Log message:
boost: updated to 1.85.0

Version 1.85.0

New Libraries
Charconv:
A high quality implementation of <charconv> in C++11, from Matt Borland.
Scope:
A collection of scope guard utilities and a unique_resource wrapper, from Andrey \ 
Semashev.
Updated Libraries
Asio:
Fixed the async_result primary template's concept checking to correctly handle \ 
lvalue-qualified completion signatures.
Fixed some compile errors that could arise when using the bind_allocator, \ 
bind_executor, bind_immediate_executor and bind_cancellation_slot completion \ 
token adapters to adapt each other.
Changed the experimental::ranged_parallel_group operation so that it moves the \ 
completion_order vector when invoking the completion handler.
Fixed some warnings about deprecated implicit copy constructors on \ 
ip::basic_resolver_query, io_context::strand, and coroutine.
Updated the version specification used to initialise Winsock.
Fixed co_spawn to correctly propagate exceptions resulting from cancellation to \ 
the completion handler.
Added calls to std::launder to fix undefined behaviour in awaitable<> \ 
internal storage.
Added missing handling of the file_base::append flag in the Windows \ 
implementation of file support.
Updated the socket and descriptor implementations to add more cases where they \ 
will fall back to fcntl if a call to ioctl fails.
Fixed the boost/asio/experimental/parallel_group.hpp header so that it is \ 
self-contained.
Fixed a compile error that occurred when channels and experimental::coro were \ 
both used in the same translation unit.
Added missing CancellationSlot type requirements to documentation.
Fixed the documentation hyperlinks for the deduced return types of asynchronous \ 
operations' initiating functions.
Other minor documentation updates.
Atomic:
Added support for pause instruction on RISC-V.
Beast:
API Changes
The status code list has been updated to conform with the IANA registry.
Fixes
Unreachable code warning in buffers_cat.hpp.
Connection error handling in websocker_server_awaitable example.
Concurrent calls to async_write in advanced server examples.
zlib name conflicts with minizip.
host string should be updated after SSL_set_tlsext_host_name().
Improvements
asio::associator is specialized for bind_wrapper and bind_front_wrapper.
Add non-allocating overload for error category message function.
Documentation
Specifies when calling http::message::prepare_payload() is optional.
Operations affected by basic_stream::expires_after().
teardown() and async_teardown() are customization points.
Moving or copying http::serializer after first usage is undefined behaviour.
websocket::permessage_deflate should be configured before performing the \ 
WebSocket handshake.
bytes_transferred in http reads operations reports the number of bytes consumed \ 
by the HTTP parser.
Acknowledgements
Emile Cormier, JohannesWilde, yhzx233
Bimap:
Fixed heterogeneous lookup for side collections
Bind:
C++03 is no longer supported; a C++11 compiler is required. (This includes GCC \ 
4.7 or later, and MSVC 12.0 (VS 2013) or later.)
Conversion:
Removed outdated mentions of boost::lexical_cast that is not part of the library \ 
any more. Thanks to Danil Sidoruk for the PR
Core:
Added a new boost/core/functor.hpp header with a functor class template for \ 
wrapping a raw function into a function object class.
Changed null_deleter, fclose_deleter and checked deleter definitions so that \ 
they don't bring namespace boost into argument-dependent lookup. Users may need \ 
to either explicitly qualify the namespace of the called function or add a \ 
using-declaration.
Filesystem:
path::generic_path and path::generic_string methods now remove duplicate \ 
directory separators in the returned paths.
v4: path::generic_path, path::generic_string, path::make_preferred and \ 
path::lexically_normal avoid converting between backslashes and forward slashes \ 
in path root names. For example, on Windows, \ 
path("\\\\\\\\?\\\\c:\\\\foo").generic_string() now returns \ 
"\\?\c:/foo" instead of "//?/c:/foo". Similarly, \ 
path("\\\\\\\\host/share/foo/..").lexically_normal() now returns \ 
"\\host\share".
v4: equivalent now indicates error if either one of the paths doesn't exist.
v4: absolute now returns a path with a trailing directory separator when the \ 
input path has an empty relative_path().
Added a unique_path overload taking a single error_code& ec argument. The \ 
overload generates a unique path using the default path model.
weakly_canonical now produces an absolute path if the input path is relative and \ 
contains no elements that exist in the filesystem.
Added a new copy_options::ignore_attribute_errors option for copy_file and copy \ 
operations. The new option allows to ignore possible errors while copying file \ 
attributes.
On Linux, copy_file backends based on sendfile and copy_file_range system calls \ 
will attempt to preallocate storage for the target file. This may reduce \ 
filesystem fragmentation and provide early error indication if there is not \ 
enough free space. Not all filesystems support this feature; file copying \ 
proceeds if storage preallocation is not supported.
On POSIX systems that support fdopendir, openat and related APIs defined in \ 
POSIX.1-2008, as well as on Windows, recursive_directory_iterator now uses file \ 
descriptors/handles instead of paths to query the file statuses and open nested \ 
directories during iteration. This makes directory iteration more resilient to \ 
concurrent modifications of the filesystem.
Removed APIs that were previously declared deprecated. In particular, path and \ 
recursive_directory_iterator member functions, is_regular, copy_directory, \ 
symbolic_link_exists, complete, copy_option, symlink_option, as well as \ 
boost/filesystem/convenience.hpp and boost/filesystem/path_traits.hpp headers \ 
were removed. Possible replacements for the removed components are mentioned in \ 
the documentation.
Support for path construction, assignment and appending from container types \ 
(e.g. std::vector<char>) is now disabled by default. Users can still \ 
enable this functionality by defining BOOST_FILESYSTEM_DEPRECATED. This \ 
functionality remains deprecated and will be completely removed in a future \ 
release.
Function:
C++03 is no longer supported; a C++11 compiler is required. (This includes GCC \ 
4.7 or later, and MSVC 12.0 (VS 2013) or later.)
Geometry:
Improvements
Use if constexpr macro instead of condition macro
Pass strategy to sort by side
Add cmake files for clang/mac/darwin/arm64
Solved issues
Fix invalid set operations for CCW polygons
Fix compilation error with CUDA NVCC compiler
Fix buffer of linestring returning incorrect inner polygon
Fix union operation perturbing a point and returning wrong result
Fix union producing self intersections
Fix buffer issue by setting turns in closed clusters as non traversable
Fix compilation of converter and is_base_of
Various fixes of errors and warnings
Iterator:
Support for C++03 is deprecated and will be removed in a future release.
JSON:
Boost.Endian is now used to deal with endianness.
Aliases to Boost.System and Boost.Container components are deprecated and will \ 
be completely removed in 1.87.0.
Conversion of described classes supports private members.
Rvalue reference overload for visit.
Add conversion support for path-like types.
Parsing into described classes correctly considers inherited members.
Conversion of self-referential sequences is disabled.
Fixed reference handling in visit.
LEAF:
New API for transporting of error objects and exceptions between threads: \ 
try_capture_all.
result<T> able to transport exceptions captured via try_capture_all.
result<T> transporting dynamically captured error objects with improved \ 
efficiency.
Old make_shared_context/capture APIs are deprecated, will be removed in the next \ 
release.
Removed support for transporting of dynamicaly captured error objects in exceptions.
LexicalCast:
Significant rewrite of the internal logic to separate optimized and C++ Standard \ 
Library IO-based streams:
C++ Standard Library based streams now constructed in less cases leading to \ 
better performance;
less template instantiations and simpler code;
always use std::char_traits (do not use custom traits from input/output types as \ 
it leads to linktime or runtime errors);
fixed missuse of forward declared boost::array
support for volatile input types was dropped, following the C++ Standard Library \ 
trend.
Optimized conversions from std::basic_string_view and boost::basic_string_view.
Dropped dependency on Boost.NumericConversion and Boost.MPL. Fixed some cases of \ 
converting floting point types to arithmetics.
The library now compiles and works fine with -fno-sanitize-recover=integer.
Locale:
Fix linker issues due to missing typeinfo for char8_t in C++20 mode
Fix IConv compile flags when using ICU that has a bundled IConv
collator now throws on construction, if at all, as documented
collator no longer derives from std::collator to avoid possible type confusing \ 
when it isn't available for the current backend
Throw an exception when a faulty IConv library is detected (e.g. on some MacOS \ 
versions) instead of looping indefinitely
Reduce resolution of date_time to seconds as milliseconds where not easily \ 
available causing confusion
Math:
Added a new collection of optimization algorithms:
Differential Evolution
JSO
Random Search
CMA-ES
Fix Divide by 0 warning in NCF survival function
Fix constexpr depth limits of ccmath::floor/ceil fail for large arguments
Improve accuracy of quartic_roots
Fix cstdfloat numeric limits detection macro for libstdc++14
Fix for MSVC UCRT defining _Complex_I in complex.h when using C++14
Improve cstdfloat iostream
Fix redefnition of Boost.Config macros when using standalone mode in a \ 
non-standalone environment
Significant improvements to code coverage with associated bug fixes
MSM:
Major Update. Backend update (back11). Requires C++ 11. The documentation now \ 
uses it as default.
Big new feature. New front-end (PlantUML). Requires C++ 20
Various Bugfixes (compiler errors and warnings, priority of deferred events)
Multi-index Containers:
Fixed documentation errors.
Multiprecision:
Fix deprecation warnings from C++23 <limits>
Fix cpp_bin_float for small bit counts
Fix -Wpessimizing-move
Add covecov runs
Reduce truncation in cpp_dec_float multiplication
Fix complex_adaptor to match precision requirements
Fix for breaking changes in tommath
Fix for types that can be converted to number participting in arithmetic \ 
operator overloads
MySQL:
Breaking change: Boost.MySQL now requires linking to the new Boost.Charconv \ 
compiled library. This addresses a locale-dependency problem, increases \ 
efficiency, and powers the new client-side SQL formatting feature.
Added experimental support for connection pools, which allows re-using sessions \ 
and provides built-in reconnection and error handling.
Added experimental support for type-erased connections (any_connection class). \ 
any_connection is not a template and features simpler connection establishment \ 
and reconnection semantics.
Added experimental support for client-side SQL formatting functions (format_sql \ 
and format_sql_to). These allow securely composing queries client-side, which \ 
enables patterns like batch inserts, dynamic filters or PATCH-like updates.
Fixed a performance issue affecting close_statement and async_close_statement \ 
that could cause significant delays in application code.
Added support for building with BOOST_ASIO_USE_TS_EXECUTOR_AS_DEFAULT.
The deprecated execution interface (connection::query, connection::start_query, \ 
connection::execute_statement, connection::start_statement_execution and their \ 
async counterparts) now triggers warnings, as it's scheduled for removal in \ 
Boost 1.86.
Fixed a bug that caused some error messages to be truncated.
Warning cleanup. Builds are now clean from warnings when building with -Wall and \ 
-Wextra.
All field_view constructors are now stable.
The library internals have been rewritten using a sans-io approach to reduce \ 
complexity.
Odeint:
Breaking change: The library now explicitly requires C++14 instead of implicitly \ 
by including Boost.Math
Fix compatibility with Thrust 1.10.0
Removed C++03 Boost components:
Array
Bind
Function
Static_assert
PFR:
boost::pfr::get_name now can work with local types on some compilers. Thanks to \ 
Bela Schaum for the PR
Removed unused implementation details. Thanks to Denis Mikhailov for the PR
Allow throwing exceptions from boost::pfr::structure_to_tuple. Thanks to Denis \ 
Mikhailov for the bug report.
Field reflection trick is now described in the docs.
Random:
Added splitmix64 PRNG
System:
C++03 is no longer supported; a C++11 compiler is required. (This includes GCC \ 
4.8 or later, and MSVC 14.0 (VS 2015) or later.)
The deprecated header boost/system/cygwin_error.hpp has been removed.
The original and obsolete (32 bit) MinGW is no longer supported. MinGW-w64 (both \ 
64 and 32 bit) is still supported.
operator& now works for result<void> (by way of taking a nullary function.)
Added operator|= for result.
Stacktrace:
Big new feature: stacktrace from arbitrary exception. On some POSIX platforms \ 
std::stacktrace::from_current_exception() now returns the stacktrace of the \ 
current exception object as if the stacktrace was captures at the point of \ 
throwing the exception. Many thanks to Andrei Nekrashevich for prototyping the \ 
idea in libsfe.
Fixed memory consumption on Windows with boost_stacktrace_windbg.
Fixed library build with non hidden visibility.
Added a separate section on async signal safety to the docs.
STLInterfaces:
Change the behavior of iterator_interface for input iterators in C++20 and \ 
later, to more closely follow the C++20 concepts.
Remove hidden friends from iterator_interface to fix errors about concepts being \ 
redefined with different constraints.
Add a new v3 inline namespace, containing a new iterator_interface based on \ 
deducing this instead of CRTP (C++23 and later).
Add an rvalue-qualified overload of closure::operator(), to prevent dangling \ 
temporaries.
Test:
Respect library-spcific _NO_LIB macros
Supress MSVC C4702 from __builtin_unreachable() on intentionally unreachable code
Fix boost::function streaming error
Unordered:
Optimized emplace() for a value_type or init_type (if applicable) argument to \ 
bypass creating an intermediate object. The argument is already the same type as \ 
the would-be intermediate object.
Optimized emplace() for k,v arguments on map containers to delay constructing \ 
the object until it is certain that an element should be inserted. This \ 
optimization happens when the map’s key_type is move constructible or when the \ 
k argument is a key_type.
Fixed support for allocators with explicit copy constructors
Fixed bug in the const version of unordered_multimap::find(k, hash, eq)
Variant:
Removed more of the pre-C++11 macro and workarounds.
Wave:
Fixed bugs:
Emitted pragmas lack terminating newline
YYMARKER not updated when fill called on BOOST_WAVE_BSIZE boundary
Updated Tools
Build:
Includes release of B2 version 5.1.0.

