Update to 1.71.0

Changelog:

New Libraries

    Variant2: A never-valueless, strong guarantee implementation of std::variant, from Peter Dimov.

Updated Libraries

    Align:
        Support for any integral type in the integral versions of align_up and align_down.
        Revised the implementation of aligned_allocator to no longer require a specialization for void.
        Define propagate_on_container_move_assignment and is_always_equal in aligned_allocator.
    Asio:
        Improved performance slightly by eliminating a redundant move construction when completed handlers are dispatched.
        Eliminated a compiler warning by annotating a case fall-through in the free function connect() implementation.
        Fixed the is_*_buffer_sequence detection traits for user-defined sequence types.
        Fixed some Windows-specific warnings about an incompatible pointer cast when obtaining the CancelIoEx entry point.
        Changed to automatically set the defaults when opening a serial port on Windows.
        Changed the serial port get_option() member function to be const.
        Fixed a name hiding issue with the WinRT stream-oriented socket backend's shutdown function.
        Applied a minor fix to the documentation for is_dynamic_buffer.
        Added some support for Haiku OS.
        Added wolfSSL compatability.
        Changed to require C++17 or later for coroutines TS support with clang.
        Fixed a doxygen generation problem in the tutorial.
        Ensured example programs are correctly incorporated into the documentation.
    Any:
        Static initialization of the default constructed boost::any is now possible.
        Fixed performance regression in assignment on a compilers without move-semantics.
        Maintenance work.
    Beast:
        This version consists mostly of bug fixes and performance improvements.
        Substantial work included for the split compilation mode, to reduce compile time when defining BOOST_BEAST_SEPARATE_COMPILATION.
        We'd love to know how you or your company use Beast, consider adding an item to the Companies and Individuals Using Beast list.
        See the full Release Notes for a complete list of changes.
    Circular Buffer:
        Correct doxygen generated reference to no longer show internal members. (Glen Fernandes)
        Eliminate ubsan warning on add and sub. (Glen Fernandes)
        Fix incorrect check in is_uninitialized. (Niklas Fejes)
    Container:
        Fixed bugs:
            GitHub #47: "added alignment specification for small_vector".
            GitHub #88: "Implement C++17 MoveAssignable requirements for self-move assignments".
            GitHub #107: "Alignment ignored in resource_adaptor".
            GitHub #109: "Get rid of integer overflow in copy_move_algo.hpp (-fsanitize=integer)".
            GitHub #110: "Avoid gcc 9 deprecated copy warnings in new_allocator.hpp".
            GitHub #112: "vector::resize() compilation error with msvc-10..12: data is not a member of boost::detail::aligned_storage".
            GitHub #114: "Fix small_vector noexcept specification".
            GitHub #116: "MSVC + boost 1.70 compilation error when windows.h is already included (detail/thread_mutex.hpp)".
            GitHub #117: "flat_map/map::insert_or_assign with hint has wrong return types".
            GitHub #118: "Non-unique inplace_set_difference used in in flat_tree_merge_unique and iterator invalidation in insert_unique".
            GitHub #122: "Fix has_trivial_destructor_after_move".
            GitHub #123: "With heterogeneous lookup, equal_range can result in a range with length greater than 1".
        deque can now have options, using deque_options. The block size/bytes can be be specified.
        static_vector can now have options, using static_vector_options. Alignment and throwing behaviour can be be specified.
        small_vector can now have options, using small_vector_options. Alignment and growth factor can be be specified.
    Context:
        Add support for RISC-V LP64D
        #72: Fix ABI violation on ppc64 ELFv2
        #99: cleanup of stack if creating ucontext fails
    Conversion:
        Maintenance work.
    Core:
        Added functions alloc_construct, alloc_construct_n, alloc_destroy, and alloc_destroy_n in <boost/core/alloc_construct.hpp> for allocator aware and exception safe construction and destruction of objects and arrays. (Glen Fernandes)
        Added constexpr functions first_scalar in <boost/core/first_scalar.hpp> for obtaining a pointer to the first scalar element of an array. Given a pointer of type T* they return a pointer of type remove_all_extents_t<T>*. (Glen Fernandes)
        Added class template noinit_adaptor in <boost/core/noinit_adaptor.hpp> which is an allocator adaptor that converts any allocator into one whose construct(ptr) performs default initialization via placement new, and whose destroy(ptr) invokes the value_type destructor directly. (Glen Fernandes)
        Added class template default_allocator in <boost/core/default_allocator.hpp>, which can serve as a minimal default allocator that has interface similar to C++20 std::allocator, supports configurations with disabled exceptions and does not have std as an associated namespace. The allocator uses operator new and operator delete for allocation. (Glen Fernandes)
        In <boost/core/uncaught_exceptions.hpp> header, added workarounds for better compatibility with QNX SDP 7.0 when libc++/libc++abi libraries are used. (Andrey Semashev, #59)
        The <boost/detail/sp_typeinfo.hpp> header is now marked as deprecated and will be removed in a future release. <boost/core/typeinfo.hpp> should be used instead. (Peter Dimov)
    Dynamic Bitset:
        Enabled hardware-assisted popcount on MSVC (#38).
