Log message:
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()).

Log message:
boost: Fix DEPENDS.

Log message:
Update to 1.70.0

Changelog:
New Libraries

    Outcome: A set of tools for reporting and handling function failures in \ 
contexts where directly using C++ exception handling is unsuitable, from Niall \ 
Douglas.
    Histogram: Fast and extensible multi-dimensional histograms with convenient \ 
interface for C++14, from Hans Dembinski.

Updated Libraries

    Asio:
        This release includes a number of new features, bug fixes, performance \ 
enhancements, and documentation improvements. Notable changes include:
            Added the ability to use custom I/O executors with I/O objects (such \ 
as sockets).
            Added a new async_result form with an initiate static member function.
            Updated the Coroutines TS support and promoted it to the asio namespace.
            Added a new DynamicBuffer_v2 concept which is CopyConstructible.
            Added a new async_compose function that simplifies the \ 
implementation of user-defined asynchronous operations.
            Added a make_strand helper function.
            Relaxed the completion condition type requirements to only require \ 
move-constructibility rather than copy-constructibility.
            Added a constructor for local::basic_endpoint that takes a string_view.
            Added the noexcept qualifier to various functions.
            Added a new BOOST_ASIO_DISABLE_VISIBILITY configuration #define.
            Enabled recycling of the memory used to type-erase a function object \ 
with the polymorphic executor.
            Changed receive operations to return the correct number of bytes \ 
transferred when truncation (error::message_size) occurs on a datagram-oriented \ 
socket.
            Fixed calculation of absolute timeout when the backend uses \ 
pthread_cond_timedwait.
            Changed the range-based asynchronous connect operation to deduce the \ 
EndpointSequence iterator type.
            Fixed buffer_sequence_begin and buffer_sequence_end to prevent \ 
implicit conversion.
            Ensured SSL handshake errors are propagated to the peer before the \ 
local operation completes.
            Suppressed the eof error on SSL shutdown as it actually indicates \ 
success.
            Added a fallback error code for when we OpenSSL produces an \ 
SSL_ERROR_SYSCALL result without an associated error.
            Changed composed asynchronous read and write operations to move \ 
buffer sequence objects.
            Fixed a macOS-specific warning about the deprecation of OSMemoryBarrier.
            Fixed compile errors that occur when using the composed read and \ 
write operations with MSVC 11.0.
            Improved dispatch, post and defer documentation.
            Fixed a Windows-specific memory leak that may occur when \ 
system_executor is used.
        Consult the Revision History for further details.
    Beast: BIG Update!!!
        Some APIs have changed.
        The reference shows a star ★ next to each new item.
        Beast needs your help!
            Tell Us how you or your company use Beast
            Please report any bugs, feature requests, or general feedback
            Join the C++ Slack Workspace for free and chat with us in the #beast \ 
and #boost channels
            Don't forget to star the repository ⭐!
        More tutorials, code like the pros!
            Networking Refresher teaches you from the ground up.
            Updated Asynchronous Echo example
            Updated Detect SSL composed operation tutorial
            websocket-chat-multi threaded chat server with a JavaScript browser \ 
client
        basic_stream and tcp_stream offer:
            Timeouts: async_read_some, async_write_some complete with \ 
error::timeout on expiration!
            Traffic-shaping policies simple and unlimited, or a user-defined \ 
RatePolicy!
            Put the strand directly on the socket using P1322R0, no more \ 
bind_executor at call sites!
        Base classes async_base and stable_async_base and handle all composed \ 
operation boilerplate for you.
        ssl_stream provides a movable, assignable SSL stream with a flat write \ 
optimization.
        All asynchronous operations use Asio's async_initiate for efficient \ 
integration with Coroutines TS.
        ⚡ faster compilation, define BOOST_BEAST_SEPARATE_COMPILATION and \ 
#include <boost/beast/src.hpp> in one of your .cpp files!
        See the full Release Notes for a complete list of changes.
    Context:
        #91: cleanup of stack if creating ucontext fails
        #97: add missing BOST_CONTEXT_DECL in stack_context
        #98: fix jump_i386_sysv_macho writing garbage to the x87 control word
    Coroutine2:
        #28: don't crash on pthread_cancel
    DLL:
        New macro BOOST_DLL_USE_STD_FS. Define it to 1 to make the Boost.DLL use \ 
C++17's std::filesystem::path, std::system_error and std::error_code (#21). Note \ 
that exception types change from boost::system::system_error to \ 
std::system_error, so make sure to update catches.
        Significant rewrite of the dynamic loadable detection and decoration \ 
logic. More precise errors are now reported in case of loading failures. Added \ 
shared_library::decorate() function that returns a decorated path to the library \ 
without doing any platform related queries and detections. Prefer using \ 
shared_library::load and shared_library constructors for better results (many \ 
thanks to Loïc Touraine for the work PR#23).
        CI hardening, docs updates, typos fixes, cleanups and mg
        #196: fix high contention on remote_ready_splk_
    Filesystem:
        Fixed a few instances of dereferencing std::string::end() in path \ 
implementation.
        Fixed program termination in case of out of memory condition in \ 
directory iteratorsnce to error_code. (#58)
        Fixed possible linking errors caused by missing definitions of static \ 
members of path. (#12759)
        Fixed possible use of uninitialized data in directory iterator increment \ 
operation on Linux.
        Added support fortatus query overloads for directory_entry. This avoids \ 
a relatively expensive OS query when file status is requested for a result of \ 
dereferencing a directory iterator. (PR#55)
        Reworked current_path and read_symlink implementation to avoid \ 
possiblfilesystems. The functions now have an internal limit of the path size \ 
they will accept from the OS, which is currently 16 MiB.
        Increased the size of the internal buffer used by copy_file.
    Integer:
        Added Extended Euclidean Algorithm and Modular Multiplicative Inverse \ 
function. (Nick Thompson, PR#11)
    Log:
        New features:
            Added support for generating another log file name before collecting \ 
the file in the text file sink backend. This allows to combine appending to \ 
aexisting log file with timestamps and file counters in log filenames, and, \ 
consequently, file collection in general.
        See changelog for more details.
    Math:
        New features:
            Add Lanczos smoothing derivatives
            Move numols/ to boost/math/differentiation/finite_difference.hpp.
            Add mean, variance, skewness, kurtosis, median, Gini coefficient, \ 
and median absolute deviation to tools/univariate_statistics.hpp.
            Add correlation coefficients and covariand absolute Gini \ 
coefficient, Hoyer sparsity, oracle SNR, and the M[sub 2]M[sub 4] SNR estimator \ 
to tools/signal_statistics.hpp.