Log message:
revbump for boost-libs

Log message:
boost: updated to 1.84.0

https://www.boost.org/users/history/version_1_84_0.html

Log message:
boost: updated to 1.83.0

1.83.0

New Libraries
Compat:
A repository of C++11 implementations of standard components added in later C++ \ 
standards, from Peter Dimov and contributors.
Updated Libraries
Any:
New boost::anys::unique_any C++11 class - an alternative to boost::any (or to \ 
std::any) that does not require copy or move construction from the held type.
Ported documentation to Quickbook, Doxygen comments now used in code.
Atomic:
Fixed compilation of atomic_ref for const-qualified types. Note that even \ 
const-qualified atomic objects must still reside in read-write memory.
Chrono:
Remove use of deprecated Boost.Ratio features.
Compat:
Added latch.hpp, an implementation of std::latch (contributed by Christian Mazakas.)
Added shared_lock.hpp, a (partial) implementation of std::shared_lock \ 
(contributed by Christian Mazakas.)
Core:
Added support for incomplete types to boost::core::type_name.
Bit manipulation functions in boost/core/bit.hpp are now constexpr on recent \ 
MSVC versions (VS2019 update 5 and later.)
Added boost::core::byteswap (an implementation of std::byteswap from C++23) to \ 
boost/core/bit.hpp.
Moved the yield primitives sp_thread_pause, sp_thread_yield, sp_thread_sleep \ 
from SmartPtr implementation details to boost/core/yield_primitives.hpp.
DLL:
Fixed tests failures on glibc 2.36+, thanks to [Đoàn Trần Công \ 
Danh](https://github.com/sgn) for the bugreport.
Filesystem:
Added directory_entry::refresh method that updates internal cached file statuses \ 
for the directory entry identified by path.
v4: directory_entry constructors and modifiers that initialize or modify the \ 
path now automatically call refresh. This may result in errors that were not \ 
indicated before and in v3, if querying the filesystem for file statuses fails \ 
(e.g. if the file does not exist). This new behavior is similar to \ 
std::filesystem.
v4: directory_entry constructors and methods taking file_status parameters are \ 
removed. Users are recommended to remove these arguments and rely on \ 
directory_entry calling refresh internally.
Added directory_entry member methods for checking the file type of the file, \ 
similar to std::filesystem.
Added more methods for testing file status: is_block_file, is_character_file, \ 
is_fifo, is_socket and is_reparse_file.
recursive_directory_iterator is now more likely to reuse information about the \ 
file type that is obtained during filesystem iteration. This may improve \ 
performance.
File streams defined in boost/filesystem/fstream.hpp are now movable, if the \ 
standard library file streams are.
Added a new header boost/filesystem/cstdio.hpp with a portable fopen overload \ 
that takes path as the first argument. This function is equivalent to \ 
std::fopen, except that on Windows it uses the native wide character encoding \ 
for paths.
Generic path comparison operators are now more restricted to avoid potential \ 
ambiguities when user's code contains a using namespace boost::filesystem; \ 
directive.
Fixed potential overload resolution ambiguity in users' code, where path \ 
constructors from iterators could interfere with function overloads taking a \ 
std::initializer_list argument.
On Windows, added more workarounds for errors returned by various filesystems \ 
when creating a directory iterator.
On Windows, relaxed access rights needed for querying file times.
Flyweight:
Added smart-pointer syntax to boost::flyweight (operator* and operator-> \ 
dereferencing to the underlying value).
Fixed a situation where the mutex used by simple_locking was not recursive.
Geometry:
Improvements
Drop dependencies and replace boost with std in several places
Add missing headers so that all headers compile independently complying with \ 
Boost policy
Check const Ring concept in calculate_point_order
Solved issues
Fix for union
Fix for different geometry types
Fix for convex hull
Fix within algorithm for geometries having a pole as a vertex
Various fixes of errors and warnings
Iterator:
Added is_iterator type trait that allows to test whether the type qualifies as \ 
an iterator type.
filter_iterator now supports move-construction of the adopted iterator and the \ 
function object.
JSON:
The library now only throws system_error, except for when allocation failed, in \ 
which case std::bad_alloc is thrown.
Serialization behavior can now be changed by serialize_options.
Contextual conversions.
Parser option for more precise number parsing.
Support parse_options in stream operator<<.
Parser option to allow Infinity and NaN JSON literals.
Parser mode that only validates numbers rather than parsing them.
Numbers with exponent larger than INT_MAX are accepted by the parser and treated \ 
as infinity.
Fix object member functions that should provide strong guarantee.
Fix ambiguity of end call when boost/range.hpp is included.
Fix ASan failures.
Fix error message for error::size_mismatch.
Fix conversion into tuple with const elements.
Locale:
Bitwise/binary operators (left/right shift, binary and/or/xor/not) are no longer \ 
supported in message catalog files matching GNU gettext behavior
Std backend on Windows uses the classic locale instead of the system locale when \ 
the requested locale does not exist (now same as on other OSs)
localization_backend_manager::get is deprecated, use the generator instead
New converter classes as alternative to to_utf/from_utf/between
Fix UB on invalid index in format strings
Fix conversion of UTF to e.g. iso-2022-jp on Windows without ICU
Use long long as the count parameter for pluralized translations
Fix movability and exception specification for some classes
Log:
Fixed a possible infinite loop in text_file_backend, when the size of a \ 
formatted log record exceeds the rotation_size limit.
Math:
Added Numerical evaluation of Fourier transform of Daubechies scaling functions 921.
Added logcdf function to statistical distributions 946.
Added support for C++23's <stdfloat> types 978.
Fixed various -Wmaybe-uninitialized warnings
Fixed round and trunc functions for non-representable numbers 968.
Fixed calculation of mode for F-distribution 976.
Fixed overflow in beta distribution 977.
Fixed overflow in hypergeometric distribution 987.
Fixed calculation of median absolute deviation with non-zero center 997.
Mp11:
Added an offset/from parameter to mp_from_sequence, mp_iota, mp_iota_c.
Added mp_value, mp_list_v, mp_rename_v, mp_is_value_list.
Added value list support to the primitives in <boost/mp11/list.hpp>.
Added value list support to mp_repeat, mp_fill, mp_at, mp_back, mp_take, \ 
mp_pop_back, mp_drop, mp_insert, mp_erase.
Multi-index Containers:
Updated range insert in non-unique ordered indices to preserve insertion order \ 
of equivalent elements.
Serialization now uses std::size_t instead of unsigned long to save and load the \ 
size of a multi_index_container (unsigned long is smaller than std::size_t in \ 
LLP64 data models). multi_index_container serialization class version has been \ 
bumped from 3 to 4 to reflect this change.
Multiprecision:
Fixed bug in rational adapter division 542.
Fixed handling of global precsion changes in multi-threaded environments 552.
Fixed cpp_int::eval_convert_to noexcept specification 555.
MySQL:
Major update.
Stored procedures are now fully supported, including SELECT statements producing \ 
data and procedures with OUT parameters.
Added support for multi-queries, which allows running multiple \ 
semicolon-separated statements with a single call.
A statically-typed interface has been added, which allows parsing query results \ 
into user-provided types, using Boost.Describe structs and tuples.
Text queries and prepared statements can now be executed using the new \ 
connection::execute and connection::start_execution functions (and their async \ 
counterparts). These superseed connection::query, connection::execute_statement, \ 
connection::start_query and connection::start_statement_execution. The new \ 
functions allow access to new features, like the static interface.
A separate compilation mode has been added to help reduce build times. Sources \ 
are included in boost/mysql/src.hpp, which must be included in exactly one \ 
translation unit.
Prepared statements can now be executed using an iterator pair to specify \ 
parameters, using statement::bind and connection::execute. This enables use \ 
cases where the number and type of parameters is not known at compile-time.
Prepared statement execution now accepts parameters of type bool, std::optional \ 
and boost::optional.
Added error codes and verified compatibility with MySQL v8.0.33 and MariaDB v11.0.
Fixed potential problems with Windows' min() and max() macros.
All assertions now use Boost.Assert.
All exceptions are now thrown via Boost.ThrowException.
Immediate completions are now correctly dispatched through the I/O object executor.
Ratio:
Change default BOOST_RATIO_VERSION to 2.
Support for BOOST_RATIO_EXTENSIONS is now deprecated and will eventually be \ 
removed when Boost.Ratio is implemented in terms of the standard <ratio> \ 
header.
Test:
Added addtional older platforms to CI system (e.g. GCC 4.6)
Fixed handling of uintptr_t to make sure it is portable on 32-bit systems 353.
Fixed warnings from -Wdeprecated-copy-dtor and \ 
-Wdeprecated-copy-with-user-provided-dtor 375.
Fixed handling of check_is_close for C++23 <stdfloat> types 382.
Timer:
Remove dependency on Boost.Chrono, Boost.System, and others.
Disable deprecated headers unless BOOST_TIMER_ENABLE_DEPRECATED is defined.
Unordered:
Major update.
Added boost::concurrent_flat_map, a fast, thread-safe hashmap based on open \ 
addressing.
Sped up iteration of open-addressing containers.
In open-addressing containers, erase(iterator), which previously returned \ 
nothing, now returns a proxy object convertible to an iterator to the next \ 
element. This enables the typical it = c.erase(it) idiom without incurring any \ 
performance penalty when the returned proxy is not used.
URL:
parse_query does not recreate string_view.
url_view/string_view constructor requires non-url_view_base.
IP-literal can be IPv6addrz.
UUID:
Improved generated x86 code for AVX targets. Removed the use of lddqu \ 
instruction on SSE3 targets, which penalize performance on Intel NetBurst CPUs \ 
but is more optimal on Skylake and later CPUs.
Variant2:
Added uses_double_storage().
Updated Tools
Build:
Includes release of B2 version 4.10.1.