        Added support for boost::hash and std::hash (#45).
        Support copy-initialization with default constructor (#48).
    Endian:
        Clarified requirements on the value type template parameter
        Added support for float and double
        Added endian_load, endian_store
        Updated endian_reverse to correctly support all non-bool integral types
        Moved deprecated names to the deprecated header endian.hpp
    Fiber:
        documentation for shared_work updated
    Filesystem:
        Fixed incorrect error_code returned from directory iterator increment when readdir_r is used.
        For path, fixed rvalue-aware operator/ return type to return an rvalue instead of rvalue reference. This fixes leaving a dangling reference in the user's code if the result of operator/ is bound to a const reference. (#110)
        Fixes for better compatibility with Windows CE. (#24)
        Added minimal support for CMake. (#106)
    Flyweight:
        Maintenance work.
    Histogram:
        New features:
            Support for thread-safe storages and new thread-safe accumulators
            Support for compiling without exceptions/RTTI (increases performance by 10-20 %) (with Glen Fernandes)
            Performance improvements for 1D and 2D histograms
            boost::histogram::indexed now returns forward iterator range instead of input iterator range
            boost::histogram::indexed_range::accessor is now non-copyable and acts like reference to cell value, making more algorithms from the C++ stdlib work
            boost::histogram::algorithm::reduce with new slice option and option fusion
            boost::histogram::algorithm::project accepts runtime indices for static histograms
        Bug Fixes:
            boost::histogram::algorithm::reduce also works on histograms that have some axis types without reduction support
            boost::histogram::axis::traits::update now works correctly for boost::histogram::axis::variant
        Other:
            100 % test coverage
            Reduced internal Boost dependencies
            Improved documentation and examples
            Guaranteed no-throw moves for all builtin axis types
            Compile cleanly at higher warning levels
        See changelog for more details.
    IoStreams:
        Fixed processing of multi-stream files (#87).
        Added support for multi-threaded LZMA (#95).
    Interprocess:
        GitHub #85 ("warning: Implicit conversion loses integer precision").
        GitHub #86 ("warning: Possible misuse of comma operator").
    Intrusive:
        GitHub #42: Documentation does not describe treap priority_of_value changes
        GitHub #43: Fix tests with BOOST_INTRUSIVE_VARIADIC_TEMPLATES enabled
        GitHub #45: Disable variadic templates for MSVC-12 to avoid ICEs
    LexicalCast:
        Added tests for boost::filesystem::path conversions #25.
        Maintenance work, including #28.
    Log:
        New features:
            Improved support for C++17 std::string_view in basic_formatting_ostream. The string view can now participate in character code conversion on output.
            Added auto_newline formatter and stream manipulator. It can be used to ensure that formatted output always ends with a newline while avoiding duplicate newlines.
            In the output stream, text file and text multi-file sink backends added support for configuring behavior with regard to appending a trailing newline to every formatted log record. Use auto_newline_mode named parameter of the backend constructor or call the set_auto_newline_mode method on the sink backend.
            Note: The default behavior with regard to trailing newlines added by sink backends has changed slightly compared to the previous Boost.Log releases. The backends will now only add a trailing newline if there isn't one in the formatted log message string already. In previous releases a newline was added unconditionally.
            Added support for passing arbitrary function objects in the filter and format named parameters to sink constructors and convenience functions for initializing sinks. For example, it is now possible to specify C++11 lambda functions directly in these parameters. (#63)
            In the default filter and formatter factories used in filter and formatter parsers, added support for severity level attribute values of type boost::log::trivial::severity_level. For filters, the support is limited to attributes with "Severity" name.