            Add total variation, l0, l1, l2, and sup norms, as well as \ 
corresponding distance functions to tools/norms.hpp.
   for polynomials, support complex coefficients, add .prime() and .integrate() \ 
methods.
            Add quadratic_roots to tools/roots.hpp.
            Add support for complex-valued functions to Newton's method in roots.hpp.
            Add Catmull-Rom inted mp_invoke to mp_invoke_q
        Added mp_similar
        Added mp_set_union, mp_set_intersection, mp_set_difference
        Added mp_not_fn
        Added mp_transform_first, mp_transform_second, mp_transform_third
        Added mp_filter
        Addedp_valid_q
        Added mp_back, mp_pop_back
    Multi-index Containers:
        size_type and difference_type are now defined as the allocator's \ 
same-named types. This will not make any difference in the vast majority of \ 
cases, but allows for some degreevia user-defined allocator types (see issue #17 \ 
for motivation). For the moment being, this change is not documented in the \ 
reference section (i.e., it has semi-official status).
        Maintenance work.
    Multiprecision:
        Fix various conversioncheck for compatibility with Boost.Optional.
        Prevent instantiation of std::numeric_limits on any old type when \ 
checking for convertibility. See #98.
        Update variable precision code to account for arbitrary precision \ 
integers. See #103.
    lization archives.
        Fix bug in fixed precision iostream formatting in mpf_float and \ 
mpfr_float. See #113.
        Add more overloads for special functions which are better handled \ 
natively by MPFR.
        Fixed bug in generic exp implementation wh.
        Fixed generic conversion from float to integer to avoid undefined \ 
behaviour. See #110.
    PolyCollection:
        Improved handling of stateful allocators and allocator propagation \ 
traits, after an error reported by Billy O'Neal (PR#9).
       ug with an internal cache structure.
    Spirit:
        Removed use of deprecated boost/detail/iterator.hpp header. PR#432
        X3
            Integer parsers should now handle user defined types. PR#429
            Note: The check_overflow trait defan \ 
std::numeric_limits<T>::is_bounded instead of \ 
boost::integer_traits<T>::is_integral.
            Removed sequence into plain parsing. Now it triggers a compile time \ 
error instead of silently parsing the the sequence and taking the last value as \ 
a resulte_rule instantiation with BOOST_SPIRIT_INSTANTIATE when:
                A rule has no attribute. PR#455
                An actual attribute is not of type a rule was declared with. \ 
PR#456 #457
            A huge thanks goes out to Xeverous for reporting    Fixed unneded \ 
attribute synthesization and no-transformation attribute reference pass-through \ 
in rules. #444 PR#449 PR#452
            Removed broken 1.0#INF parser. It was poorly documented and never \ 
worked. #415 PR#458 #8699
            The undocumenoved due to bugs PR#449 and to simplify attribute \ 
transformation. PR#460
            If you were using it to workaround bugs in attribute transformation \ 
- they should not be needed anymore as of this release.
            The integer value parser now respe10 value. PR#469
            Fixed underflow check for a (Min % Base) == 0 corner case. PR#469
            Fixed an output value on overflow of IgnoreOverflowDigits=true \ 
integer parser. PR#470
            Container attribute elements were copyied, but notial handling of \ 
references in transform_attribute was removed. PR#480
        V2
            Macro name collisions and namespace conflicts with Boost.Endian were \ 
fixed. PR#349 PR#482
            utree
                Fixed UB in tag getter due to left shi            Fixed \ 
double-conversion (spirit::string -> std::string -> spirit::string). \ 
PR#462
            Qi
                Added static asserts for rule skipper type problems. PR#427
                The check_overflow trait default implementation now \ 
reoost::integer_traits<T>::is_integral PR#429
                Integer parsers should now handle user defined types. PR#429
                Note: The check_overflow trait default implementation now relies \ 
on std::numeric_limits<T>::is_bounded instead of boosl.
                Removed broken 1.0#INF parser. It was poorly documented and \ 
never worked. #415 PR#458 #8699
                The undocumented make_attribute trait was merged into \ 
transform_attribute trait. PR#471
                The pre_transform, post_tility functions were removed in favor \ 
of directly using pre/post/fail of the transform trait. PR#467
                The integer value parser now respects \ 
std::numeric_limits<T>::digits10 value. PR#469
                Fixed underflow check for a (Min % B            Fixed an output \ 
value on overflow of IgnoreOverflowDigits=true integer parser. PR#470
                Special handling of references in transform_attribute was \ 
removed. PR#480
            Lex
                Fixed UB in default constructor of ken type. PR#420
        Classic:
            Fixed position_iterator forming reference to local when the \ 
underlying iterator dereference operator returns a non-reference type. PR#422 \ 
#9737
    Stacktrace:
        Build fix for iOS 32-bit ARM (many thanksng the fix PR#70)
        Fixed multiple typos, warnings and updated the docs.
    Test:
        Boost.test v3.10 see the Changes log for more details.
        Breaking changes:
            Boost.Test minimal.hpp is now showing a deprecation warning,
    omparison may fail tests that were silently not using the floating point \ 
comparison logic prior to this release,
            Internal API change to unit_test_log_formatter, see detailed change log,
        New feature:
            Floating point compariso non-floating point and arithmetic operands: \ 
expressions like BOOST_TEST(3.0001 == 3) now use floating point support of \ 
Boost.Test,
            Custom datasets are not required to declare the sample type field \ 
anymore,
            Extending template test riadic definition,
            Windows support for timed tests,
            Timed test on test-suites,
            Removed dependency to Boost.Timer,
            New macro BOOST_TEST_INFO_SCOPE for scoped context declaration,
            Improved BOOST_TE and pull requests:
            Trac tickets: #7397, #9434, #13106, #13418
            GitHub Issues: #133, #138, #141, #157, #160, #174, #176, #177, #180, \ 
#181, #194, #196, #198, #199, #202, #203, #204
            GitHub Pull Requests: PR#171, PR#172, PR PR#195, PR#195, PR#197, PR#205
    TypeIndex:
        Support for the GHS C++ compiler added (many thanks to Brandon \ 
Castellano for providing the patch PR#28)
        Optimized string and type comparisons (many thanks to Andrey Semashev \ 
for providing the-win compilation (many thanks to Peter Dimov for providing the \ 
patch PR#25)
        CI hardening.
    TypeTraits:
        Added is_bounded_array and is_unbounded_array (Glen Fernandes).
        Added copy_reference and copy_cv_ref (Glen Fernandes).
       /clr option.
        Misc compiler compatibility fixes.
    Variant:
        Many cleanups and internal improvements, many thanks to Nikita Kniazev \ 
(PR#55, PR#56, PR#57) and Louis Dionne (PR#51)
        CI hardening.
    uBlas:
        Addition of tensorassoy PR#65)
        Addition of basic OpenCL support (many thanks to Fady Essam PR#59)
        Integration of basic benchmark suite (many thanks to Stefan Seefeld PR#57)
        CI integration and hardening

