Boost News

1. 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. (PR#65)
   • 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 (PR#42).
   • 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 PR#28!
   • 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(). (#301)
     • 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. (#300)
     • 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. (#179)
     • 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

       • PR#1247 Use if constexpr macro instead of condition macro
       • PR#1242 Pass strategy to sort by side
       • PR#1234 Add cmake files for clang/mac/darwin/arm64
     • Solved issues

       • #1231, #1244 Fix invalid set operations for CCW polygons
       • #1259 Fix compilation error with CUDA NVCC compiler
       • #1250 Fix buffer of linestring returning incorrect inner polygon
       • #1230 Fix union operation perturbing a point and returning wrong result
       • #1229 Fix union producing self intersections
       • PR#1248 Fix buffer issue by setting turns in closed clusters as non traversable
       • PR#1246 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 (thanks to 13steinj for the report #64!);
       • 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 #30.
     • 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 #45.
   • 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 PR#216
     • Throw an exception when a faulty IConv library is detected (e.g. on some MacOS versions) instead of looping indefinitely PR#218
     • Reduce resolution of date_time to seconds as milliseconds where not easily available causing confusion #221
   • Math:

     • Added a new collection of optimization algorithms:

       • Differential Evolution PR#1062
       • JSO PR#1065
       • Random Search PR#1071
       • CMA-ES PR#1074
     • 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 PR#1060
     • Improve cstdfloat iostream PR#1066
     • 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> PR#575
     • Fix cpp_bin_float for small bit counts PR#577
     • Fix -Wpessimizing-move PR#580
     • Add covecov runs
     • Reduce truncation in cpp_dec_float multiplication PR#585
     • Fix complex_adaptor to match precision requirements PR#597
     • Fix for breaking changes in tommath PR#603
     • Fix for types that can be converted to number participting in arithmetic operator overloads #608
   • 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 PR#152!
     • Removed unused implementation details. Thanks to Denis Mikhailov for the PR PR#154.
     • Allow throwing exceptions from boost::pfr::structure_to_tuple. Thanks to Denis Mikhailov for the bug report #155.
     • Field reflection trick is now described in the docs. Thanks to all the discussion participans in #150!
   • Random:

     • Added splitmix64 PRNG PR#89
   • 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. Thanks to ycyclop for reporting the issue #111, to Thiago A. Correa for providing more information, to Andrei Karpovskii for providing a possible fix.
     • Fixed library build with non hidden visibility. Thanks to Jan Bouwer for the report and information on how to fix it.
     • Added a separate section on async signal safety to the docs. Many thanks to tworonix for highlighting the problem in #131 and to itrofimow for information on the problem.
   • 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 PR#406
     • Supress MSVC C4702 from __builtin_unreachable() on intentionally unreachable code
     • Fix boost::function streaming error PR#411
   • 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 (PR#234).
     • Fixed bug in the const version of unordered_multimap::find(k, hash, eq) (PR#238).
   • Variant:

     • Removed more of the pre-C++11 macro and workarounds.
   • Wave: Fixed bugs:

     • #200: Emitted pragmas lack terminating newline
     • #202: YYMARKER not updated when fill called on BOOST_WAVE_BSIZE boundary

   Updated Tools

   • Build:

     • Includes release of B2 version 5.1.0.

   Compilers Tested

   Boost's primary test compilers are:

   • Linux:

     • Clang, C++03: 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++11: 3.4, 11.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++14: 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++17: 6.0.1, 7.0.0, 8.0.0, 9.0.0, 10.0.0, 11.0.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++20: 11.0.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • GCC, C++03: 4.6.3, 11, 12
     • GCC, C++11: 4.7.3, 4.8.5, 11, 12
     • GCC, C++14: 5.4.0, 6.4.0, 7.3.0, 8.0.1, 9.1.0, 11, 12
     • GCC, C++17: 7.3.0, 8.0.1, 9.1.0, 11, 12
     • GCC, C++20: 8.0.1, 9.1.0, 10, 11, 12
   • OS X:

     • Apple Clang, C++03: 11.0.3
     • Apple Clang, C++11: 11.0.3
     • Apple Clang, C++14: 11.0.3
     • Apple Clang, C++17: 11.0.3
     • Apple Clang, C++20: 11.0.3
   • Windows:

     • Visual C++: 10.0, 11.0, 12.0, 14.0, 14.1, 14.2, 14.3

   Acknowledgements

   Marshall Clow and Glen Fernandes managed this release.