Log message:
boost: updated to 1.82.0

1.82.0

New Libraries
Mysql:
a C++11 client for the MySQL database server, based on Boost.Asio, from Ruben Perez.
Updated Libraries
Any:
Now uses core/enable_if.hpp header instead of the deprecated utility/enable_if.hpp.
Asio:
Added the ability to customise the execution of a completion handler when an \ 
operation completes immediately.
Added user-defined literals for buffer types.
Added a new protocol type local::seq_packet_protocol to represent AF_UNIX with \ 
SOCK_SEQPACKET.
Exposed sigaction() flags via an optional argument to signal_set::add.
Change allocator_binder, executor_binder, and cancellation_slot_binder to \ 
support detection of unspecialised associators.
Fixed ambiguity in associated_cancellation_slot<reference_wrapper>::get().
Fixed awaitable<> handling for completion signatures containing \ 
std::exception_ptr.
Fixed experimental::channel<> try_send failure after a cancel.
Fixed thread_pool::join() deadlock when the pool has no internal threads.
Fixed pipe release() when using io_uring.
Fixed data initialisation and cleanup issues in the io_uring backend.
Fixed a dangling reference issue in the execution context overload of \ 
get_associated_executor().
Ensured buffered messages can still be received when an \ 
experimental::channel<> is closed.
Fixed the any_completion_handler assignment operator.
Constrained the constructor of any_completion_handler to prevent accidental copying
Changed to use uint64_t for OpenSSL options, to match OpenSSL 3.
Fixed deferred interoperability with multiple completion signatures.
Fixed channels to add partial support for C++11 and C++14.
Added missing handler tracking source location support to co_composed and \ 
'awaitable<>' coroutines, when awaiting packaged asynchronous operations.
Fixed some 'potential null dereference' and shadow variable warnings.
Fixed a asio::buffer overload selection when used with const_buffers_1 and \ 
mutable_buffers_1.
Disabled the runtime check for current Windows version unless targeting older \ 
Windows.
Fixed compatibility between buffered stream wrappers and move-constructible \ 
streams, such as ssl::stream<>.
Fixed basic_socket_acceptor::async_accept compatibility with lambdas that have a \ 
deduced return type.
Fixed as_tuple compatibility with legacy completion tokens.
Fixed redirect_error compatibility with new completion tokens.
Fixed a potential, Windows-specific program termination due to exceptions that \ 
should have been allowed to escape from a destructor.
Prevented inadvertent co_await of boolean expressions.
Fixed result handling and support for custom allocators in experimental::use_coro.
Fixed variadic template emulation for is_async_operation and completion_signature_of.
Fixed incorrect reuse of a moved-from result in experimental::promise.
Fixed experimental::coro use with custom allocators.
Fixed seek_cur behaviour with stream-oriented files on Windows.
Various additions and modifications to the documentation.
Consult the Revision History for further details.
Atomic:
When compiled for x86 targets supporting AVX, vector instructions are now used \ 
for 128-bit atomic loads and stores.
For 32-bit x86 targets, 64-bit atomic loads and stores with memory_order_seq_cst \ 
semantics will now issue a memory ordering instruction.
Removed atomic<T>::storage() accessors and atomic<T>::storage_type \ 
types that were deprecated in Boost.Atomic 1.73. Users are recommended to use \ 
atomic<T>::value() and atomic<T>::value_type instead.
Beast:
Add error_codes use source_location
tcp_stream uses the correct executor of the timer.
error_categories use numeric ids
file_body supports seek
ContainerHash:
Added an overload of hash_value for std::nullptr_t.
Added is_tuple_like and an overload of hash_value for tuple-like types.
Changed string hashing to use mulxp1_hash. This improves both quality and speed.
Core:
Added boost/core/snprintf.hpp header with portable definitions of snprintf, \ 
vsnprintf and their wchar_t counterparts.
Deprecated boost/core/is_same.hpp and boost::core::is_same. The header will be \ 
removed in a future release. Users are advised to use Boost.TypeTraits or C++ \ 
standard library type traits instead.
Marked boost::ref member functions and associated methods with noexcept.
Marked boost::swap function with noexcept, depending on whether the type \ 
supports a non-throwing swap operation.
Added boost::core::launder, a portable implementation of std::launder.
Added BOOST_CORE_ALIGNOF, a portable implementation of alignof.
Added boost::core::max_align_t, a portable equivalent of std::max_align_t, and \ 
boost::core::max_align, the alignment of max_align_t.
Added boost::core::memory_resource, a portable equivalent of \ 
std::pmr::memory_resource from C++17.
Added boost/core/serialization.hpp, a collection of primitives allowing \ 
libraries to implement Boost.Serialization support for their types without \ 
including a Serialization header and thereby making their libraries depend on \ 
Serialization.
Added boost::data, an implementation of std::data.
Added boost::size, an implementation of std::size.
Updated boost::span to use boost::data which adds support for range construction \ 
from an std::initializer_list.
Added boost::identity, an implementation of std::identity. This facility has \ 
been moved from Boost.Functional.
DLL:
Avoid implicit cast from size_t to uint32_t
Filesystem:
Fixed compilation errors that could have been caused by path conversion \ 
constructors being too permissive on the accepted arguments.
v4: path::remove_filename now presesrves the trailing directory separator.
Added path::remove_filename_and_trailing_separators, which removes the filename \ 
and directory separators preceding it from the path. This behavior is similar to \ 
path::remove_filename in Filesystem v3, but is also usable in v4.
Added path::replace_filename, which replaces filename in a path.
Updated implementation of the library version selection to avoid ODR violations.
On Windows, added a workaround for querying file attributes for files in SMBv1 \ 
shares. Previously, directories in SMBv1 shares could have been reported as \ 
regular files. This does not affect SMBv2 or later.
Geometry:
Major improvements
Support geographic buffer for (multi)linestrings and (multi)polygons
Improvements
Comparable distance: Add support for dynamic geometries
Support covered_by() for box, geometry combinations
Solved issues
WKT: allow tabs and new lines
Fixes for union
Various fixes in examples
Breaking changes
The WKT output presentation of an empty polygon is now POLYGON() to make it \ 
consistent with other geometries
Histogram:
Replace detail::span and detail::make_span with implementations in boost::core
Documentation improvements
Protect usage of std::min and std::max in some cases, contributed by Han Jiang \ 
(min,max macros are illegially set by popular Windows headers so we need to work \ 
around)
Added test to catch usage of unprotected min,max tokens in the library in the future
Fixes to support latest clang-14 and deduction guides in gcc-11+
JSON:
set_at_pointer.
boost::hash support.
Caller-provided serializer storage.
value_to supports missing elements for std::optional.
Fix parser suspend inside an escape character.
Make sentinel() return a unique pointer.
Locale:
get_system_locale and dependents will now correctly favor LC_ALL over LC_CTYPE \ 
as defined by POSIX
utf8_codecvt::out returns partial for trailing (UTF) surrogates
Add boost::locale::util::locale_data to parse a locale
boost::locale::info::encoding() result is now in uppercase as documented, e.g. \ 
"UTF-8" instead of "utf-8"
Support M49 country codes such as en_001 or en_150
Treat en_US_POSIX as an alias for the C locale
Improve error for missing segmentation support (i.e. without ICU)
Fix compiler warnings
Math:
Deprecated C++11 support: We now require C++14 as a minimum standard. Our \ 
minimum tested compiler versions are now Clang-5, GCC-5 or MSVC-14.1.
Added Estrin's method for polynomial evaluation.
Fix various issues in non-central distributions to allow for larger \ 
non-centralities see 939.
Added CMake install target.
Fix special_functions.hpp to disable anything which can't be used in an \ 
exception-free environment.
Get condition number calculation working in C++14.
Fix constexpr table driven functions to avoid massive slowdown when the code is \ 
not actually constexpr, see 923.
Improve tanh_sinh boundary handling, see 894.
Add Linux arm64, s390x and Apple M1 testing, fix up test cases to handle 128-bit \ 
long doubles.
Improve constexpr math functions to better handle infinities and NaN's.
Make the integrators const-correct.
Fix tanh_sinh integrator in case the function underflows, see 898.
Don't use std::cbrt as some platforms still don't support it.
Stop non-central T from raising spurious FE_INVALID exceptions, see 892.
Fix binomial distribution edge case.
Improve ibeta handling of very small arguments, see 884.
Improve ibeta handling of infinities and NaN's, see 878.
Improve error handling in powm1, see 781.
Improve root-finder bracketing to bracket faster when the exponent is \ 
super-large or small.
Fix root finding edge cases, see 873.
Lots of miscellaneous warning fixes.
Add assertions when using features which require C++17 for better error messages \ 
when invoking the compiler in a lower std version.
Multi-index Containers:
Serialization now uses unsigned long instead of collection_size_type, and \ 
multi_index_container serialization class version has been bumped from 2 to 3 to \ 
reflect this change. Reading old archives may fail for custom archive types \ 
giving special treatment to collection_size_type values: if this is the case, \ 
globally define the macro \ 
BOOST_MULTI_INDEX_ENABLE_SERIALIZATION_COMPATIBILITY_V2 to ensure backwards \ 
compatibility in reading operations.
Maintenance work.
Multiprecision:
Deprecated C++11 support: We now require C++14 as a minimum standard. Our \ 
minimum tested compiler versions are now Clang-5, GCC-5 or MSVC-14.1.
Added a new forward declaration header.
Update Eigen interoperability so we no longer rely on Eigen's details, see 479.
Add Cmake install target.
Fix cpp_dec_float construction from string in standalone case for better error \ 
handling, see 499.
Remove redundent definitions when in C++17 mode, see 530.
Fix the error handling in standalone itrunc and ltrunc.
Fix potentially uninitialized storage when parsing octal strings.
Add arm64 and s390x CI testing.
Add some missing expression template unpacking code for powm, see 506.
Nowide:
Add convert_string overload accepting a (std::)string instance
Add quoted to output (quoted UTF-8) paths (std::filesystem or boost::filesystem) \ 
to streams
PFR:
Implemented the boost::pfr::is_implicitly_reflectable and the machinery for \ 
specializing aggregates as reflectable or not
Implemented boost::pfr::get by type of an element in the aggregate.
Implemented the BOOST_PFR_ENABLED macro to detect library support for reflection
Fixed missing terminating character
Fixed the boost/pfr/config.hpp compilation on older compilers
Workaround for broken C++17 stuctured binding in old compilers
Avoid -Wzero-as-null-pointer-constant warnings
Fixed multiple typos, thanks to Denis Mikhailov for the fixes.
Added missing #pragma once
Multiple fixes and improvements for the docs.
Process:
Added management for extern processes to V2 (still experimental)
Deprecated wait_for & wait_until in V1 - they will be removed in the future!
Stacktrace:
Fixed typos in docs and comments, thanks to Chocobo1 for the PR
Fixed multithreading flag detection for backtrace_create_state if \ 
BOOST_STACKTRACE_BACKTRACE_FORCE_STATIC is defined.
StaticString:
Boost.Core string_view and std::string_view interoperability
Test:
Fixed several unused variable warnings
Fixed sprintf deprecation warnings
Fixed undefined behavior in basic_cstring::rfind
Added CI through Github Actions
Unordered:
Major update.
Added node-based, open-addressing containers boost::unordered_node_map and \ 
boost::unordered_node_set.
Extended heterogeneous lookup to more member functions as specified in P2363.
Replaced the previous post-mixing process for open-addressing containers with a \ 
new algorithm based on extended multiplication by a constant.
Fixed bug in internal emplace impl where stack-local types were not properly \ 
constructed using the allocator of the container which breaks uses-allocator \ 
construction.
URL:
Add url::format with automatic percent-encoding
URL router example
set_params convenience function
Support implicit conversions to string_view
Parsing constructors are implicit
string_token::arg has virtual destructor and slice protection
Support BOOST_URL_DISABLE_THREADS
Improvements and Bug fixes:
WIN32_LEAN_AND_MEAN macro redefinition warning
Comparison differentiates absent and empty components
Detect hier_part_rule with empty-port-like segments
Segments comparison as if normalized works above root
hier-part path-rootless considers invalid segments
port as number is set to 0 when it overflows
ipv4 to string overflow detection algorithm
Variant:
Now uses core/addressof instead of the deprecated utility/addressof.

Log message:
boost: Update to 1.81.0

Changelog:
Version 1.81.0

New Libraries

  * URL: A library for parsing, modifying, and printing URLs using only C++11,
    from Vinnie Falco and Alan de Freitas. Features include fast compilation,
    strong invariants, and strict compliance using a memory-friendly approach.