Compilers Tested

Boost's primary test compileang: 3.0, 4.0.1, 6.0.1
        Clang, C++0x: 3.0
        Clang, C++11: 3.0, 3.1, 3.2, 3.3, 3.4, 4.0.1, 6.0.1, 7.0.0, 8.0.0
        Clang, C++14: 3.5.0, 3.6.0, 3.7.1, 3.8.0, 3.9.1, 4.0.0, 4.0.1, 5.0.2, \ 
6.0.1, 7.0.0, 8.0.0
        Clang, C++17: 5.0.2, 6.0.17, 4.5.3, 4.6.3, 5.4.0, 8.0.1
        GCC, C++0x: 4.4.7
        GCC, C++11: 4.7.3, 4.8.5, 4.9.4, 5.4.0, 6.4.0, 7.1.0, 8.0.1
        GCC, C++14: 5.4.0, 5.5.0, 6.4.0, 7.1.0, 7.3.0, 8.0.1
        GCC, C++17: 7.3.0, 8.0.1
        Intel, C++14: 18.0
    OS X:
, 9.1.0, 10.0.0
        Apple Clang, C++11: 9.0.0, 9.1.0, 10.0.0
        Apple Clang, C++14: 9.0.0, 9.1.0, 10.0.0
        Apple Clang, C++17: 9.1.0, 10.0.0
        Apple Clang, C++1z: 9.0.0
        Apple Clang, C++2a: 10.0.0
    Windows:
        GCC: 3.4.4.0, 4.5.4
        GCC, C++0x: 4.6.4
        GCC, C++11: 4.7.3, 4.8.1, 4.9.3
        GCC, C++14: 5.1.0, 5.2.0, 5.3.0, 6.1.0, 6.2.0, 6.3.0, 6.4.0
        GCC, C++17: 7.1.0, 7.2.0, 7.3.0
        Visual C++: 7.1, 8.0, 9.0, 10.0, 11.0, 12.0, 14.0, 14.1
    Fr
        Clang, C++11: 4.0.0
        Clang, C++14: 4.0.0
        Clang, C++1z: 4.0.0

