the
          current
          forerunner for resolving the slow erase by iterator, although there's
          a strong possibility that this may change in the future. The old method
          name remains for backwards compatibility but is considered deprecated and
          will be removed in a future release.
- 
          Use Boost.Exception.
        
- 
          Stop using deprecated BOOST_HAS_*macros.
- 
          Fix a bug when inserting into an unordered_maporunordered_setusing
          iterators which returnsvalue_typeby copy.
      This is major change which has been converted to use Boost.Move's move emulation,
      and be more compliant with the C++11 standard. See the compliance
      section for details.
    
      The container now meets C++11's complexity requirements, but to do so uses
      a little more memory. This means that quick_erase
      and erase_return_void are no
      longer required, they'll be removed in a future version.
    
      C++11 support has resulted in some breaking changes:
    
- 
          Equality comparison has been changed to the C++11 specification. In a container
          with equivalent keys, elements in a group with equal keys used to have
          to be in the same order to be considered equal, now they can be a permutation
          of each other. To use the old behavior define the macro BOOST_UNORDERED_DEPRECATED_EQUALITY.
- 
          The behaviour of swap is different when the two containers to be swapped
          has unequal allocators. It used to allocate new nodes using the appropriate
          allocators, it now swaps the allocators if the allocator has a member structure
          propagate_on_container_swap,
          such thatpropagate_on_container_swap::valueis true.
- 
          Allocator's constructanddestroyfunctions are called
          with raw pointers, rather than the allocator'spointertype.
- 
          emplaceused to emulate
          the variadic pair constructors that appeared in early C++0x drafts. Since
          they were removed it no longer does so. It does emulate the newpiecewise_constructpair constructors
          - only you need to useboost::piecewise_construct.
          To use the old emulation of the variadic constructors defineBOOST_UNORDERED_DEPRECATED_PAIR_CONSTRUCT.
- 
          Fix warning due to accidental odd assignment.
        
- 
          Slightly better error messages.
        
- 
          Fix equality for unordered_multisetandunordered_multimap.
- 
          Ticket 6857:
          Implement reserve.
- 
          Ticket 6771:
          Avoid gcc's -Wfloat-equalwarning.
- 
          Ticket 6784:
          Fix some Sun specific code.
        
- 
          Ticket 6190:
          Avoid gcc's -Wshadowwarning.
- 
          Ticket 6905:
          Make namespaces in macros compatible with bcpcustom namespaces. Fixed by Luke Elliott.
- 
          Remove some of the smaller prime number of buckets, as they may make collisions
          quite probable (e.g. multiples of 5 are very common because we used base
          10).
        
- 
          On old versions of Visual C++, use the container library's implementation
          of allocator_traits, as
          it's more likely to work.
- 
          On machines with 64 bit std::size_t, use power of 2 buckets, with Thomas
          Wang's hash function to pick which one to use. As modulus is very slow
          for 64 bit values.
        
- 
          Some internal changes.
        
- 
          Fix construction/destruction issue when using a C++11 compiler with a C++03
          allocator (#7100).
        
- 
          Remove a try..catchto support compiling without exceptions.
- 
          Adjust SFINAE use to try to support g++ 3.4 (#7175).
        
- 
          Updated to use the new config macros.
        
- 
          Faster assign, which assigns to existing nodes where possible, rather than
          creating entirely new nodes and copy constructing.
        
- 
          Fixed bug in erase_range(#7471).
- 
          Reverted some of the internal changes to how nodes are created, especially
          for C++11 compilers. 'construct' and 'destroy' should work a little better
          for C++11 allocators.
        
- 
          Simplified the implementation a bit. Hopefully more robust.
        
- 
          Remove support for the old pre-standard variadic pair constructors, and
          equality implementation. Both have been deprecated since Boost 1.48.
        
- 
          Remove use of deprecated config macros.
        
- 
          More internal implementation changes, including a much simpler implementation
          of erase.
- 
          Mark methods specified in standard as noexpect.
          More to come in the next release.
- 
          If the hash function and equality predicate are known to both have nothrow
          move assignment or construction then use them.
        
- 
          Avoid some warnings (#8851, #8874).
        
- 
          Avoid exposing some detail functions via. ADL on the iterators.
        
- 
          Follow the standard by only using the allocators' construct and destroy
          methods to construct and destroy stored elements. Don't use them for internal
          data like pointers.
        
- 
          Fix some shadowed variable warnings (#9377).
        
- 
          Fix allocator use in documentation (#9719).
        
- 
          Always use prime number of buckets for integers. Fixes performance regression
          when inserting consecutive integers, although makes other uses slower (#9282).
        
- 
          Only construct elements using allocators, as specified in C++11 standard.
        
- 
          Fix the pointertypedef
          in iterators (#10672).
- 
          Fix Coverity warning (GitHub
          #2).
        
- 
          Remove unnecessary template parameter from const iterators.
        
- 
          Rename private iteratortypedef in some iterator classes, as it confuses some traits classes.
- 
          Fix move assignment with stateful, propagate_on_container_move_assign allocators
          (#10777).
        
- 
          Fix rare exception safety issue in move assignment.
        
- 
          Fix potential overflow when calculating number of buckets to allocate (GitHub #4).
        
- 
          Remove use of deprecated boost::iterator.
- 
          Remove BOOST_NO_STD_DISTANCEworkaround.
- 
          Remove BOOST_UNORDERED_DEPRECATED_EQUALITYwarning.
- 
          Simpler implementation of assignment, fixes an exception safety issue for
          unordered_multisetandunordered_multimap. Might
          be a little slower.
- 
          Stop using return value SFINAE which some older compilers have issues with.
        
- 
          Check hint iterator in insert/emplace_hint.
- 
          Fix some warnings, mostly in the tests.
        
- 
          Manually write out emplace_argsfor small numbers of arguments - should make template error messages a
          little more bearable.
- 
          Remove superfluous use of boost::forwardin emplace arguments, which fixes emplacing string literals in old versions
          of Visual C++.
- 
          Fix an exception safety issue in assignment. If bucket allocation throws
          an exception, it can overwrite the hash and equality functions while leaving
          the existing elements in place. This would mean that the function objects
          wouldn't match the container elements, so elements might be in the wrong
          bucket and equivalent elements would be incorrectly handled.
        
- 
          Various reference documentation improvements.
        
- 
          Better allocator support (#12459).
        
- 
          Make the no argument constructors implicit.
        
- 
          Implement missing allocator aware constructors.
        
- 
          Fix assigning the hash/key equality functions for empty containers.
        
- 
          Remove unary/binary_function from the examples in the documentation. They
          are removed in C++17.
        
- 
          Support 10 constructor arguments in emplace. It was meant to support up
          to 10 arguments, but an off by one error in the preprocessor code meant
          it only supported up to 9.
        
- 
          Initial support for new C++17 member functions: insert_or_assignandtry_emplaceinunordered_map,
- 
          Initial support for mergeandextract. Does not include
          transferring nodes betweenunordered_mapandunordered_multimapor betweenunordered_setandunordered_multisetyet. That will hopefully be in the next version of Boost.
- 
          Add deprecated attributes to quick_eraseanderase_return_void.
          I really will remove them in a future version this time.
- 
          Small standards compliance fixes:
          
- 
                noexpectspecs forswapfree functions.
- 
                Add missing insert(P&&)methods.
 
- 
          Simpler move construction implementation.
        
- 
          Documentation fixes (GitHub
          #6).