Updated Libraries

  * Asio:
      + Added the consign completion token adapter, which can be used to attach
        additional values to a completion handler.
      + Added any_completion_handler<>, which can be used to type-erase
        completion handlers.
      + Added experimental::co_composed to enable lightweight implementations
        of user-defined asynchronous operations using C++20 coroutines.
      + Add range-based experimental::make_parallel_group() overloads.
      + Added any_completion_executor, a type-erased wrapper for executors that
        are associated with completion handlers.
      + Added missing context query to use_future's executor.
      + Added nothrow constructor overloads to execution::any_executor<> and
        any_io_executor.
      + Optimised representation of empty execution::any_executor objects to
        improve the performance of copy and move operations.
      + Added an associated_cancellation_slot specialisation for std::
        reference_wrapper.
      + Changed I/O objects to return their executors by const reference.
      + Changed associated to use deduced return types for all two-argument get
        functions.
      + Fixed spawn implementation to catch unhandled exceptions and rethrow
        them outside of the spawned "thread".
      + Fixed spawn to ensure the completion handler is dispatched through the
        correct executor.
      + Fixed cleanup of of terminal-state spawn "thread" objects.
      + Fixed spawn and co_spawn implementations to dispatch cancellation
        handlers on the correct executor.
      + Changed semantics of 'dispatch' to mean the executor is used as-is.
      + Deprecated the execution::execute customisation point and sender/
        receiver facilities.
      + Added a C++11 parallel_group example.
      + Fixed example code to not use the deprecated resolve conversions.
      + Fixed an ambiguity in experimental::channel_traits specialisations.
      + Added a specialised channel implementation for the for R(error_code)
        signature.
      + Made cancelled() public on the async_compose 'self' object.
      + Added io_executor_type and get_io_executor to the async_compose 'self'
        object.
      + Fixed implementation of release() for Windows overlapped handles.
      + Enabled deferred awaiting for experimental::coro, regularised
        experimental::use_coro, and fixed allocator handling.
      + Cleaned up experimental::promise and made it an asynchronous operation
        object.
      + Constrained post/defer overloads on ability to require blocking.never.
      + Changed descriptor implementation to fall back to fcntl if ioctl fails
        with ENOTTY when setting non-blocking mode.
      + Fixed Xcode deprecation warnings related to use of sprintf.
      + Fixed the arguments passed to select_reactor::run when it is run on an
        internal thread.
      + Fixed compilation errors when BOOST_ASIO_DISABLE_SMALL_BLOCK_RECYCLING
        is defined.
      + Updated detection of C++20 coroutine support on clang 14 and later.
      + Changed standard library feature detection to always enable std::
        invoke_result when targeting C++17 or later.
      + Fixed detection of return type deduction with MSVC.
      + Updated the asynchronous operation requirements to relax the
        requirements on the associated executor.
      + Added io_uring to the implementation notes.
      + Consult the Revision History for further details.
  * Beast:
      + Add buffers_generator
      + Add beast::http::message_generator
      + Added buffer_ref, so beast buffers can be used with asio.
      + Support for per-operation cancellation
      + C++20 awaitable examples.
      + websocket per-message compression options
      + websocket timeout option api
      + multiple content length error
      + Support for default-completion and rebind
  * Container Hash:
      + Major update.
      + The specializations of boost::hash have been removed; it now always
        calls hash_value.
      + Support for BOOST_HASH_NO_EXTENSIONS has been removed. The extensions
        are always enabled.
      + All standard containers are now supported. This includes std::
        forward_list and the unordered associative containers.
      + User-defined containers (types that have begin() and end() member
        functions that return iterators) are now supported out of the box.
      + Described structs and classes (those annotated with
        BOOST_DESCRIBE_STRUCT or BOOST_DESCRIBE_CLASS) are now supported out of
        the box.
      + hash_combine has been improved.
      + The performance (and quality, as a result of the above change) of
        string hashing has been improved. boost::hash for strings now passes
        SMHasher in 64 bit mode.
      + The documentation has been substantially revised to reflect the
        changes.
  * Core:
      + empty_value members are now marked as constexpr.
      + Added fclose_deleter, a deleter that calls std::fclose on a pointer to
        std::FILE.
      + Bit manipulation utilities in boost/core/bit.hpp now explicitly require
        unsigned integers on input. (#129)
      + bit_width now returns int instead of a value of the input argument
        type. This follows resolution of LWG3656.
  * Describe:
      + To allow the inclusion of enumerators.hpp, bases.hpp, and members.hpp
        when the option -pedantic is used, the invocation of
        BOOST_DESCRIBE_ENUM has been moved from modifiers.hpp into a separate
        header, modifier_description.hpp. As a consequence, modifiers.hpp no
        longer includes enum.hpp. Code that has been relying on this implicit
        inclusion may fail, and will need to be fixed to include enum.hpp.
  * DLL:
      + Fixed path_from_handle implementation for Windows platforms, thanks to
        @SaltfishAmi for the bug report 57.
  * Filesystem:
      + Deprecated: path construction, assignment and appending from containers
        of characters, such as std::vector<char> or \ 
std::list<wchar_t>, is
        deprecated in v3 and removed in v4. Please use string types or
        iterators instead.
      + Deprecated: boost/filesystem/path_traits.hpp header is deprecated and
        will be removed in a future release. The header contained
        implementation details of path and should not be used in user's code.
      + Previously deprecated APIs will now generate compilation warnings on
        use. To suppress these warnings, BOOST_FILESYSTEM_ALLOW_DEPRECATED
        macro can be defined when compiling user's code.
      + Fixed compilation due to a missing include on POSIX systems that do not
        support *at APIs. (#250)
      + On Windows prior to 10, added a workaround for network share filesystem
        that produces ERROR_INVALID_PARAMETER when constructing directory
        iterators. (PR#246, #245)
      + On Windows, fixed weakly_canonical failing with an
        ERROR_INVALID_FUNCTION error code if the path started with the \ 
"\\?\"
        prefix. (#247)
      + Added support for std::string_view, boost::string_view and boost::
        container::string (as well as respective wchar_t counterparts) in path
        constructors, assignment and appending operations. (#208)
      + path constructors, assignment and appending operations taking a pair of
        iterators will no longer accept iterators with value types that are not
        one of the supported path character types.
      + On Windows, improved compatibility of directory_iterator with various
        mounted filesystems and Wine releases prior to 7.21. (#255, #266)
      + On Windows, deduplicated files are now reported as regular files rather
        than reparse files. (#262)
  * Fusion:
      + Added fusion::identity_view (PR#240)
      + Added support for associative sequences on fusion::transform_view (PR#
        239)
      + Fixed compilation for the case when fusion::reverse_view used with an
        associative sequence (PR#237)
      + Fixed Clang 13 -Wdeprecated-copy warnings (PR#261)
      + A small dependency reorganization. Now boost::ref and boost::
        noncopyable are used from Boost.Core (PR#249)
      + Added CI testing on Linux and MacOS for clang and gcc, fixed CI testing
        on Windows (PR#245, PR#236)
      + Improved docs and fixed typos (#234, PR#235, PR#238)
  * Geometry:
      + Solved issues
          o #1048 Index: Fix dangling references when Indexable is returned by
            value by IndexableGetter
          o #1076 Union: in rare cases it might miss one polygon
          o #1081 Union: due to precision it might miss interior rings
      + Bugfixes
          o #1063 Intersection: fix a bug in intersection of simple spherical
            polygons
          o #1064 Formulas: fix a consistency issue in geodesic direct formulas
          o #1088 Point: Fix regression for custom point types
          o Various fixes for missing include files, warnings, C++20
            compilation errors and documentation
  * Histogram:
      + Major update.
      + Added new accumulators::fraction to compute fractions, their variance,
        and confidence intervals
      + Added interval computers for fractions: utility::clopper_pearson,
        utility::wilson_interval, utility::jeffreys_interval, utility::
        wald_interval which can compute intervals with arbitrary confidence
        level
      + Added utility::confidence_level and utility::deviation types to pass
        confidence levels as probabilities or in multiples of standard
        deviation for all interval computers, respectively
      + Fixed internal sub_array and span in C++20
  * Iterator:
      + function_output_iterator now supports perfect forwarding of the
        assigned values to the wrapped function object. (PR#73)
      + Fixed compilation of constructing a function_input_iterator from result
        of post-incrementing another function_input_iterator. (#75)
      + The result of post-incrementing an iterator based on iterator_facade
        now supports operator->. (it++)->foo is equivalent to (*it++).foo,
        which was supported before.
  * JSON:
      + Added object::stable_erase.
      + Added parse overload for std::istream and operator>> for value.
      + Added rvalue ref-qualified accessors for value.
      + Conversion traits were redesigned.
      + Added conversion support for described classes and enums, std::optional
        , std::variant, and null-like types (including std::nullptr_t, std::
        nullopt_t, and std::monotype).
      + Added non-throwing conversion from value to user types.
  * LexicalCast:
      + Fixed compilation while casting volatile arithmetic types. Thanks to
        Giovanni Cerretani for the bug report #50.
      + Removed usage of deprecated headers. Thanks to Michael Ford for the PR
        PR#53.
  * Locale:
      + Major update with some breaking changes.
      + C++11 support is now required, support for C++03 and earlier is dropped
      + Some enums have been converted to enum classes - Avoids name clashes
      + Replace -sICU_LINK_LOCALE & -sICU_LINK by fine-grained configuration
        options as done in Boost.RegEx
      + Fix detection of libiconv allowing Boost.Locale to be build (again) on
        some platforms
      + Remove use of and support for std::auto_ptr
      + Make the codecvt using wchar_t on Windows assume/use UTF-16 enconding
      + Performance improvements: Make basic_format, date_time & hold_ptr
        movable, Fix use of format cache
      + Make Boost.Locale compatible with more ICU versions (especially the
        tests)
      + Fix RTTI definitions for some classes (visibility issues)
      + Fix compatibility of the ICU backend with some libc++ versions
      + Fix return value of some operators to correctly return non-const *this
      + Fix int-overflow on negative roll of years in date_time
      + Handle or suppress many warnings which makes the build log cleaner
      + Add support for more Windows codepages
      + Fix support for Windows codepages like ISO-2022-JP
  * Nowide:
      + Fix build failure of tests on MSVC
  * Stacktrace:
      + The library does not use COM initialization any more. Thanks to Alex
        Guteniev for the bug report, clarifications and PR PR#123!
      + The library now may use BOOST_STACKTRACE_BACKTRACE_INCLUDE_FILE macro
        value while detecting the libbacktrace availability in b2, thanks to
        Ben Gemmill for the bug report #115.
      + Added BOOST_STACKTRACE_BACKTRACE_FORCE_STATIC macro to force a single
        backtrace_state static instance while using the libbacktrace. Thanks to
        the Rasmus Thomsen for the bug report #118!
      + Avoid unresolved references when including only the boost/stacktrace/
        stacktrace.hpp header. Thanks to the Long Deng for the bug report #116.
      + Optimized stacktrace printing by not calling strlen on Windows
        platforms. Thanks to Alex Guteniev for the bug report #122
  * PFR:
      + Improved detection of aggregate initializables in C++14 mode, thanks to
        Denis Mikhailov for the PR PR#97.
      + Suppress clang-tidy warnings, thanks to Alexander Malkov for the PRs PR
        #109, PR#104.
      + Use fold expressions if they are supported by the compiler. Thanks to
        Jean-Micha?l Celerier for the PR PR#96.
  * STLInterfaces:
      + Fix two ill-formed iterator_interface operators in pre-C++20 iterators
        with a const value_type.
  * System:
      + The macro BOOST_SYSTEM_DISABLE_THREADS can now be defined to disable
        the use of <mutex> (e.g. on single-threaded libstdc++).
      + Added value_type, error_type, in_place_value, in_place_error to result
        <>.
      + Added emplace to result<>.
  * Unordered:
      + Major update.
      + Added fast containers boost::unordered_flat_map and boost::
        unordered_flat_set based on open addressing.
      + Added CTAD deduction guides for all containers.
      + Added missing constructors as specified in LWG issue 2713.
  * Variant:
      + Avoid recursive inclusion of headers, thanks to Nathan Sidwell for the
        bug report #101.
      + Removed usage of deprecated headers, thanks to Michael Ford for the PR
        PR#96.
      + Fixed compilation on clang in C++23 mode, thanks to Ed Catmur for the
        PR PR#98.
  * Variant2:
      + Added support for boost::json::value_from and boost::json::value_to.

Version 1.80.0

Known Issues

These are patches from library authors which were found too late to be fixed in
the release.

  * Config
      + Support for libcpp15 which removes std::unary_function and std::
        binary_function. Patch.
  * Filesystem
      + Directory iterators may fail to construct for a network share on
        Windows prior to 10, see PR#246 and #245. Patch.
      + On Windows, weakly_canonical fails to process paths that start with the
        "\\?\" prefix, see #247. Patch.
      + On POSIX systems that don't support *at APIs, compilation fails due to
        a missing include, see #250. Patch.
  * Unordered
      + Containers are not in a valid state after moving, see #139. Patch.
      + Fix MSVC /RTCc build runtime failures. Patch.

New Libraries

  * No new libraries.