Boost's additional test compilers include:

    Linux:
        Clang: 3.0, 3.8.1, 3.9.1, 4.0.1, 5.0.2, 6.0.1
        Clang, C++0x: 3.0
        Clang, C++11: 3.0, 3.1, 3..0.0, 8.0.0
        Clang, C++14: 3.5.0, 3.6.0, 3.7.1, 3.8.0, 3.9.1, 4.0.0, 4.0.1, 5.0.2, \ 
6.0.1, 7.0.0, 8.0.0
        Clang, C++17: 5.0.2, 6.0.1, 7.0.0, 8.0.0
        GCC: 4.4.7, 4.5.3, 4.6.3, 4.9.4, 5.4.0, 5.5.0, 8.0.1
        GCC, C++0x: 4.4.7
        G9.4, 5.4.0, 6.4.0, 7.1.0, 8.0.1
        GCC, C++14: 5.4.0, 5.5.0, 6.3.0, 6.4.0, 7.1.0, 7.3.0, 8.0.1, 8.1.0
        GCC, C++17: 7.3.0, 8.0.1
        Intel, C++14: 18.0
    OS X:
        Apple Clang: 9.0.0, 9.1.0, 10.0.0
        Apple Clang, C++11: 9.0.0, 9ang, C++14: 9.0.0, 9.1.0, 10.0.0
        Apple Clang, C++17: 9.1.0, 10.0.0
        Apple Clang, C++1z: 9.0.0
        Apple Clang, C++2a: 10.0.0
    Windows:
        GCC: 3.4.5, 4.1.2, 4.2.4, 4.3.3, 4.4.0, 4.5.4
        GCC, C++0x: 4.6.4
        GCC, C++11 GCC, C++14: 5.1.0, 5.2.0, 5.3.0, 6.1.0, 6.2.0, 6.3.0, 6.4.0
        GCC, C++17: 7.1.0, 7.2.0, 7.3.0
        Visual C++: 7.1, 8.0, 9.0, 10.0, 11.0, 12.0, 14.0, 14.1
    FreeBSD:
        Clang: 4.0.0
        Clang, C++11: 4.0.0
        Clang, C++14: 4.0.0

Log message:
boost: updated to 1.69.0

New Libraries

Safe Numerics:
A library for guaranteed correct integer arithmetic for C++14 and later, from \ 
Robert Ramey.

Updated Libraries

Any:
Fixed issue with visibility. Now boost::any variables constructed in one shared \ 
library with hidden visibility could be used and destroyed in other shared \ 
library with hidden visibility.
Maintenance: dropped some dependencies on other Boost libraries, fixes for docs.

Asio:
Fixed a problem with the detection of std::future availability with libstdc++.
Fixed compile error in regex overload of read_until.
Fixed a timer heap corruption issue that can occur when moving a cancelled timer.
Fixed detection of std::experimental::string_view and std::string_view with \ 
newer clang/libc++.
Fixed MSVC version detection for availability of std::invoke_result.
Fixed the buffer sequence traits to test the new requirements, if decltype is \ 
available.
Fixed an MSVC issue when building with exceptions disabled.
Added SSL context options for TLS v1.3.
Added a compile-time test for TLS v1 support.
Fixed the macro used to test for TLS v1.2 support.
Prevented global objects from being created once per thread on Windows.
Fixed a crash when using size(), max_size() or empty() on default-constructed \ 
resolver results.
Changed to move the return value in basic_resolver_results::begin() to avoid copying.
Enabled move support for the Intel Compiler.
Fixed std::string_view detection issue when using clang-cl.
Fixed the handler tracking operation name for io_context::executor_type::dispatch.
Fixed a buffer overflow that could occur when parsing an address string with a \ 
64-bit scope id.
Added examples showing how to write composed operations.
Added C++11 versions of the Timeouts, Timers, SOCKS4 and SSL examples.
Fixed minor issues in documentation and examples.

Assign:
Add rvalue reference, perfect forwarding, and variadic template support
Avoid conversion to container's allocator

Beast:
This version fixes some issues in the examples, and provides a new experimental \ 
socket which supports built-in timeouts on asynchronous operations.
New CppCon 2018 websocket chat example and presentation video.
For a complete list of changes, please view the official Release Notes.

CircularBuffer:
Use the empty base optimization for storing allocators that are empty and not \ 
final (Glen Fernandes).

Concept Check:
Removed dependency on mpl.