        Bug fixes:
            Fixed incorrect parsing of components of the rotated file names while scanning for files in the text file sink backend. If the file name pattern ended with a placeholder (for example, a file counter), the scan_for_files method would not find files matching that pattern in the target storage, leaving them unmanaged. In particular, such files would not be deleted to free target storage. (#78)
            Updated basic_formatting_ostream and basic_record_ostream to make it possible to overload stream output operators for pointers to user-defined types. User-defined operator<< overloads taking std::basic_ostream and a pointer argument should now be picked up by the compiler when the pointer is being written to one of Boost.Log streams. (#84)
        See changelog for more details.
    Math:
        New features:
            Catmull-Rom interpolator now works in C++11
            Cardinal quadratic B-spline interpolation
            Domain of elliptic integrals extended
            sin_pi and cos_pi performance improvements
            Forward-mode automatic differentiation
            Vector valued barycentric rational interpolation
            Ooura's method for evaluation of Fourier integrals
        Bug fixes:
            Multiple compatibility issues with Multiprecision fixed
            Lambert-W fixed on a rare architecture
    Metaparse:
        New features:
            In C++11 variadic template support for the following: sequence, one_of_c, one_of, repeated_one_of, repeated_one_of1, one_char_except_c, one_char_except.
        Bug fixes:
            BOOST_METAPARSE_STRING does not use out of range character values as template arguments.
            any_of_c<> does not create empty array in C++14.
    Move:
        Git Issue #26: "Invalid iterator increment/decrement in the last iteration of adaptive_sort_combine_blocks".
    Multi Array:
        Simplify allocator support by using new alloc_construct_n and alloc_destroy_n facilities from Core. (Glen Fernandes)
    Multi-index Containers:
        Added variants of const_mem_fun and mem_fun for differently qualified member functions (issue #24).
        Terse key specification syntax now correctly handles noexcept-specified member functions (issue #24).
    Outcome:
        Enhancements:
            #184 As per request from Boost release managers, relocated version.hpp and revision.hpp into detail, and added the Boost licence boilerplate to the top of every source file which was missing one (I think). Also took the opportunity to run the licence restamping script over all Outcome, so copyright dates are now up to date.
            #185 Add FAQ item explaining issue #185, and why we will do nothing to fix it right now.
            #189 Refactored the OUTCOME_TRY implementation to use more clarified customisation points capable of accepting very foreign inputs. Removed the std::experimental::expected<T, E> specialisations, as those are no longer necessary. Fixed the documentation for the customisation points which previously claimed that they are ADL discovered, which they are not. Added a recipe describing how to add in support for foreign input types.
            #183 Added a separate motivation/plug_error_code specifically for Boost.
        Bug fixes:
            OUTCOME_VERSION_MINOR hadn't been updated to 1.
            #181 Fix issue #181 where Outcome didn't actually implement the strong swap guarantee, despite being documented as doing so.
            #190 Fix issue #190 in Boost edition where unit test suite was not runnable from the Boost release distro.
            #182 Fix issue #182 where trait::is_exception_ptr_available<T> was always true, thus causing much weirdness, like not printing diagnostics and trying to feed everything to make_exception_ptr().
            #192 Fix issue #192 where the std::basic_outcome_failure_exception_from_error() was being defined twice for translation units which combine standalone and Boost Outcome's.
    Parameter:
        Upgraded keyword generation macro BOOST_PARAMETER_TEMPLATE_KEYWORD (#15).
        Moved keyword generation macro BOOST_PARAMETER_NESTED_KEYWORD from Accumulators to this library (#28).
        Added support for std::reference_wrapper and std::ref() (#16).
        Moved boost::parameter::required, boost::parameter::optional, and boost::parameter::deduced metafunction definitions to their own header files in directory boost/parameter (#18).
        Added support for Boost.Parameter-enabled function call operators (#20).
        Added support for parameter category qualifiers "forward", "consume", and "move_from" (current qualifiers are "in", "out", and "in_out") (#21) (#23) based on http://www.modernescpp.com/index.php/c-core-guidelines-how-to-pass-function-parameters. Added new usage syntax BOOST_PARAMETER_NAME((object-name), namespace-name) qualifier(tag-name)) and BOOST_PARAMETER_NAME(qualifier(name)). (Existing code that uses qualifiers directly and correctly with BOOST_PARAMETER_FUNCTION and other code generation macros should remain unaffected for now, so no breaking changes.) The reason for the change in usage is to enable applying of parameter category constraints to Boost.Parameter-enabled functions and constructors invoked through argument composition. (Otherwise, it is currently possible to use argument composition to bypass parameter category constraints applied in BOOST_PARAMETER_FUNCTION et. al.)