Updated Libraries

  * Asio:
      + Added a deduced trailing return type to all asynchronous operations, to
        enable the new form of async_result for C++11.
      + Moved append, prepend, as_tuple, and deferred to the boost::asio
        namespace, and made them compatible with C++11.
      + Made experimental::parallel_group compatible with C++11.
      + Added buffer() overloads for contiguous containers, such as std::span.
      + Added the ability for awaitable<>-based coroutines to directly co_await
        operations that are packaged as function objects.
      + Changed spawn() to be a completion token-based asynchronous operation,
        and added support for cancellation. The basic_yield_context token now
        supports move-only and variadic result types. When targeting C++11 and
        later, spawn() and basic_yield_context are implemented in terms of
        Boost.Context directly.
      + Added the is_async_operation trait and async_operation concept.
      + Added the completion_signature_of trait.
      + Added converting move construction/assignment to posix descriptors,
        serial ports, pipes, Windows object_handle, Windows stream handles, and
        Windows random-access handles.
      + Added release() member functions to pipes, Windows stream handles, and
        Windows random-access handles.
      + Enabled support for Endpoint implementations that return void pointers
        from their data() member functions, as per the documented Endpoint type
        requirements.
      + Removed all() and race() from experimental::promise, as experimental::
        parallel_group covers this functionality.
      + Added source locations to exceptions and error codes produced by the
        synchronous and asynchronous operations.
      + Fixed compatibility with OpenSSL 3.0.4 and later.
      + Fixed compatibility with with -masm=intel.
      + Explicitly stated that socket shutdown() calls are thread-safe with
        respect to certain other synchronous operations on the same socket.
      + Optimised the move construction of I/O objects where only the executor
        type differs.
      + Fixed the detection of std::invoke_result for clang/libc++.
      + Fixed an issue where experimental::parallel_group initiation
        incorrectly moved arguments instead of forwarding them.
      + Fixed a sequencing issue in the implementation of post(), dispatch(),
        and defer().
      + Fixed the awaitable<> implementation to propagate exceptions from
        awaited initiation functions through the current completion handler.
      + Fixed detection of std::aligned_alloc with gcc 7.
      + Changed to avoid using the soon-to-be-deprecated std::aligned_storage
        on newer compilers.
      + Fixed detection of std::aligned_alloc for older Apple platforms.
      + Removed faulty assertions from experimental::coro implementation.
      + Added defence against Qt-defined macros when building with Intel C++.
      + Changed the implementation of the select_reactor, on Windows, to ensure
        that any exception resulting from failure to recreate its interrupter's
        sockets will be allowed to propagate out through io_context::run().
      + Fixed various compiler warnings.
      + Updated all composed operations examples, and the C++11 timeouts
        example, to use the new async_result form.
      + Added composed operation and coroutine examples for C++20.
      + Consult the Revision History for further details.
  * Atomic:
      + Improved portability of endianness checks on ARM, AArch32 and AArch64
        targets. (#59)
      + Fixed compilation with MSVC 14.0 (Visual Studio 2015) in C++17 mode. (#
        61)
  * Filesystem:
      + On Windows, added a fallback implementation for querying file
        attributes in case if the file cannot be opened with
        ERROR_ACCESS_DENIED error. This may allow status and symlink_status to
        succeed for system files and directories that are not reparse points or
        symlinks. (#234)
      + On Windows, added a workaround for FAT/exFAT filesystems that produce
        ERROR_INVALID_PARAMETER when querying file attributes. This affected
        status and symlink_status, which reported that files do not exist, and
        directory iterators, which failed to construct, as well as other
        dependent operations. (#236, #237)
      + Worked around a compilation problem on RTEMS. (PR#240)
      + On Linux, corrected switching to sendfile copy_file implementation if
        copy_file_range failed with ENOSYS in runtime. The sendfile fallback
        implementation used to skip the filesystem type check and could fail
        for some filesystems.
      + On POSIX systems supporting openat and related APIs defined in
        POSIX.1-2008 and on Windows Vista and later, improved protection of
        remove_all against CVE-2022-21658 that was implemented in the previous
        release. The previous fix could still result in removing unintended
        files in certain conditions. Other systems remain vulnerable.
  * GIL: NOTICE: We are planning BREAKING switch to C++17 as minimum required
    C++ language version in one or two releases after Boost 1.80 (#676)
      + Added
          o GSoC 2020: Added Perona-Malik anisotropic diffusion algorithm (PR#
            500)
          o GSoC 2020: Added histogram class and related functionality (PR#499)
          o GSoC 2020: Added histogram equalization feature (PR#514)
          o GSoC 2020: Added histogram matching algorithm (PR#515)
          o GSoC 2020: Added ability to stack images either horizontally (
            hstack) or vertically (vstack) (PR#506)
          o GSoC 2020: Added adaptive histogram equalization algorithm (PR#516)
          o GSoC 2020: Added Standard Hough Transform and circle rasterization
            (PR#512)
          o GSoC 2020: Added Bresenham's algorithm for line rasterization (PR#
            512)
          o GSoC 2021: Added rotation of image by arbitrary angle around its
            center (PR#565)
          o GSoC 2021: Added rasterization support for ellipse based on "An
            Efficient Ellipse-Drawing Algorithm" by Jerry Van Aken (PR#585)
          o Added image constructor from compatible view (PR#520)
          o Added inverse function for affine matrix3x2 (PR#527)
          o Added standard morphological transformations (PR#541)
          o Added for_each_pixel overload for any_image (PR#648)
          o Added C++17 polymorphic memory resource typedefs for image class (
            PR#529)
      + Changed
          o BREAKING: The required minimum C++ version is changed from from
            C++11 to C++14. Currently, large parts of GIL still compile with a
            C++11 compiler. However, there is no guarantee that it stays that
            way, and any compilers that do not support at least C++14 are
            considered unsupported as of now.
          o BREAKING: any_color_converted_view() is deprecated and will be
            removed in the next release. Use color_converted_view() instead,
            which provides the same feature.
          o BREAKING: apply_operation for any_image is deprecated and will be
            removed in the next release. Use variant2::visit instead, which
            provides the same feature. (PR#656)
          o Moved numeric extension to core (PR#573)
          o Added support for C++17's <filesystem> (PR#636) The availability of
            the std::filesystem is detected automatically, unless the
            BOOST_GIL_IO_USE_BOOST_FILESYSTEM macro is defined that forces the
            preference of the Boost.Filesystem.
          o Renamed pixel_multiply_t to pixel_multiplies_t and pixel_divide_t
            to pixel_divides_t (PR#655)
          o Renamed io/dynamic_io_new.hpp to io/detail/dynamic.hpp (PR#653)
          o Moved function construct_matched into boost::gil::detail namespace
            as it was only used by other implementation details (PR#653)
          o Made packed_pixel trivially copyable and assignable (PR#679)
          o Replace deprecated libtiff v4.3 typedefs with C99 fixed-size
            integers (PR#685)
      + Removed
          o BREAKING: Removed support for GCC 5 (PR#572)
          o Removed deprecated.hpp (PR#627)
      + Fixed
          o Fixed conversion from RGB to HSL (PR#505)
          o Fixed conversion from RGB to signed CMYK (PR#522)
          o Removed unnecessary numeric cast in hsv.hpp (PR#530)
          o Fixed default constructor for homogeneous_color_base for reference
            pixel elements (PR#542)
          o Fixed returning reference to local temporary object in
            subchroma_image_view (PR#556)
          o Added missing header guards in diffusion.hpp (PR#568)
          o Fixed any_image_view<>::const_t (PR#526)
          o Fixed C++20 incompatibilities in I/O extensions (PR#617)
          o Ensured all examples build without errors (PR#628)
          o Fixed convolve_2d for images with float32_t channel model (PR#577)
          o Fixed for_each_pixel for non-1d iterable views (PR#621)
          o Fixed: is_equal_to_sixteen in PNG I/O was less-than test (PR#650)
          o Re-allow devicen_t with two components (PR#654) It was
            unintentionally removed in Boost 1.72
          o Fixed memory leak in image class for empty dimensions (PR#649)
      + Acknowledgements
          o Cypre55, Samuel Debionne, Mike-Devel, Edward Diener, Peter Dimov,
            Omar Emara, Dhruva Gole, Nicolas Herry, Eugene K, Avinal Kumar,
            Gaurav Kumar, Marco Langer, Pranam Lashkari, Mateusz ??oskot,
            Giovanni Mascellani, Debabrata Mandal, Gopi Krishna Menon, Ren??
            Ferdinand Rivera Morell, Felix Morgner, Harshit Pant, Paul92, Andr
            ?? Schr?der, Scramjet911, Siddharth, Dirk Stolle, Prathamesh
            Tagore, theroyn, Olzhas Zhumabek
  * Graph:
      + Bug fixes:
          o Fix bug in stoer_wagner_min_cut where vertices are not merged at
            the end of each mincut phase (#286)
          o Fix conversion warning for return type of strong_components (#293)
          o Fix compilation failure of boykov_kolmogorov_max_flow named
            parameter overload (#232)
      + General code improvements:
          o Remove redundant call to combine in astar_search_no_init_tree (#260
            )
          o Remove redundant child_idx argument of d_ary_heap_indirect<>::child
            (#261)
          o Improve documentation for traversal categories (#303)
      + Acknowledgements
          o Viktor Pti, Sebastian Brockmeyer, Etienne dg
  * Histogram:
      + Fixed segfault in indexed when trying to iterate over histogram with
        axes of zero size (physical or logical) under certain conditions
      + Removed previously deprecated API
          o class accumulators::thread_safe: use accumulators::count<T, true>
          o Methods accumulators::sum::large and accumulators::sum::small: use
            accumulators::sum::large_part and accumulators::sum::small_part
          o Type alias algorithm::reduce_option: use algorithm::reduce_command
          o Template function axis::traits::static_options: use axis::traits::
            get_options
          o Template function axis::traits::static_is_inclusive: use axis::
            traits::is_inclusive
          o Type alias indexed::range_iterator: use indexed::iterator
          o Type alias indexed::accessor::reference: use indexed::accessor::
            const_reference
  * Iterator:
      + For C++11 and later, added support for perfect forwarding of values
        written to function_output_iterator. (PR#73)
      + Added protection against writing to function_output_iterator a result
        of dereferencing another function_output_iterator.
  * JSON:
      + Added non-const value::at overloads.
      + Added the ability to manually choose endianness of the platform.
      + Added string::subview() overload.
      + Fixed segfault in array::erase(it).
      + Fixed low performance of serialize on libc++.
      + Fixed ambigious conversion to std::string_view on GCC 8.
      + Fixed parsing on big-endian platforms.
      + Fixed handling of comment after trailing comma.
  * LEAF:
      + API breaking change: throw leaf::exception(....) now becomes
        leaf::throw_exception(....)
      + Fixed a bug in support for a rare build configuration (exception
        handling enabled, diagnostics disabled)
      + Using nullptr instead of 0 throughout
      + Fixed pedantic warnings
  * Locale:
      + Deprecated support for C++03 and earlier, C++11 will be required in the
        next release
      + Provide -sICU_LINK_LOCALE as a temporary replacement for -sICU_LINK
        which is incompatible with Boost.Regex. -sICU_LINK_LOCALE and -
        sICU_LINK are deprecated and will be replaced by ICU_*_NAME options to
        be compatible with Boost.Regex
      + Fix UB/assertion failure in the ICU collator implementation when
        transforming empty strings
      + Fix some issues related to visibility of classes in shared libraries
        (Unix only)
      + Fix compatibility with C++20 mode
      + Fix compatibility with BOOST_USE_WINDOWS_H
      + Fix build failures due to missing includes
      + Handle or suppress many warnings which makes the build log cleaner
  * Log:
      + Bug fixes:
          o Fixed binding incorrect local address in UDP socket-based
            syslog_backend when IPv6 address is used for the syslog server. (#
            181)
          o Added a workaround for a bug in libstdc++ from gcc 11.2. When
            max_size_decor was used on a formatting stream, std::codecvt::
            do_length incorrectly accessed the input buffer and caused a buffer
            overflow.
      + See changelog for more details.
  * Math:
      + Deprecated C++11 support: from 2023 we will require C++14 as a minimum
        standard. This will mean GCC-5 or MSVC-14.1 as a minimal requirement.
      + Add constexpr fma support, see 734.
      + Add support for the Chatterjee Correlation Coefficient, see 770.
      + Added support for the logarithm of the PDF for all the distributions.
      + Improve support for building with no exception or RTTI support.
      + Some minor bug fixes for [sub 1]F[sub 1] corner cases, see 778.
  * Multiprecision:
      + Mark C++11 support as deprecated: from 2023 we will move to requiring
        C++14 as a minimum standard level. That will drop support for GCC
        versions prior to 5 and MSVC prior to 14.1.
      + Fix conflict between boost/cstdfloat.hpp and this library.
      + Clean up lots of gcc and clang warnings.
      + Fix input streaming of composite types (complex, interval rational)
        where there is a trailing delimeter in the stream and no whitespace.
      + Fix constexpr integer square root where the input is 1, 2 or 3.
      + Add missing #include of <memory> to float128.hpp.
      + Correct 2-arg constructor for class number to prevent ambiguity in some
        cases.
      + Correct and make more consistent behaviour of divide-by-zero in
        gmp.hpp.
  * Multi-index Containers:
      + Maintenance work.
  * Nowide:
      + Major performance improvement for Bulk I/O with files
      + basic_filebuf: Fix wrong return value of sync when fflush failed
      + basic_filebuf: Fix possible undefined behavior in a corner case when
        nothing was actually written but buffer is in "write" mode
      + basic_filebuf: Limit putback of characters (i.e. pbackfail) only
        allowing putback of buffered characters (may be only 1 character)
  * Optional:
      + Added specializations for std::hash<boost::optional<T>>. \ 
This is a
        breaking change for programs that define such specializations
        themselves. For more details see specs.
  * STLInterfaces:
      + Fix #53: "missing 'typename' prior to dependent type name
        'C::const_iterator'"
      + Fix #54: "Concept check fails on .data() of a view on contiguous
        iterator_interface instantiations"
      + New additions to make it easy to write views and view adaptors that
        work like, and interoperate with, the ones in the standard library:
          o Add workalikes for C++23's std::bind_back() and std::
            range_adaptor_closure for pre-C++23 code.
          o Add templates closure and adaptor to make writing view adaptors
            easier, following the examples in P2387.
  * System:
      + When an error_code is converted to std::error_code and then back to
        error_code, the original is now restored, if possible.
      + Reworked the conversion from error_category to std::error_category to
        avoid the one-time allocation that shows up on leak checkers.
      + Added a constructor that allows replacing the source location of an
        error_code, and a corresponding assign.
      + Added a converting constructor to result.
  * Unordered: Major update:
      + Refactor internal implementation to be dramatically faster
      + Allow final Hasher and KeyEqual objects
      + Update documentation, adding benchmark graphs and notes on the new
        internal data structures
  * Utility:
      + In string_view/string_ref, fixed max_size returning incorrect value. (#
        91)
      + Removed noexcept specifier from string_view::compare as it may throw on
        some input arguments. (#94)
      + In string_view/string_ref, added support for calling substr with no
        arguments. (#96)
      + Added string_view::contains methods that were introduced in C++23. (#93
        )
      + In string_view, added asserts in remove_prefix/remove_suffix methods to
        enforce the precondition that the prefix/suffix length does not exceed
        the string view size. The previous (undocumented) behavior of silently
        clamping the prefix/suffix length is deprecated and will be removed in
        a future release. (#92)
  * Wave: Fixed bugs:
      + #24: Line numbers wrong after conditional section
      + #160: one test fails with error C2660 and error C2440 under msvc /
        permissive- mode
      + #161: BOOST_WAVE_THROW_NAME_CTX does not result in a context callback
        and always throws
      + #162: When Boost headers are included in the preprocessed translation
        unit, Wave fails in boost/integer.hpp(99)

Updated Tools

  * Build:
      + Includes release of B2 version 4.9.2.

Version 1.79.0

Known Issues

These are patches from library authors which were found too late to be fixed in
the release.

  * Boost.JSON array::erase can segfault, see #692. Patch.

New Libraries

  * No new libraries.