Context:
duplicate alias should be missing GCC alias
the clang-win toolset (clang-cl.exe) uses masm from the underlying msvc
remove useless lines in Jamfile.v2
add .file section for *_elf_gas.S files

Core:
Implemented boost::empty_value, for library authors to conveniently leverage the \ 
Empty Base Optimization to store objects of potentially empty types (Glen \ 
Fernandes). This facility is now used in Boost.Beast, Boost.CircularBuffer, \ 
Boost.MultiArray, and more.
Implemented boost::quick_exit to provide the C++11 standard library facility \ 
std::quick_exit functionality (Peter Dimov).
Reduced the number of statics in Lightweight Test, and employ lighter abort \ 
behavior for MSVC compilers upon failure to call boost::report_errors (Glen \ 
Fernandes).

DLL:
Resolved link issues with the smart library
Maintenance: fixes for docs and tests.
Dynamic Bitset:
Performance improvements (over 2x in some cases).
Added range-based set, reset, flip methods

Fiber:
unbuffered_channel push not return
Remove UTF-8 BOM at begining of the file
Fix boost-install use; should only be issued once

Filesystem:
Don't use readdir_r on Linux and Android since the readdir function is already \ 
thread-safe.
Fixed crashes in boost::filesystem::copy due to undefined behavior in the \ 
implementation.
Fixed undefined behavior in boost::filesystem::directory_iterator implementation.
Fixed compilation errors when using directory iterators with BOOST_FOREACH.
Removed workarounds for older PGI C++ compiler versions to fix compilation on \ 
the newer ones.
Fixed MSVC warnings about narrowing conversions.
Flyweight:
Fixed some issues in GCC related to Boost.MPL placeholder expression handling.
Maintenance fixes.

Function:
Removed dependencies on mpl, test

Geometry:
Karney's solution of direct geodesic problem for internal use
Discrete Frechet and Hausdorff distance algorithms
New run-time and upgraded compile-time SRS transformation interfaces \ 
(undocumented for now due to potential interface changes).

Integer:
boost/pending/integer_log2.hpp header is deprecated and will be removed in \ 
future releases. Use boost/integer/integer_log2.hpp instead.

Iostreams:
Remove call to nonexistent member seekpos() of std::fpos

Iterator:
Fixed compilation problems with ambiguous unqualified calls to advance and \ 
distance on iterators whose types involve types in the namespace boost.

LexicalCast:
Fixed sign-conversion warnings
Maintenance: dropped some dependencies on other Boost libraries, fixed build \ 
system warnings.

Log:
General changes:
Updated syslog sink backend to avoid using deprecated Boost.ASIO interfaces.
Bug fixes:
Fixed a possible incorrect estimation of the total size of rotated files in the \ 
target directory of a text file sink in some cases.
See changelog for more details.

Logic:
Breaking change: Use explicit operator bool when available

Math:
Add LambertW functions.
Update integration routines to support complex valued integrands and contour \ 
integrals.
Added the derivative of the Barycentric rational approximation.
Minor fixes to better support variable precision floating point types.
Removed use of deprecated Boost.Endian in favour of Predef.
Updated continued fraction and series evaluation code to support complex types.
Prevent logic error leading to infinite loop in toms748_solve.
Fix mean and standard_deviation for extreme_value_distribution.
Improve heuristics used in newton_raphson_iterate.
Fix result of erf(NaN).
Big push to reduce GCC warnings.
Refactor polynomial addition.
Fix for vxWorks having a real function in the global namespace.
Improve sinc approximations and add better tests.
Fix typo in Student's T hypothesis testing documentation,

Mp11:
Implemented the mp_starts_with facility (Glen Fernandes).

MultiArray:
Improve C++11 allocator model support including: Support for C++11 minimal \ 
allocators, support for stateful allocators, using the allocator for \ 
construction and destruction of the value type, and using the empty base \ 
optimization for storing empty or stateless allocators (Glen Fernandes).

Multi-index Containers:
Introduced an alternative terse key specification syntax for C++17 compliant \ 
environments.

Multiprecision:
Big update to better support variable precision types so that the precision of \ 
the result is always the largest of all the arguments.
Add support for allocators that are final in __cpp_int (Glen Fernandes).
Removed use of deprecated Boost.Endian in favour of Predef.
Add support for std::string_view.
Fixed minor bug in constant initialization.
Make assignment of non-finite value to cpp_int a runtime errors.
Added typedefs for cpp_bin_float_oct and cpp_complex_oct.

PolyCollection:
Added Bost.PolyCollection-specific versions of algorithms std::for_each_n and \ 
std::sample.

Pool:
Replace boost::mutex use to avoid a dependency on Boost.Thread

Preprocessor:
Supports the new C++ standard conforming preprocessor in VC++ 14.1, which is \ 
currently enabled by using the /experimental:preprocessor switch, in Visual \ 
Studio 2017 15.8 on up.
Rational:
Add constexpr support

Spirit.X3:
Drop own FP routines in favor of boost::math
Missing visibility mark on exception types
to_utf8: Fixed wchar_t handling on Windows

Spirit V2
Drop own FP routines in favor of boost::math
Missing visibility mark on exception types
Fixed transform_attribute ambiguity
to_utf8: Fixed wchar_t handling on Windows