2. Version 1.84.0

   Updated default target Windows version

   Boost.WinAPI, a library that is used internally by other Boost libraries for defining Windows SDK components, has been updated to target Windows 10 API by default, where possible. This means that Boost libraries will target Windows 10 by default and may not run on older Windows versions. This includes the pre-built binaries that are distributed by Boost.

   The affected libraries include:

   • Boost.Atomic
   • Boost.Beast
   • Boost.Chrono
   • Boost.DateTime
   • Boost.DLL
   • Boost.Filesystem
   • Boost.Interprocess
   • Boost.Log
   • Boost.Pool
   • Boost.Process
   • Boost.System
   • Boost.Stacktrace
   • Boost.Thread
   • Boost.UUID

   as well as libraries that depend on the above.

   Users are able to change the default by defining BOOST_USE_WINAPI_VERSION or _WIN32_WINNT when building and using Boost to the required version number. For example, to build Boost targeting Windows 7 one could use a command line like this:

       b2 variant=release define=BOOST_USE_WINAPI_VERSION=0x0601 stage
   

   Note, however, that individual libraries may have their own requirements on the minimum supported Windows version.

   The list of Windows API version numbers can be seen on this page.

   New Libraries

   • Cobalt: Basic algorithms and types for C++20 coroutines, from Klemens Morgenstern.
   • Redis: Redis async client library built on top of Boost.Asio, from Marcelo Zimbres Silva.

   Updated Libraries

   • Any:

     • C++03 is no longer supported PR#26.
     • Fixed reference documentation generation. Now it is not overwritten by Boost.PFR reference. Thanks to Peter Dimov for the debugging.
   • Asio:

     • Changed to require C++11 as the minimum language standard. C++03 is no longer supported.
     • Removed deprecated functionality from the boost::asio::execution namespace.
     • Removed deprecated invocation and allocation hooks.
     • Added try_send_via_dispatch and try_send_n_via_dispatch functions to channels.
     • Added compatibility between Asio's placeholders and std::bind.
     • Improved C++11 support for channels that have multiple completion signatures.
     • Fixed compatibility between channel asynchronous operations and any_completion_handler.
     • Fixed compatibility between any_completion_handler and compilation using BOOST_ASIO_USE_TS_EXECUTOR_AS_DEFAULT.
     • Added missing equality operators for comparing mixed executor property types belonging to the same category.
     • Fixed an issue where spawn-based stackful coroutines would terminate the program when used with asynchronous operations that have a completion signature starting with std::exception_ptr.
     • Fixed a crash that may occur when attempting to access a default-constructed any_completion_handler object's associators.
     • Fixed ssl::stream<> class's async_handshake operation so that it works with a defaulted completion token.
     • Updated all examples to use C++11 as the minimum language standard.
   • Atomic:

     • C++03 is no longer supported, the minimum required language version is C++11.
     • Added support for x87 extended double with reduced precision, which is used on FreeBSD and OpenBSD. (#14)
     • Support for Windows versions older than Windows 10 is deprecated and will be removed in Boost 1.87.
   • Beast:

     • Support for immediate_executor.
     • Remove deprecated allocation and invocation hooks.
     • Use the explicit type std::size_t when completing transfer_op.
     • Replaced BOOST_ASIO_INITFN_RESULT_TYPE with BOOST_ASIO_INITFN_AUTO_RES.
     • server-flex-awaitable example resets parser.
     • Corrected the websocket::stream::async_ping/pong handler requirement.
     • Update documentation for websocket::stream::async_write_some.
   • Chrono:

     • C++03 is no longer supported.
   • ContainerHash:

     • C++03 is no longer supported.
   • Conversion:

     • C++03 is no longer supported PR#27.
   • Core:

     • boost::swap utility function has been renamed to boost::core::invoke_swap to avoid forming a potential infinite recursion when the arguments are not swappable. The new function is defined in boost/core/invoke_swap.hpp and is functionally equivalent to boost::swap. The old boost::swap name is preserved for backward compatibility but deprecated and will be removed in a future release. Its noexcept specification has been removed to avoid compile errors caused by compile-time recursion. BOOST_ALLOW_DEPRECATED_SYMBOLS or BOOST_ALLOW_DEPRECATED can be defined to suppress deprecation warnings for the transition period. (#148)
     • Headers boost/swap.hpp, boost/utility/swap.hpp and boost/core/swap.hpp are deprecated and will be removed. Please, switch to boost/core/invoke_swap.hpp. BOOST_ALLOW_DEPRECATED_HEADERS or BOOST_ALLOW_DEPRECATED can be defined to suppress deprecation warnings.
   • CRC:

     • C++03 support is deprecated and will be removed in release 1.86.
   • DLL:

     • C++03 is no longer supported PR#66.
   • Endian:

     • C++03 is no longer supported.
   • Filesystem:

     • As was announced in Boost 1.82.0, C++03 is no longer supported. A C++11 or later compiler is required.
     • Fixed that some directory_entry observers taking error_code& ec argument did not clear the error code on successful return. (#291)
     • On Windows, improved robustness of date and time conversion and added support for dates before January 1, 1970. (#293)
     • Removed support for Windows CE that was deprecated since Boost.Filesystem 1.79.0.
     • Removed boost/filesystem/string_file.hpp header. The header was deprecated since Boost.Filesystem 1.79.0.
     • Deprecated: Support for Windows versions older than Windows 10 is deprecated and will be removed in Boost 1.87.
   • Geometry:

     • Solved issues

       • #1138 Fix difference of two polygons
       • #1183 Fix for union_ incomplete result polygon
       • #1184 Fix for intersection
       • #1186 Fix for union_ improper inner ring assignment
       • Various fixes of errors and warnings
   • Heap:

     • C++03 support is deprecated and will be removed in release 1.86. New requirement will be C++14.
   • JSON:

     • Implement parsing directly into user types.
     • Add conversion categories for optionals and variants.
     • Relax iterator requirements for constructors from iterator pairs.
     • Fix reading beyond input buffer.
     • Fix inconsistent choice of init list constructor.
   • LEAF:

     • class result<T> marked nodiscard.
     • Added member typedef result<T>::value_type.
     • verbose_diagnostic_info defers conversion to string until an error handling scope is reached.
     • Improved support for embedded development.
     • Improved Visual Studio 2015 compatibility (thanks godmaycrying).
     • Minor bug fixes an improvements.
     • Dropped support for GCC 4.8 and 4.9.
   • LexicalCast:

     • C++03 is no longer supported PR#62.
     • Fixed -Wdeprecated-copy-with-dtor warnings with clang. Thanks to Romain Geissler for the PR PR#59!
     • Dropped dependency on Boost.Range PR#63.
   • Locale:

     • to_title for the WinAPI backend returns the string unchanged instead of an empty string
     • Improved support for char8_t and std::u8string
     • Fix off-by-one error when using negative times PR#198
     • Fix escape-handling of curly braces in format strings #194
     • Fix some build errors and warnings, notably one on MSVC, see #189
   • Lockfree:

     • C++03 support is deprecated and will be removed in release 1.86. New requirement will be C++14.
   • Log:

     • C++03 is no longer supported. A C++11 or later compiler is required.
     • When built with C++11 compilers that are conforming enough for Boost.Regex v5 to be used, Boost.Log no longer links with Boost.Regex prebuilt library, since Boost.Regex v5 is header-only.
     • Support for Windows versions older than Windows 10 is deprecated and will be removed in Boost 1.87.
   • Math:

     • Improve ccmath error detection.
     • Remove use of deprecated std::numeric_limits<>::has_denorm, see 1028.
     • Correct non-convergence bug in non-central-t distribution, see 1035.
     • Adjust Bessel function approximation to [sub 1]F[sub 1] to avoid taking tgamma at a negative integer, see 1034.
     • Avoid spurious overflow and divide by zero in ibeta, see 1006.
     • Improve accuracy when using Sterling's approximation to tgamma, completes work started in 1007.
     • Fix inverse_discrete_quantile for large initial guesses, see 1007.
     • Improve Newton root finding, see 1000.
     • Fix median_absolute_deviation for non-zero centre, see 997.
     • Fix up cstdfloat.hpp for gcc-14.
     • Update to work for the new types declared in <stdfloat>.
     • Change hypergeometric_distribution to use 64 rather than 32 bit integers to avoid unnecessary overflow and restrictions on use.
   • Multi-index Containers:

     • Fixed a serialization-related compile-time bug in old compilers without ADL support (issue #70).
   • Multiprecision:

     • Change boost::array to std::array in the tests, fixes 567.
     • Correct cpp_int::eval_convert_to to be noexcept, fixes 553.
     • Make sure that changing the global precision, also changes the current thread precision.
     • Fix rational_adaptor construction bug, fixes 540.
   • MySQL:

     • Added connection::reset_connection and connection::async_reset_connection. These functions clean session state (including prepared statements, variables, locks and more) without closing and re-opening the connection.
     • Added error codes introduced in MySQL server v8.1.0.
     • Added fuzz testing for the deserialization functions.
   • PFR:

     • Big new feature: field names reflection. Added new constexpr boost::pfr::get_name<N, T>() function that returns a std::string_view with a name of field at index N of an aggregate T. Requires C++20. BOOST_PFR_CORE_NAME_ENABLED is defined to 1 if the functionality is available. Many thanks to Denis Mikhailov, Bela Schaum and X-Ryl669 for the PR PR#129 and implementation ideas.
     • for_each_field() is now constexpr for C++17. Many thanks to Alexander Karatarakis for the PR PR#134.
   • Predef:

     • Version 1.15.0
     • Add detection of Microsoft STL (from Henrik Gaßmann).
   • Random:

     • C++03 is no longer supported.
     • Fixed overflows in tests using Boost.Multiprecision
   • Ratio:

     • C++03 is no longer supported.
     • Support for BOOST_RATIO_EXTENSIONS has been removed. Ratio is now implemented in terms of the standard <ratio> header.
   • Stacktrace:

     • C++03 is no longer supported. Thanks to Alex for the PR PR#139
     • Fixed addr2line for pie binaries. Thanks to ja2142 for the PR PR#138!
     • Fixed build with MinGW-w64 12+. Thanks to yhsb2k for the PR PR#140!
     • Added missing include. Thanks to Francesco Ballarin for the PR PR#143!
   • System:

     • Added support for result<U&, E>.
     • Added operator| for result.
     • Added operator& for result.
     • Added operator&= for result.
   • Test:

     • C++03 is no longer supported.
     • Fixed useage of PRIxPTR for glibc 2.2 - 2.17 PR#392
     • Fixed MSVC warning C5263: calling 'std::move' on a temporary object prevents copy elision PR#390
   • Thread:

     • C++03 is no longer supported.
   • TypeIndex:

     • C++03 is no longer supported.
     • BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS((A)(B)(C)(D)) changed syntax to BOOST_TYPE_INDEX_REGISTER_RUNTIME_CLASS(A, B, C, D).
     • Dropped Boost.PP dependency.
   • TypeOf:

     • C++03 is no longer supported.
   • Unordered:

     • Major update.
     • Added boost::concurrent_flat_set.
     • Added [c]visit_while operations to concurrent containers, with serial and parallel variants.
     • Added efficient move construction of boost::unordered_flat_(map|set) from boost::concurrent_flat_(map|set) and vice versa.
     • Added bulk visitation to concurrent containers for increased lookup performance.
     • Added debug-mode mechanisms for detecting illegal reentrancies into a concurrent container from user code.
     • Added Boost.Serialization support to all containers and their (non-local) iterator types.
     • Added support for fancy pointers to open-addressing and concurrent containers. This enables scenarios like the use of Boost.Interprocess allocators to construct containers in shared memory.
     • Fixed bug in member of pointer operator for local iterators of closed-addressing containers (PR#221, credit goes to GitHub user vslashg for finding and fixing this issue).
     • Starting with this release, boost::unordered_[multi]set and boost::unordered_[multi]map only work with C++11 onwards.
   • variant:

     • C++03 is no longer supported PR#107.
     • Dropped Boost.Move and Boost.Bind dependencies.
   • Wave: Fixed bugs:

     • #188: Segmentation fault when "#pragma\n" is encountered

   Compilers Tested

   Boost's primary test compilers are:

   • Linux:

     • Clang, C++03: 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++11: 3.4, 11.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++14: 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++17: 6.0.1, 7.0.0, 8.0.0, 9.0.0, 10.0.0, 11.0.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++20: 11.0.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • GCC, C++03: 4.6.3, 11, 12
     • GCC, C++11: 4.7.3, 4.8.5, 11, 12
     • GCC, C++14: 5.4.0, 6.4.0, 7.3.0, 8.0.1, 9.1.0, 11, 12
     • GCC, C++17: 7.3.0, 8.0.1, 9.1.0, 11, 12
     • GCC, C++20: 8.0.1, 9.1.0, 10, 11, 12
   • OS X:

     • Apple Clang, C++03: 11.0.3
     • Apple Clang, C++11: 11.0.3
     • Apple Clang, C++14: 11.0.3
     • Apple Clang, C++17: 11.0.3
     • Apple Clang, C++20: 11.0.3
   • Windows:

     • Visual C++: 10.0, 11.0, 12.0, 14.0, 14.1, 14.2, 14.3

   Acknowledgements

   Marshall Clow and Glen Fernandes managed this release.