Updated Libraries

  * Asio:
      + Added bind_allocator.
      + Added file_base::sync_all_on_write flag.
      + Added missing implementation of basic_file::release().
      + Added per-operation cancellation support to signal sets.
      + Exposed recycling_allocator as part of the public interface.
      + Added the nodiscard attribute to a number of functions.
      + Added OpenSSL 3.0 compatibility.
      + Added support for adopting an existing SSL* into an ssl::stream<>.
      + Enabled executor_work_guard<> in all build configurations.
      + Enabled movable socket iostreams when using clang.
      + Fixed bind_cancellation_slot and bind_executor compatibility with
        legacy completion tokens.
      + Fixed associator specialisations for experimental::append and
        experimental::prepend.
      + Fixed associated_allocator primary template.
      + Fixed io_uring implementations of async_receive_from for sockets and
        write_some_at for files.
      + Fixed io_uring feature detection.
      + Fixed experimental::coro's per-operation cancellation.
      + Fixed memory management in experimental::promise's type-erased
        completion handlers.
      + Fixed move operator= implementation for ssl::stream.
      + Fixed any_io_executor implementation to work when both
        BOOST_ASIO_USE_TS_EXECUTOR_AS_DEFAULT and
        BOOST_ASIO_SEPARATE_COMPILATION are defined.
      + Fixed implementation of basic_socket::at_mark() when using the
        sockatmark() system call.
      + Changed the recycling allocator to use the default alignment as the
        minimum alignment for allocations.
      + Added a workaround for apparent coroutine codegen bug with Apple's
        clang.
      + On Windows, changed the file support to open files using the same
        sharing mode as fopen().
      + On Linux, fixed UNIX domain sockets implementation to correctly handle
        EAGAIN.
      + Fixed implementation of experimental::basic_channel::reset() and
        experimental::basic_concurrent_channel::reset().
      + Fixed potential undefined behaviour in the experimental::promise.
      + Changed the co_spawn implementation to dispatch cancellation signals
        through the executor in some circumstances.
      + Fixed various header inclusion issues.
      + Fixed various warnings.
      + A number of documentation enhancements, including:
          o Added an overview of Asio's asynchronous model.
          o Reworked reference and requirements documentation in terms of
            asynchronous model.
          o Updated documentation for dispatch(), post(), and defer().
          o Documented per-operation cancellation for serial ports.
          o Clarified the non-concurrency guarantees made for allocators.
          o Reverted the io_context reference documentation to use
            executor_work_guard.
          o Added more detailed reference documentation to make_strand(),
            make_work_guard(), ip::address_v4, ip::address_v6, experimental::
            basic_channel, and experimental::basic_concurrent_channel.
          o Re-arranged and extended the Overview documentation to cover
            recently added features.
      + Added a C++11 example showing file descriptor passing over local
        sockets.
      + Added C++14 examples of wrapping callback-based APIs in asynchronous
        operations.
      + Consult the Revision History for further details.
  * Assert:
      + source_location().file_name() and source_location().function_name() now
        return "" instead of "(unknown)".
      + Added a source_location constructor from std::source_location.
      + Changed BOOST_CURRENT_LOCATION to more closely match the behavior of
        std::source_location::current(), such as being usable at top level or
        as a default function argument.
  * Atomic:
      + Fixed compilation for Universal Windows Platform (UWP). (#54)
      + Added BOOST_ATOMIC_NO_DARWIN_ULOCK configuration macro. The macro
        affects compilation on Darwin systems and disables ulock-based
        implementation of waiting and notifying operations. This may be useful
        to comply with Apple App Store requirements. (#55)
  * Beast:
      + Added missing include for file_body test.
      + Fixed WebSocket handshake response on failure.
      + Fixed open append mode for file_posix and file_win32.
      + Fixed file open with append/append_existing flag on Windows
      + Fixed clang-cl UTF8 path handling for file_win32 and file_stdio.
      + Added ARM64 builds to drone CI.
      + Fixed async_base documentation link.
      + Added tests for file open in append/append_existing mode.
      + Updated CI to include gcc 11, clang 12, msvc 14.3.
      + Added individual tests to CMake workflow.
      + We'd love to know how you or your company use Beast, consider adding an
        entry to the Companies and Individuals Using Beast list.
      + See the full Release Notes for a complete list of changes.
  * Core:
      + Made boost::pointer_traits SFINAE friendly, addressing LWG3545. (Glen
        Fernandes)
      + Added boost::allocator_traits that uses the individual allocator access
        traits. This implementation supports C++03 and above. (Glen Fernandes)
      + Updated the allocator access traits to support most of the C++11
        allocator model in C++03. (Glen Fernandes)
      + boost/iterator.hpp is deprecated and will be removed in a future
        release. The header defines boost::iterator template, which is
        equivalent to std::iterator in <iterator> header. However, since std::
        iterator is itself deprecated in C++17, users are advised to remove
        boost::iterator or std::iterator use from their code.
      + Added boost::core::verbose_terminate_handler, a utility function
        intended to be passed to std::set_terminate that prints information
        about the uncaught exception to stderr.
  * Describe:
      + Enabled unions in BOOST_DESCRIBE_STRUCT and updated examples to check
        std::is_union<T>.
      + Added example of defining a fmtlib class formatter.
      + Added example of defining a fmtlib enum formatter.
      + Added example of printing pointers to members.
  * Filesystem:
      + v3: path::replace_extension now works in terms of v3 definition of path
        ::extension rather than v4.
      + Fixed compilation of path appending and concatenation operators with
        arguments of types convertible to path or compatible string type. (#223
        )
      + On POSIX systems that support fdopendir and O_NOFOLLOW and on Windows,
        remove_all is now protected against CVE-2022-21658. The vulnerability
        is a race condition that allows a third party process to replace a
        directory that is being concurrently processed by remove_all with a
        directory symlink and cause remove_all to follow the symlink and remove
        files in the linked directory instead of removing the symlink itself. (
        #224)
      + On Windows, in remove and remove_all implementation, use POSIX
        semantics for file removal, when supported by the OS (Windows 10 1709
        and later). When POSIX semantics is supported, the file name is removed
        from the filesystem namespace as soon as the file is marked for
        deletion, even if it is still open and in use. With legacy Windows
        semantics, the file name remains present in the the filesystem
        namespace until the last file handle to the file is closed, which
        allows the file marked for deletion to be opened and prevents creating
        new files with the same name. (#216)
      + On Windows, remove and remove_all now support deleting read-only
        directories. Support for removing read-only non-directory files was
        added previously.
      + On Windows, directory_iterator internal implementation has been
        reworked to better utilize modern Windows APIs, which may improve
        performance while handling symlinks.
      + On Windows, initialize internal WinAPI function pointers early, if
        possible, to allow Boost.Filesystem operations to be invoked in global
        constructors. This is only supported on MSVC, GCC, Clang and compatible
        compilers.
      + On Windows, resize_file should no longer fail with an error if the file
        to be resized is opened.
      + Disabled use of the statx syscall on Android prior to 11.0 (API version
        30). The syscall is blacklisted by seccomp and causes process
        termination in runtime. (#229)
      + Deprecated: boost/filesystem/string_file.hpp header is deprecated and
        will be removed in a future release. The header is no longer included
        by boost/filesystem.hpp by default. Users are advised to implement the
        functionality themselves or migrate to other implementations.
      + Deprecated: Windows CE support is deprecated and will be removed in a
        future release. Windows CE has been untested for many years and is
        likely non-functional.
  * Geometry:
      + Major change
          o PR#977 Rescaling is turned off by default. This avoids many related
            bugs in set operations and buffer.
      + Improvements
          o PR#923 Added algorithm closest_points for cartesian point/geometry.
          o PR#939 Added algorithm closest_points for other coordinate systems
            and geometry combinations excl. boxes.
          o PR#961 Added Web Mercator projection.
          o PR#966 More efficient cartesian distance strategy used in simplify.
      + Solved issues
          o #956 Result of simplify algorithm with incorrect closure.
          o #962 Runtime error in R-tree deserialization due to load factor.
          o #971 R-tree insertion time impacted by use of long double on ARM
            platforms.
      + Bugfixes
          o PR#936 Envelope of polygon containing pole.
          o PR#948 Spherical and geographic envelope for near meridian
            segments.
          o PR#974 Spheroidal normalization utilities for NaN coordinates.
          o Various fixes in set operations and buffer.
  * Integer:
      + Optimized integer_log2 implementation to use bit operations internally.
        This allows to employ bit instructions available on most modern CPUs. (
        #31)
  * IO:
      + Added boost::io::basic_nullbuf, a null stream buffer, and boost::
        basic_onullstream, a null output stream (Glen Fernandes).
  * Iterator:
      + In counting_iterator, added support for built-in 128-bit integer types
        supported by gcc and clang and compatible compilers on some target
        platforms.
      + Silenced gcc warnings about deprecated implicit copy assignment
        operator in counting_iterator.
  * JSON:
      + Standalone mode of the library is removed. Users who wish to continue
        using standalone JSON can switch to the C++ Alliance fork.
      + Add std::error_code overloads.
      + Add boost::source_location to error_codes.
      + Add support for JSON Pointer.
      + Naturally grow string during serialization.
  * LEAF:
      + Support for FreeRTOS and other embedded platforms
      + Improved diagnostic information
      + Improved configuration macros
      + BOOST_LEAF_CHECK using statement expressions under __GNUC__
      + Fixed symbol demangling bug
  * Log:
      + General changes:
          o In text_file_backend, added support for appending to a previously
            written log file, when file rotation is used and log file names use
            file counters.
          o Breaking change: The file_collector interface has changed:
              # scan_for_files method returns a scan_result structure that
                contains information collected during the scan;
              # is_in_storage method added for testing if a path refers to a
                file within the target storage directory.
          o Added a new invoke_manip stream manipulator that can be used for
            injecting user's function into a stream output expression.
      + Bug fixes:
          o Fixed file counter being set to zero if the user calls
            text_file_backend::scan_for_files multiple times, and the second
            and the following calls don't find any new files. (#179)
      + See changelog for more details.
  * Multi-index Containers:
      + Improved the efficiency of count operations in ranked indices from O(
        log(n) + count) to O(log(n)). Contributed by Damian Sawicki.
      + Maintenance work.
  * Nowide:
      + Fix compilation issues on some platforms (e.g. GCC 11 on MinGW-w64 and
        Cygwin)
      + Fix missing include when using BOOST_USE_WINDOWS_H and
        WIN32_LEAN_AND_MEAN
      + Add sanity check when using boost::nowide::stat with boost::nowide::
        stat_t
  * Optional:
      + Fixed issue #98.
      + Fixed issue #92.
      + Added support for BOOST_NO_IOSTREAM.
      + Now aligned storage uses unsigned char rather than char to avoid UB.
      + Now using cv-unqualified value_type with placement new to avoid UB.
  * Predef:
      + Version 1.14.0
      + Add detection of LoongArch (from Zhang Na).
  * QVM:
      + Added constexpr under C++17
      + Improved single header distribution
  * Smart Pointers:
      + Added boost::get_allocator_pointer to obtain the Allocator pointer from
        the result of boost::allocate_unique (Glen Fernandes).
  * System:
      + Added a boost::source_location parameter to throw_exception_from_error.
      + Added throw_exception_from_error overloads for errc::errc_t, std::
        error_code, std::errc, std::exception_ptr.
      + result<T>::value now automatically supplies BOOST_CURRENT_LOCATION to
        throw_exception_from_error via a default argument.
      + Added an errc::make_error_code overload taking a source location.
  * ThrowException:
      + Added boost::throw_with_location, a more lightweight alternative of
        BOOST_THROW_EXCEPTION for programs that do not use Boost.Exception.
  * Unordered:
      + All containers have been updated to support heterogeneous count,
        equal_range and find.
      + All containers now implement the member function contains.
      + erase_if has been implemented for all containers.
      + All containers have been updated to support heterogeneous erase and
        extract.
      + Changed behavior of reserve to eagerly allocate.
      + Various warning fixes in the test suite.
      + Update code to internally use boost::allocator_traits.
      + Switch to Fibonacci hashing.
      + Update documentation to be written in AsciiDoc instead of QuickBook.
  * Variant2:
      + Added operator<< for monostate.
  * Wave:
      + C++11 now required for building Wave itself
      + Fixed bugs:
          o #135: Comma operators in array subscripts are deprecated in C++20
          o #137: Simple unknown directive => found_unknown_directive is not
            called, stripped of pound.
          o #138: Empty ifdef block does not emit line directive for missing
            whitespace
          o #143: Parsing __has_include() fails with trailing tokens
          o #145: Sanitizer complains about reset_version()
          o #147: bitwise operations between different enumeration types are
            deprecated

Updated Tools

  * Build:
      + Includes release of B2 version 4.8.2.

Log message:
boost: Update to 1.78.0

Changelog:
Version 1.78.0

Known Issues

These are patches from library authors which were found too late to be fixed in
the release.

  * Boost.Build silently skips installation of library headers and binaries in
    some cases, see #104.
      + Fixed in PR#113, patch.
  * Boost.Atomic fails to build when targeting UWP, see #54. Patch.

New Libraries

  * No new libraries.