Spirit.Classic:
Missing visibility mark on exception types

Stacktrace:
libbacktrace usage was significantly improved. BOOST_STACKTRACE_USE_BACKTRACE or \ 
boost_stacktrace_backtrace users are encouraged to update:
Memory consumprion dropped down.
Stack capturing became faster by an order of magnitude.
syminfo fallback enabled to provide information for visible symbols even without \ 
debug information
Exact location of the backtrace.h header now can be specified via \ 
BOOST_STACKTRACE_BACKTRACE_INCLUDE_FILE, to allow backtrace.h header usage on \ 
platforms and compilers where that header is unreachable otherwise (for example \ 
Ubuntu Xenial + Clang)
Optimized stack capturing if max_depth is set
Added to_string(const stacktrace& ) functions for fast conversion of \ 
stacktraces to std::string

System:
Boost.System is now header-only. A stub library is still built for \ 
compatibility, but linking to it is no longer necessary.
Even more functions have been marked constexpr.
The destructor of error_category is now protected and no longer virtual. This is \ 
a potentially breaking change, but its impact is expected to be limited.
error_category now has a constructor that accepts a 64 bit identifier, enabling \ 
distinct category objects to compare equal.
The constructors of error_category are now protected.
A non-allocating, nonthrowing overload of message has been added.
A virtual function failed has been added, allowing categories for which success \ 
is not synonymous with 0.
The deprecated boost::system::throws object has been removed.
boost::throws() is now deprecated and its use is discouraged.
The constructor of system_error taking a single error_code argument is now explicit.
system_error::code() now returns by value.

Test:
Boost.test v3.9 see the Changes log for more details.
New feature:
Official support of header-only variant of Boost.Test with multiple translation \ 
units.
Now possible to manually add a test case by specifying its name, with \ 
BOOST_TEST_CASE_NAME
Better support of boost::exception in the logs

TypeIndex:
Fix the regression and speed up parsing of the boost/type_traits.hpp header by 30%

Utility:
Added support for non-inheritable empty types to boost::compressed_pair by \ 
avoiding the empty base optimization for types which are declared as final (Glen \ 
Fernandes).

Variant:
Fixed issue with visibility. Now boost::bad_visit exception could cross the \ 
boundaries of shared library with hidden visibility and could be catched in \ 
other shared library with hidden visibility.

YAP:
Minor changes to support MSVC++ version 14.15 (Visual Studio 2017 version 15.8).
Doc fixes.

Log message:
py-boost: allow for pythons with the pymalloc option set

Log message:
boost: updated to 1.68.0

1.68.0:
New Libraries
YAP:
An expression template library for C++14 and later, from Zach Laine.