        Added support for perfect forwarding (#23) (#26), so that parameter::parameters::operator() can accept non-const rvalues. As a positive side effect, Boost.Parameter-enabled functions and constructors are no longer bound by BOOST_PARAMETER_MAX_ARITY on compilers that support perfect forwarding. User code can now check for this support by detecting the configuration macro BOOST_PARAMETER_HAS_PERFECT_FORWARDING, or manually turn off this support by defining the configuration macro BOOST_PARAMETER_DISABLE_PERFECT_FORWARDING.
        Added metafunctions boost::parameter::is_argument_pack (#27), boost::parameter::are_tagged_arguments (#52), and boost::parameter::result_of::compose (#75).
        Added variadic function template boost::parameter::compose() which takes in named arguments and returns them in an argument pack (#52). For compilers that do not support perfect forwarding, the configuration macro BOOST_PARAMETER_COMPOSE_MAX_ARITY determines the maximum number of arguments that boost::parameter::compose() can take in (#61).
        Added code generation macros BOOST_PARAMETER_BASIC_FUNCTION_CALL_OPERATOR, BOOST_PARAMETER_BASIC_CONST_FUNCTION_CALL_OPERATOR, BOOST_PARAMETER_NO_SPEC_FUNCTION, BOOST_PARAMETER_NO_SPEC_MEMBER_FUNCTION, BOOST_PARAMETER_NO_SPEC_CONST_MEMBER_FUNCTION, BOOST_PARAMETER_NO_SPEC_FUNCTION_CALL_OPERATOR, BOOST_PARAMETER_NO_SPEC_CONST_FUNCTION_CALL_OPERATOR, BOOST_PARAMETER_NO_SPEC_CONSTRUCTOR, and BOOST_PARAMETER_NO_SPEC_NO_BASE_CONSTRUCTOR (#52).
        Added support for Boost.MP11 (#47) (#66) (#70). User code can now check for this support by detecting the configuration macro BOOST_PARAMETER_CAN_USE_MP11, or manually turn off this support by defining the configuration macro BOOST_PARAMETER_DISABLE_MP11_USAGE.
        Improved support for parameter-dependent return types via SFINAE (#73).
    PtrContainer:
        Fix a ptr_vector regression introduced in 1.66.0 (#24).
    PolyCollection:
        Maintenance work.
    SmartPtr:
        Added aliasing constructors to weak_ptr
        Added weak_ptr<T>::empty()
        Added enable_shared_from, shared_from, and weak_from
    Stacktrace:
        Fixed output of name(), source_location() and source_line() for the default constructed frame with thread sanitizer builds in C++98 mode.
        Fixed output of long strings from name() and source_location() on MSVC #78.
        Maintenance work.
    Test:
        Boost.test v3.11 see the Changes log for more details.
        Breaking changes:
            Boost.Test shows deprecation warnings if some very old headers as deprecated. If you encounter such warnings, please follow the indications: those headers will be removed in a future release.
        New feature:
            Now BOOST_TEST can be used to compare abstract types
        Bug fixes and pull requests:
            GitHub Issues: #209, #218
            GitHub Pull Requests: #219, #224
    Utility:
        Implemented function template ostream_string in <boost/utility/ostream_string.hpp> to optimally write any kind of string content to an output stream. It satisfies the requirements of [ostream.formatted.reqmts]. (Glen Fernandes)
        Optimized the stream output operators of basic_string_view and basic_string_ref to write directly to the rdbuf stream buffer. (Glen Fernandes)
    Uuid:
        Breaking change: MD5 name-based uuid generation was corrected to be identical on all endian systems. Define BOOST_UUID_COMPAT_PRE_1_71_MD5 to keep the result in a format compatible with 1.66 through 1.70. This does not affect the default name-based uuid generation which is based on SHA1. (#109)
    Variant:
        Fixed compilation of boost::apply_visitor with variants passed by non const reference in #68. Many thanks to Ed Catmur for providing the fix.
        Added support for std::hash (#49). Macro BOOST_VARIANT_DO_NOT_SPECIALIZE_STD_HASH could be defined to avoid those specializations.
        Added micro optimizations for binary size and performance by Nikita Kniazev in #63 and #66.
        Maintenance work, including #64 by Nikita Kniazev and #67 by Hans Dembinski.
    YAP:
        Added an example showing how to make self-evaluating YAP expressions (that is, expressions that don't need an explicit call to evaluate() or transform()).


(ryoon)