Updated Libraries

  * Asio:
      + Added an io_uring backend that may optionally be used for all I/O
        objects, including sockets, timers, and posix descriptors.
      + Added support for files, with new new classes for stream-oriented and
        random-access files. This feature currently supports I/O completion
        ports on Windows, and io_uring on Linux.
      + Added support for portable pipes on POSIX and Windows (when I/O
        completion ports are available).
      + Added support for registered buffers, which are optimised when using
        the io_uring backend.
      + Added experimental support for channels, that may be used to send and
        queue completions as messages.
      + Implemented improvements to experimental::coro.
      + Disabled aligned_alloc on clang when using an MSVC runtime.
      + Changed to use a faster implementation for ip::network_v4::canonical().
      + Added template specialisations for common uses to improve compile time.
      + Reduced the size of io_context executors to a single pointer.
      + Increased the small object buffer size for execution::any_executor and
        any_io_executor.
      + Fixed multi-signature handling when variadic templates are disabled.
      + Fixed compatibility with new versions of gcc and clang.
      + Fixed compilation on Solaris.
      + Fixed defence against Qt-defined macros when building with MSVC.
      + Improved error messages emitted by ssl facilities.
      + Fixed bind_executor compatibility with completion tokens.
      + Fixed build errors when BOOST_ASIO_USE_TS_EXECUTOR_AS_DEFAULT is
        defined.
      + Added missing move assignment operator to awaitable<>.
      + Fixed an access violation when using coroutines with MSVC, due to
        incorrect alignment of allocated memory.
      + Fixed a cleanup issue in experimental::parallel_group that occured when
        the execution context was shut down with parallel operations still
        pending.
      + Added clarifications to the documentation on concurrency hints.
      + Added documentation on error handling techniques for C++20 coroutines.
      + Fixed various warnings.
      + Consult the Revision History for further details.
  * Assert:
      + Added source_location::to_string.
  * Atomic:
      + Use process-local futex operations on Android for non-IPC waiting and
        notifying operations.
      + Added support for Linux targets that only define SYS_futex_time64
        syscall, such as riscv32.
      + Added a workaround for incorrect result of std::alignment_of on clang 8
        for 64-bit types on 32-bit x86 targets.
      + Added a ulock backend for waiting and notifying operations on Darwin
        systems since Mac OS 10.12, iOS 10.0, tvOS 10.0 or watchOS 3.0.
      + On Windows, corrected discrepancy between atomic-type
        ::always_has_native_wait_notify and the corresponding capability macros
        when targeting Windows 8 or later. The library will now directly use
        WaitOnAddress and related APIs from public headers and therefore
        require user to link with synchronization.lib if the user requires
        Windows 8 or later by defining BOOST_USE_WINAPI_VERSION, _WIN32_WINNT
        or similar macros. The library is linked automatically on compilers
        that support auto-linking (e.g. MSVC).
      + Added support for types with padding bits, except unions, on compilers
        that provide a way to clear the padding bits. This feature is supported
        by gcc 11 and MSVC 14.2 (compiler version 19.27) and newer, as well as
        other compilers supporting similar intrinsics. On compilers that don't
        allow to clear the padding bits, types with padding are still generally
        not supported with the exception of 80-bit long double on x86 targets.
        A new BOOST_ATOMIC_NO_CLEAR_PADDING capability macro is defined to
        indicate when clearing the padding is not supported.
      + Initializing constructors of atomic_ref and ipc_atomic_ref no longer
        use atomic instructions to clear the padding bits in the referenced
        object. This reduces the cost of the atomic reference construction.
      + Initializing constructors of atomic and ipc_atomic are now constexpr
        for enums, classes and floating point types. For classes and floating
        point types, the constructors are constexpr if the compiler supports
        constexpr std::bit_cast, the type has no padding bytes and no padding
        is required to implement native atomic operations.
      + In accordance with C++20, default constructors of atomic and ipc_atomic
        now perform value initialization of the contained object. For types
        without a user-defined default constructor, this means the
        default-constructed atomic will be zero-initialized.
      + Added a workaround for compilation error on AIX caused by the assembler
        tool not supporting numeric labels. (PR#50)
      + Added a workaround for compilation error with Visual Studio 2015 prior
        to Update 3. (#52)
      + See changelog for more details.
  * Beast:
      + This maintenance update brings minor bug fixes and updated CI
        reporting.
      + Fixed security vulnerability CVE-2016-9840 in zlib implementation.
      + Fixed WebSocket permessage_deflate implementation. This should result
        in an increase in compression performance when using Beast WebSockets.
      + Removed the test stream and test framework's dependency on RTTI. You
        can now use our handy test stream to check your embedded asynchronous
        communications code!
      + We'd love to know how you or your company use Beast, consider adding an
        entry to the Companies and Individuals Using Beast list.
      + See the full Release Notes for a complete list of changes.
  * Core:
      + Added a generic implementation to <boost/core/cmath.hpp>, enabled when
        BOOST_CORE_USE_GENERIC_CMATH is defined or when the platform does not
        provide the necessary facilities in <cmath>.
      + Added boost::core::type_name, a utility function that returns the name
        of a type as a string.
      + Added boost::span, a C++11 implementation of C++20's std::span (Glen
        Fernandes).
  * Describe:
      + Added has_describe_enumerators, has_describe_bases,
        has_describe_members.
      + Added enum_to_string, enum_from_string.
      + Added relational and stream insertion operators.
      + Added descriptor_by_name, descriptor_by_pointer.
  * DLL:
      + Fixed missing #include, thanks to Denis Blank (PR#54)
      + Dropped TravisCI in favor of GithubAction CI
  * Filesystem:
      + v4: path::filename and path::iterator no longer return an implicit
        trailing dot (".") element if the path ends with a directory \ 
separator.
        Instead, an empty path is returned, similar to C++17 std::filesystem.
        This also affects other methods that are defined in terms of iterators
        or filename, such as path::stem, path::compare or
        lexicographical_compare. For example, path("a/b/") == \ 
path("a/b/.") no
        longer holds true. (#193)
      + v4: path::lexically_normal no longer produce a trailing dot (".")
        element and omits a directory separator after a trailing dot-dot \ 
("..")
        element in the normalized paths.
      + v4: path append operations now consider root name and root directory in
        the appended path. If the appended path is absolute, or root name is
        present and differs from the source path, the resulting path is
        equivalent to the appended path. If root directory is present, the
        result is the root directory and relative path rebased on top of the
        root name of the source path. Otherwise, the behavior is similar to v3.
        (#214)
      + path::lexically_normal now converts directory separators to preferred
        separators in the root name of the normalized paths.
      + Optimized overloads of path::assign, path::append, path::concat and the
        corresponding operators to avoid unnecessary path copying and reduce
        the amount of code redundancy.
      + On POSIX systems, fixed absolute(p, base) returning a path with root
        name base.root_name() if p starts with a root directory. In such a case
        p is already an absolute path and should be returned as is.
      + create_directories no longer reports an error if the input path
        consists entirely of dot (".") and dot-dot ("..") \ 
elements. The
        implementation is no longer using recursion internally and therefore is
        better protected from stack overflow on extremely long paths.
      + On Windows, remove now supports deleting read-only files. The operation
        will attempt to reset the read-only attribute prior to removal. Note
        that this introduces a possibility of the read-only attribute being
        left unset, if the operation fails and the original value of the
        attribute fails to be restored. This also affects remove_all. (#216)
      + remove_all now returns static_cast< uintmax_t >(-1) in case of error,
        similar to C++17 std::filesystem.
      + Fixed a linking error about unresolved references to
        Boost.ContainerHash functions when user's code includes boost/
        filesystem/path.hpp but not boost/container_hash/hash.hpp and the
        compiler is set to preserve unused inline functions. (#215)
      + Added a workaround for MSVC and compatible compilers eliminating path
        globals cleanup in release builds. This could lead to a memory leak if
        Boost.Filesystem shared library was repeatedly loaded and unloaded in
        the process. (#217)
  * Geometry:
      + Improvements
          o PR#894 Optimization and refactoring of rtree queries.
          o PR#913 DynamicGeometry and GeometryCollection support in various
            algorithms (undocumented for now).
          o PR#922 DynamicGeometry and GeometryCollection support in distance
            (undocumented for now).
      + Solved issues
          o #867 Poor performance of rtree query iterator with nearest
            predicate for big k.
          o #870 Compilation error in boost::geometry::self_turns.
          o #896 Assertion failure in get_turns with
            BOOST_GEOMETRY_NO_ROBUSTNESS.
      + Bugfixes
          o PR#906 Invalid result of buffer on macos-11 with clang-12.
          o PR#921 Compilation errors with c++20 (various compilers) and gcc-5.
          o Various fixes in set operations and buffer.
  * JSON:
      + Standalone mode of the library is deprecated.
      + Allow external libraries to forward declare value_to and value_from.
      + Fixed signed integer overflow in number parsing.
      + Add support for /Zc:implicitNoexcept- on MSVC.
  * Lambda2:
      + Added special cases in operator<< and operator>> when the first
        argument is a stream, to allow std::cout << _1.
      + Added operator->*.
      + Added first, second.
  * Log:
      + General changes:
          o Updated detection of std::codecvt specializations for char16_t and
            char32_t for compatibility with C++17 and later. (PR#159)
          o Added support for C++17 std::byte type to receive methods of the
            inter-process message queue.
          o On Windows, when building the library for Windows 8 or later, the
            library will use nt62 tag in the version namespace to denote the
            target OS ABI. For example, the version namespace could be named as
            v2_mt_nt62. This name will be part of all symbols exported by the
            library. Use the BOOST_USE_WINAPI_VERSION macro consistenly when
            building Boost and your code to request the minimum target Windows
            version.
          o Improved performance of SSSE3 and AVX2 implementations of the dump
            stream manipulator.
          o Added support for CMake build system. Only library build is
            supported at this moment, Boost.Build is still used for running
            tests.
      + Bug fixes:
          o Fixed a race condition on POSIX systems in reliable_message_queue::
            open_or_create or the equivalent constructor. Multiple threads or
            processes calling open_or_create concurrently with sending or
            receiving messages from the same queue could end up corrupting the
            queue contents and potentially crashing the process. (#162)
          o Added a workaround for b2 install failing on Windows because of
            missing boost_log_setup library if
            BOOST_LOG_WITHOUT_SETTINGS_PARSERS is defined. (#164)
      + See changelog for more details.
  * Math:
      + Add support for cubic roots.
      + Add support for constexpr versions of various standard library math
        routines.
      + Add support for Bezier polynomials.
      + Improve worst-case tanh-sinh integration performance.
      + Disable inadvertant use of integral types in integration routines.
      + Minor update for erf approximations when the result is with 2ulp of 1.
      + Allow Bernoulli code to be used on platforms with no atomic integers.
      + Improve the mode of the non-central Chi Squared distribution.
      + Improve certain edge cases for <cstdfloat> complex-valued elementary
        functions, see #507.
  * Multi-index Containers:
      + Added contains to key-based indices (issue #35).
      + Added merge operations to key-based indices. The functionality goes
        beyond the standard specification for (unordered) associative
        containers in a number of ways, most notably:
          o The source index can be of any type, including non key-based
            indices.
          o Partial merge is provided: for instance, x.merge(y,first,last)
            merges only the elements of y within [first,last).
      + Previous versions of splice for sequenced and random access indices
        were destructive, i.e. elements were copy-inserted into the destination
        and then erased from the source. Now, splice is based on node transfer
        much as merge in key-based indices, and has been similarly extended to
        accept source indices of any type: in fact, splice can be regarded as a
        frontend to the same functionality provided by merge in key-based
        indices. For reasons of backwards compatibility, the destructive
        behavior of splice has been retained in the case that the source and
        destination containers have unequal allocators.
      + The fact has been documented that index iterator types do only depend
        on node_type and the position of the index in its multi_index_container
        , (except for hashed indices, where uniqueness/non-uniqueness is also a
        dependency). This has implications on the validity of iterators to
        elements transferred by merge or splice. This property is a variant of
        what has been called SCARY iterators in the C++ standard mailing lists.
        SCARYness is currently (August 2021) not mandated for standard
        containers.
      + Iterator SCARYness is now also preserved in safe mode.
  * Multiprecision:
      + Rework rational_adaptor to remove dependency on Boost.Rational and
        improve performance.
      + Fix issue with type_traits and clang, see #383.
      + Fixed buggy Lehmer's GCD routine, see #370.
      + Fix mpc_complex constructors so that lossy conversions are explicit,
        see #363.
      + Correct miscellaneous configuration issues (Intel intrinsic usage and
        Apple clang).
      + Correct some iostream operators for unsigned char types.
      + Correct mpq_rational conversions to integer types, see #342.
  * PFR:
      + Added missing #include <memory> for inclusion of std::addressof
      + Fixed -Wzero-length-array warning when dealing with empty aggregates
      + Fixed compilation on msvc compilers <= 1920 (thanks to Alexey Romanov
        aka @alexey-romanov)
      + Added basic CMakeLists.txt support (thanks to @pdimov aka Peter Dimov)
      + Multiple improvements for docs, including links to https://github.com/
        apolukhin/pfr_non_boost
      + Added misc/strip_boost_namespace.sh script to remove boost:: and BOOST_
        prefixes
  * Predef:
      + Version 1.13.1
      + Fix spelling of "epoch".
      + Add missing parenthesis in sparc.h (from tkoecker).
      + Update documentation to use Rouge code styling and Amber general style.
  * Regex:
      + Breaking Change: Change \B to be the opposite of \b as per Perl
        behaviour.
      + Change w32_regex_traits.hpp so that windows.h is no longer included.
      + Fxed fuzzing related issues #151, #152, #153, #156.
  * System:
      + Added support for source locations to error_code.
      + Added error_code::to_string, error_condition::to_string, error_code::
        what.
      + system_error::what() now contains the source location, if present.
      + Added result<T, E = error_code>, a class holding either a value or an
        error, defined in <boost/system/result.hpp>.
  * Utility:
      + Library documentation converted to QuickBook (thanks to Alan de
        Freitas, PR#79).
  * Variant2:
      + Added <boost/variant2.hpp>.
      + Added unsafe_get<I>.
      + Added visit_by_index.
      + Added operator<<.