Updated Libraries
Beast:
This version fixes a missing executor work guard in all composed operations used \ 
in the implementation. Users who are experiencing crashes related to \ 
asynchronous completion handlers are encouraged to upgrade.
For a complete list of changes, please view the official Release Notes.
Context:
78: Linker error with context-impl=ucontext: multiple definition of \ 
boost::context::detail::current_rec
Coroutine2:
14: crash while stack unwinding
18: some guidance on why to use coroutine2
20: failes to compile test in due to the error C2039
22: undefined behaviour documentation
Fiber:
170: buffered_channel::try_push has incorrect documentation
172: WIN64: 'invalid conversion from 'HANDLE' to \ 
'std::thread::native_handle_type' errors for builds using mingw-w64
175: throw exception "Operation not permitted"
NUMA support moved to extra library (fiber-numa); enabled via property numa (numa=on)
Fusion:
Added a workaround for ambiguous call of fusion::deque constructor on GCC 4.4/c++0x
Fixed a bug with C-style array
Fixed a fusion::for_each signature to take functor by value
This may break existing code with non-copyable (non-movable) functor, but the \ 
implementation wasn't correct for a long time; the documantation was correct \ 
from the first. So, please make sure your usage.
Fixed unintentional MPL placeholder substituion bug on fusion::transform.
Moved description, how to conform Fusion sequence as MPL sequence, to mpl section.
Added notes regarding IO facility for adapted type.
Geometry:
Improvements
469 Horizontal grid shift (nadgrids) in SRS transformations (undocumented for \ 
now due to potential interface changes).
478 Box-Segment distance for spherical and geographic coordinate systems.
487 Missing combinations of geometries in distance for spherical and geographic cs
489 Additional direct geodesic problem formulas for internal use
Solved issues
470 Assertion failure with short spherical and geographic segments.
471 Invalid envelope of spherical polygon
498 Unexpected results with expand() and make_inverse() for spherical and \ 
geographic CS
Bugfixes
488 Handle non-true-references in closing_iterator and ever_circling_range_iterator
495 VxWorks 7 cross-compilation issue.
GIL:
The I/O extensions have been entirely rewritten.
The library now requires a C++11-compliant compiler.
Documentation has been reformatted and updated.
Graph:
Conditionally replace deprecated/removed C++98 std::bind1st by std::bind, \ 
std::auto_ptr by std::unique_ptr, and std::random_shuffle by std::shuffle.
Fix compiler error with release builds on VS2015
Fix the Stanford GraphBase examples
Fix friend declarations for iterator_core_access
Add missing <boost/iterator.hpp> include
Avoid an unused variable warning
Fix some typos in documentation
Fix some issues in tests and examples
Lexical Cast:
Fixes for clang-tidy warnings 12092
Log:
Improved support for VxWorks.
Save and restore ebx register on x86 PIE targets in the dump stream manipulator \ 
implementation.
Math:
Support for arbitrary precision complex valued quadrature and hence contour \ 
integration
Improve performance of polynomial addition
Math:
Continue to improve numerical integration routines, and in particular add \ 
support for contour integrals.
Improve accuracy of erfc function's rational approximations.
Multi-index Containers:
Containers of moveable but non-copyable elements can now be serialized (ticket \ 
13478). Thanks to Sébastien Paris for the report.
multi_index_container's default constructor is no longer explicit (ticket 13518).
Multiprecision:
Support for multiprecision complex numbers
Multiprecision:
Support added for complex multiprecision numbers.
Changed conversion to unsigned integer types to be truncating to match standard \ 
defined behaviour.
Correct bug in MPFR string formatting.
Fix undefined behaviour in cpp_dec_float conversion from long long.
Add support for Eigen interoperability.
float128.hpp: Fix Intel on Windows build.
Fix type used in temporaries when expanding expression templates containing \ 
mixed expressions.
Fix infinite loop in gmp_float to fixed-point string conversion.
Update the expression templates to issue static_asserts with better error \ 
messages when you try and do something unsupported.
Fix bug in cpp_int where incrementing to zero doesn't set the sign correctly.
Remove erroneous use of std::move, and rely on NVRO instead.
Fix up support for changes to MPIR-3.0.
Fix various conversion errors in cpp_bin_float when the exponent type is a long \ 
long, or else we're converting to an integer that is wider than we are.
Fix compatibility issue with GCC-8 caused by the introduction of std::byte.
Optional:
Added member function has_value() for compatibility with std::optional (issue 52).
Added member function map() for transforming optional<T> into \ 
optional<U> using a function of type T -> U.
Added member function flat_map() for transforming optional<T> into \ 
optional<U> using a function of type T -> optonal<U>.
Predef:
Add support for __ARM_ARCH macro.
Add detection for PTX architecture.
Add nvcc compiler detection.
Add support for detecting CUDA.
Remove reference to obsolete BOOST_ARCH_AMD64.
Program Options:
Support for multiple long names for an option, thanks to Eyal Rozenberg
Python:
Bug fixes to correct autolink support (Windows)
Rational:
Fixed undefined behavior in normalize()
System:
Add constexpr to error_code and error_condition members under C++14 and above
Signals:
Removal Notice: Boost.Signals will be removed in the next release. Boost.Signals \ 
was deprecated in version 1.54.0. Transition to Boost.Signals2 now to avoid \ 
disruption.
Stacktrace:
Fixed compilation on Solaris and other platforms that do qualify address as \ 
const in dladdr function (github 54).
Dropped dependency on Boost.LexicalCast.
Test:
Boost.test v3.8 see the Changes log for more details.
Breaking changes
The master_test_suite_t object is no more copyable
New feature:
Dataset test case can now use command line parameters
TypeIndex:
Dropped dependency on Boost.MPL.
Uuid:
Breaking change: sha1 detail namespace header redirection for backwards \ 
compatibility was removed
Added support for std::hash
Added support for move semantics on random generators
Properly handle EINTR when acquiring entropy
Use getrandom(2) instead of getentropy(3) on linux

Log message:
boost: updated to 1.67.0

Version 1.67.0:
New Libraries:
- Contract: Contract programming for C++.
- HOF: Higher-order functions for C++.

Updated Libraries:
- Asio:
Added missing const qualifier to basic_socket_acceptor::get_option.
Worked around a parsing error that occurs with some versions of gcc.
Fixed broken code samples in tutorial.
Added new experimental features. (Note that "experimental" features \ 
may be changed without notice in subsequent releases.)
Added experimental::detached completion token.
Added experimental::redirect_error completion token.
Added experimental::co_spawn facility for integration with the coroutines \ 
technical specification.
Updated timeout examples to use latest features.
Used asio::steady_timer rather than asio::deadline_timer.
Used asio::dynamic_buffer rather than asio::streambuf.
Used timed asio::io_context::run_for() function for blocking clients.
Added example showing a custom completion token for blocking with timeouts.
Fixed unit tests to compile when BOOST_ASIO_NO_DEPRECATED is defined.
Changed socket iostreams to use chrono by default, to fix compatibility with the \ 
Networking TS. Define BOOST_ASIO_USE_BOOST_DATE_TIME_FOR_SOCKET_IOSTREAM to \ 
enable the old Boost.Date_Time interface in basic_socket_streambuf and \ 
basic_socket_iostream.
Updated examples to use chrono rather than Boost.Date_Time.
Fixed an incorrect member function detector in the is_dynamic_buffer trait.
Fixed an async_result incompatibility with deprecated handler_type.
Added a missing move optimisation in the SSL stream implementation.
Fixed incorrect basic_resolver_results::value_type typedef.
Fixed a compile error with some OpenSSL versions when SSL_OP_NO_COMPRESSION is \ 
defined.
Changed add_certificate_authority to process multiple certificates in a bundle.
Eliminated deprecation warning with MSVC by using std::invoke_result rather than \ 
std::result_of.
Changed to use std::string_view for C++17 or later, and \ 
std::experimental::string_view for C++14. Define the preprocessor macro \ 
BOOST_ASIO_DISABLE_STD_STRING_VIEW to force the use of \ 
std::experimental::string_view (assuming it is available) when compiling in \ 
C++17 mode.
Ensured DynamicBuffer template arguments are decayed before using in enable_if tests.
Changed documentation to distinguish legacy completion handlers (which are still \ 
required to be CopyConstructible) from new MoveConstructible handlers.
Suppressed a discarded return value warning in the buffer debugging support.
Fixed basic_yield_context to work with completion signatures containing \ 
reference parameters.
Ensured that stackful coroutines launched using spawn() correctly store decayed \ 
copies of their function and handler arguments.
Fixed some compatibility issues with Android.
Added cross-compilation support to Jamfiles.
Fixed some minor portability issues in examples.

- Atomic:
Breaking change: Changed the result of the (op)_and_test operations added in \ 
Boost 1.66 to the opposite - the functions now return true if the operation \ 
result is non-zero. This is consistent with other test methods in Boost.Atomic \ 
and the C++ standard library. Users can define \ 
BOOST_ATOMIC_DETAIL_HIGHLIGHT_OP_AND_TEST when compiling their code to emit \ 
warnings on every use of the changed functions. This way users can locate the \ 
code that needs to be updated.
Update for C++2a. On C++11 compilers that support scoped enums, the memory_order \ 
enumeration is now scoped and contains constants with shorter names like \ 
acquire, release or seq_cst (i.e. users can use memory_order::acquire instead of \ 
memory_order_acquire). The old constants are also provided for backward \ 
compatibility. (P0439R0)
Update for C++2a. Added experimental support for atomic operations on floating \ 
point types. In addition to general operations, add, sub, negate operations and \ 
their fetch_(op) and opaque_(op) versions are supported. Lock-free property can \ 
be tested with the new macros BOOST_ATOMIC_FLOAT/DOUBLE/LONG_DOUBLE_LOCK_FREE. \ 
The support for floating point types is optional and can be disabled by defining \ 
BOOST_ATOMIC_NO_FLOATING_POINT. (P0020R6)
Added new experimental operations:
negate_and_test and complement_and_test which perform negation or bitwise \ 
complement and return true if the result is not zero.
add, sub, negate, bitwise_and, bitwise_or, bitwise_xor, bitwise_complement \ 
operations which perform the operation and return its result.
For generic atomic<T> specialization, the default constructor is now \ 
trivial if T's default constructor is.
The internal implementation of atomic<T> has been updated to avoid \ 
undefined behavior that stems from signed integer overflows. As required by the \ 
C++ standard, the library uses two's complement representation of signed \ 
integers internally and accroding rules of overflow. Currently, the library \ 
requires the native signed integer types to also use two's complement \ 
representation (but no defined overflow semantics).
Improved Clang support. In particular, fixed DCAS not being lock-free and fixed \ 
possible incorrect code generated on 32-bit x86.
Improved MinGW support. For gcc versions up to 4.6, fixed compilation of DCAS on x86.
In x86 PIE code, asm blocks now preserve ebx value.

- Beast:
This version fixes significant defects in websocket::stream which can lead to \ 
asserts or undefined behavior. Users are encouraged to update to the latest \ 
Boost release.
For a complete list of changes, please view the official Release Notes.

- ContainerHash:
Extracted from the functional module to break a dependency cycle.
Moved headers to new location to reflect name change, the old include paths will \ 
still work.
Added support for std::string_view, std::error_code, std::error_condition, \ 
std::optional, std::variant, std::monostate where available.
Added explicit support for vector<bool>, so that it will work with libc++.
More detail in the library change log.

- Context:
fix i386/macho routines to correctly return transfer_t in EAX/EDX
__sanitizer_finish_switch_fiber should be called directly after context switch
Clang on Windows : error: No best alternative for libs/context/build/asm_sources
fixing C2492 for execution_context (v1)
known bug: including all.hpp + <context-impl>ucontext/winfib causes error \ 
'forced_unwind: is not a member of boost::context::detail'

More info https://www.boost.org/users/history/version_1_67_0.html

Log message:
Fix indentation in buildlink3.mk files.

The actual fix as been done by "pkglint -F */*/buildlink3.mk", and was
reviewed manually.

There are some .include lines that still are indented with zero spaces
although the surrounding .if is indented. This is existing practice.

Log message:
boost: updated to 1.66.0

1.66.0:
New Libraries
Beast:
Portable HTTP, WebSocket, and network operations using only C++11 and \ 
Boost.Asio, from Vinnie Falco.

CallableTraits:
A spiritual successor to Boost.FunctionTypes, Boost.CallableTraits is a \ 
header-only C++11 library for the compile-time inspection and manipulation of \ 
all 'callable' types. Additional support for C++17 features, from Barrett Adair.

Mp11:
A C++11 metaprogramming library, from Peter Dimov.

Log message:
Bump depenency