Updated Tools

  * Build:
      + Includes release of B2 version 4.7.2.

Log message:
boost: updated to 1.77.0

1.77.0

New Libraries
Describe:
A C++14 reflection library, from Peter Dimov. Provides macros for describing \ 
enumerators and struct/class members, and primitives for querying this \ 
information.
Lambda2:
A C++14, dependency-free, single header lambda library, from Peter Dimov. Allows \ 
simple function objects to be constructed via expressions such as _1 + 5, _1 % 2 \ 
== 0, _1 > _2, or _1 == ' ' || _1 == '\t'.
Updated Libraries
Any:
Added boost::anys::basic_any - a data type with customizable Small Object \ 
Optimization whose instances can hold instances of any type that satisfies \ 
ValueType requirements (many thanks to Ruslan Arutyunyan @rarutyun). If you are \ 
not sure that you really need it, then use boost::any instead.
Started using GithubActions CI for additional testing
Asio:
Added support for cancellation of individual asynchronous operations.
Added the associator trait, used to generically forward associators.
Changed all asynchronous operations implemented in Asio to invoke their \ 
completion handlers as rvalue references.
Added support for asynchronous operations with multiple completion signatures.
Added operator&& and operator|| for awaitable<>, to allow \ 
coroutines to be trivially awaited in parallel.
Added the experimental::as_tuple completion token adapter.
Added the experimental::append completion token adapter.
Added the experimental::prepend completion token adapter.
Added the experimental::deferred completion token, whicih allows deferred \ 
execution of asynchronous operations.
Added the experimental::parallel_group class and \ 
experimental::make_parallel_group function.
Added experimental::promise, which allows eager execution and synchronisation of \ 
asynchronous operations.
Added the experimental::coro class template, a C++20 coroutine primitive with \ 
the ability to combine both asynchronous waiting (co_await) and yielding \ 
(co_yield).
Added move assignment to ssl::stream<>.
Changed co_spawn to dispatch the coroutine's initial step to the executor.
Enabled additional optimisations for any_executor and any_io_executor when used \ 
with asynchronous operations.
Added the nodiscard attribute to awaitable<>.
Increased the number of cached slots in the default recycling allocator.
Changed the default allocator behaviour to respect alignment requirements, to \ 
support over-aligned types.
Ensured the result strings are always initialised in reverse name resolution.
Fixed recursive template instantiation issues in \ 
use_awaitable_t::executor_with_default.
Fixed the any_io_executor equality operators to correctly return a result based \ 
on the target executor.
Fixed strand<> to avoid using a potentially moved-from executor.
Ensured gcc tests are not used for clang when detecting compiler features.
Disabled coroutines support for the clang shipped with MSVC.
Fixed compatibility with recent LibreSSL when OPENSSL_NO_SSL_INTERN is defined.
Fixed posix::basic_stream_descriptor move operations to work with non-defaulted \ 
executors.
Consult the Revision History for further details.
Atomic:
Added make_atomic_ref and make_ipc_atomic_ref factory functions for constructing \ 
atomic reference objects.
Added C++17 template argument deduction guides for atomic_ref and ipc_atomic_ref \ 
to allow omitting template arguments when they can be deduced from constructor \ 
arguments.
Beast:
This maintenance update brings minor bug fixes and updated CI reporting.
We'd love to know how you or your company use Beast, consider adding an entry to \ 
the Companies and Individuals Using Beast list.
See the full Release Notes for a complete list of changes.
Conversion:
boost::implicit_cast is now constexpr.
Fixed broken links.
Started using GithubActions CI for additional testing
Core:
boost/core/uncaught_exceptions.hpp has been modified for compatibility with Mac \ 
OS 10.4 and older.
DLL:
More runtime checks for malformed ELFs in boost::dll::library_info
In boost::dll::library_info use info from .dynsym ELF section if .symtab is \ 
empty or missing
List protected ELF symbols in boost::dll::library_info as they are available for \ 
import
Remove unneeded convert from wchar_t to char on POSIX environment, thanks to \ 
Vladislav Shchapov
Started using GithubAction CI for additional testing
Filesystem:
Introducing Boost.Filesystem v4. This new version of the library removes all \ 
deprecated features of v3 and also makes a number of breaking API changes \ 
intended to make Boost.Filesystem more compatible with std::filesystem \ 
introduced in C++17. The differences are described in the release notes and \ 
documentation using v3 and v4 tags and are also summarised in a separate \ 
section. Users can select Boost.Filesystem version by defining \ 
BOOST_FILESYSTEM_VERSION macro to either 3 or 4 when compiling their code. There \ 
is no need to separately compile Boost.Filesystem for each library version - a \ 
single binary supports both v3 and v4. Users should avoid using both v3 and v4 \ 
in the same application as this can lead to subtle bugs. Currently, v3 is the \ 
default. In a future release v4 will become the default, and eventually v3 will \ 
be removed. v4 is functional, but it is still a work in progress and there may \ 
be breaking API changes in the future.
v4: path::filename, path::stem and path::extension no longer consider root name \ 
or root directory of the path as a filename if the path only consists of those \ 
components. For example, on Windows path("C:").filename() used to \ 
return "C:" and path("C:\\").filename() used to return \ 
"\" and both will return an empty path now.
v4: path::stem and path::extension no longer treat a filename that starts with a \ 
dot and has no other dots as an extension. Filenames starting with a dot are \ 
commonly treated as filenames with an empty extension. The leading dot is used \ 
to indicate a hidden file on most UNIX-like systems.
New: Improved support for various path prefixes on Windows. Added support for \ 
local device prefix ("\\.\") and experimental support for NT path \ 
prefix ("\??\"). The prefixes will be included in the root name of a \ 
path. Note that using the prefixes with Boost.Filesystem v3 can lead to \ 
surprising results (e.g. path("\\\\.\\").stem() == "\\\\"). \ 
It is recommended to use the prefixes only with Boost.Filesystem v4.
Reworked path::lexically_normal implementation to eliminate some cases of \ 
duplicate dot (".") elements in the normalized paths.
New: Added runtime detection of the statx and getrandom system calls on Linux. \ 
This can be useful if the syscall is present at compile time but fails with \ 
ENOSYS at run time (for example, in Docker containers that restrict the syscall, \ 
even if available on the host).
New: Added support for disabling usage of various system APIs at library build \ 
time. This can be useful when a certain API is detected as present by the \ 
library configuration scripts but must not be used for some reason (for example, \ 
when runtime detection does not work on the target system). See the description \ 
of configuration macros in the library documentationfor for more details.
New: Added copy_options::synchronize_data and copy_options::synchronize options \ 
for the copy_file operation. These options allow to synchronize the written data \ 
and attributes with the permanent storage. These options are expensive in terms \ 
of performance, but allow to ensure reliability of the copied data. Note that \ 
copy_file performed implicit data synchronization on POSIX systems since \ 
Boost.Filesystem 1.74.0. This release adds support for more platforms and \ 
disables data synchronization by default while allowing the caller to explicitly \ 
request it.
Added handling of EINTR error code on POSIX systems for some system calls issued \ 
internally. In particular, EINTR could have been ignored on close, which on \ 
HP-UX would result in a leaked file descriptor.
In the copy_file implementations based on Linux sendfile and copy_file_range \ 
system calls, added handling of error codes indicating that a particular \ 
filesystem does not support the system call and fall back to the generic \ 
read/write loop. This should fix copy_file failing on eCryptFS and possibly \ 
other filesystems.
The copy_file_range system call is now used since Linux kernel 4.5, whereas \ 
previously it was only enabled since 5.3. The copy_file implementation will fall \ 
back to sendfile or read/write loop if copy_file_range fails to copy a given \ 
file across filesystems.
The copy_file implementations based on Linux sendfile and copy_file_range system \ 
calls will not be used on filesystems that are known to contain files with \ 
generated content. These system calls are incompatible with such files, and \ 
copying them would result in zero-sized files. The generic read/write loop will \ 
be used instead. Currently, the blacklisted filesystems are: procfs, sysfs, \ 
tracefs and debugfs.
In the copy_file implementation based on read/write loop, increased the maximum \ 
size of the buffer used for temporary storage and take into account the target \ 
filesystem block size for more optimal performance.
On Windows CE, calling current_path to obtain the current path for a process \ 
will now fail with an error instead of returning successfully with a root path. \ 
This platform does not support current directory. Changing the current path was \ 
already failing similarly in previous releases of Boost.Filesystem.
In canonical, fixed the check for a symlink referencing a directory above root, \ 
if an earlier symlink was resolved to an absolute path with a different root \ 
from the original path.
In canonical, added a limit for the maximum number of symlinks that can be \ 
resolved during the call. The limit is currently at least 40 symlinks.
On Windows, canonical and weakly_canonical will now use \ 
path::preferred_separator for the root directory separator in the resulting \ 
paths. This fixes "file not found" errors caused by Windows API not \ 
handling generic separators in UNC paths and paths that start with the Win32 \ 
filesystem prefix ("\\?\").
New: Added weakly_canonical overloads taking base path as an argument.
On Windows, weakly_canonical no longer fails with an error if the input path \ 
contains elements that do not exist in the filesystem but are cancelled by a \ 
subsequent dot-dot ("..") element. For example, \ 
weakly_canonical("C:\\a\\..") would previously fail if \ 
"C:\a" directory did not exist.
In read_symlink on Windows, corrected reparse point handling. The operation \ 
would return an empty path for some mount points (for example, created by Box \ 
cloud storage driver) and directory junction points that had empty print names. \ 
The new implementation now parses substitute name of the reparse point and \ 
attempts to reconstruct a Win32 path from it.
On Windows, file streams provided in boost/filesystem/fstream.hpp will use wide \ 
character paths on libc++ versions 7.0 and higher, when the standard library \ 
supports opening files with wide character paths.
On Windows, creating symlinks should no longer require elevated privileges, if \ 
Windows is configured in Developer mode.
With some compilers, global objects used internally in Boost.Filesystem are now \ 
destroyed after user's global destructors are called. This allows to call \ 
Boost.Filesystem methods during the program termination stage. In particular, \ 
this concerns the path locale that is used for character code conversion and can \ 
be installed by calling path::imbue. The supported compilers include MSVC, GCC \ 
and Clang, as well as other compilers that support customizing program \ 
initialization order through #pragma section (for MSVC-compatible compilers) or \ 
__attribute__ ((init_priority)) (for GCC-compatible compilers).
JSON:
value_to supports TupleLike types.
value_to and value_from support std::array and similar types.
Implicit conversion operator from string to std::string_view.
std::hash specializations for json types.
Fixed allocation errors in object and key_value_pair.
Fixed crash when constructing array from a pair of iterators that form an empty \ 
range.
LexicalCast:
Fixed assignment to an int of a floating point value that is out of \ 
representable range for int.
Started using GithubActions CI for additional testing
Log:
Fixed compilation for riscv32 target.
Mp11:
Added mp_intersperse, mp_split, mp_join
Multi-index Containers:
Maintenance work.
PFR:
A MurMur Hash based implementation of hash_combine() is now used to reduce \ 
collisions count and improve quality of boost::pfr::hash_value()
Visual Studio 2017 now supported in C++14 mode (thanks to Denis Mikhailov aka \ 
@denzor200)
Issues found by inspect tool were fixed
Fixed some warnings, including removal of extra semicolons in \ 
include/boost/pfr/detail/fields_count.hpp
Added a compile time assert for inherited types (thanks to Denis Mikhailov aka \ 
@denzor200)
Reflection of aggregates with non movable fields is now possible if guaranteed \ 
copy elision is on
Fixed spelling issues
Started using GithubActions CI for additional testing
PropertyTree:
This is a maintenance release.
Extend compiler coverage in CI.
Fix Boost compatibility for CMakeLists.txt.
System:
The conversion operator from error_category to std::error_category has been \ 
improved and no longer requires <map> or <mutex>.
The comparison operators of error_category are now inline friends instead of \ 
member functions (a side effect of the previous change.)
error_condition now defers calling generic_category() to avoid instantiating the \ 
object until it's actually needed.
error_condition::failed and error_condition::message have been undeprecated, and \ 
operator bool() now once again returns failed().
The system category now doesn't call generic_category(), to avoid instantiating \ 
the object.
The return value of default_error_condition changes in some cases into an \ 
error_condition from the generic category, instead of from the system category. \ 
This happens on POSIX when the input error_code is from the system category and \ 
does not correspond to any errc_t value.
The interoperability of error_code and std::error_code has been improved \ 
substantially. It is now possible to construct boost::system::error_code from \ 
std::error_code, and it's possible to pass boost::system::error_code to \ 
functions taking std::error_code&.
A stream insertion operator for error_condition has been added.
Uuid:
Added to_chars for writing uuid strings without allocating