3. Version 1.83.0

   Known Issues

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

   • JSON

     • Compilation on Windows ARM platforms may fail for missing intrinsics, see #926 and #927. Patch.
   • Unordered

     • Fix erroneous copy assigment operator that would destroy non-existent elements, see #205. Patch.

   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. (#62)
   • 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 for the bugreport #58.
   • 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. (#288)
     • File streams defined in boost/filesystem/fstream.hpp are now movable, if the standard library file streams are. (#280)
     • 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. (#285)
     • Fixed potential overload resolution ambiguity in users' code, where path constructors from iterators could interfere with function overloads taking a std::initializer_list argument. (#287)
     • On Windows, added more workarounds for errors returned by various filesystems when creating a directory iterator. (#284, #286)
     • On Windows, relaxed access rights needed for querying file times. (#290)
   • 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 (issue #12).
   • Geometry:

     • Improvements

       • PR#1140 Drop dependencies and replace boost with std in several places
       • PR#1154 Add missing headers so that all headers compile independently complying with Boost policy
       • PR#1157 Check const Ring concept in calculate_point_order
     • Solved issues

       • #1100 Fix for union
       • #1139 Fix for different geometry types
       • #1158 Fix for convex hull
       • #1161 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. (PR#79)
   • 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. (#209)
   • 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 (issue #68).
     • 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. (#757)
     • url_view/string_view constructor requires non-url_view_base. (#756)
     • IP-literal can be IPv6addrz. (#711)
   • 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. (PR#138)
   • Variant2:

     • Added uses_double_storage().

   Updated Tools

   • Build:

     • Includes release of B2 version 4.10.1.

   Compilers Tested

   Boost's primary test compilers are:

   • Linux:

     • Clang, C++03: 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++11: 3.4, 11.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++14: 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++17: 6.0.1, 7.0.0, 8.0.0, 9.0.0, 10.0.0, 11.0.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++20: 11.0.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • GCC, C++03: 4.6.3, 11, 12
     • GCC, C++11: 4.7.3, 4.8.5, 11, 12
     • GCC, C++14: 5.4.0, 6.4.0, 7.3.0, 8.0.1, 9.1.0, 11, 12
     • GCC, C++17: 7.3.0, 8.0.1, 9.1.0, 11, 12
     • GCC, C++20: 8.0.1, 9.1.0, 10, 11, 12
   • OS X:

     • Apple Clang, C++03: 11.0.3
     • Apple Clang, C++11: 11.0.3
     • Apple Clang, C++14: 11.0.3
     • Apple Clang, C++17: 11.0.3
     • Apple Clang, C++20: 11.0.3
   • Windows:

     • Visual C++: 10.0, 11.0, 12.0, 14.0, 14.1, 14.2, 14.3

   Acknowledgements

   Marshall Clow and Glen Fernandes managed this release.

4. Version 1.82.0

   Known Issues

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

   • Filesystem

     • Compilation on OpenBSD may fail because of broken support for -Wl,--no-undefined compiler flag for shared libraries on this platform, see #283. Patch.
     • On Windows, creating directory iterators over directories in SMBv1 shares may fail with ERROR_INVALID_LEVEL error code, see #284. Patch.

   Notice of Dropping C++03 Support

   The following libraries will be dropping C++03 support in release 1.84, two releases from now:

   • Align
   • Any
   • Asio
   • Atomic
   • Bind
   • Chrono
   • ContainerHash
   • Conversion
   • DLL
   • Endian
   • Filesystem
   • Function
   • Functional
   • Io
   • LexicalCast
   • Log
   • Random
   • Ratio
   • SmartPtr
   • System
   • Stacktrace
   • Thread
   • Timer
   • TypeIndex
   • Typeof
   • Unordered
   • Variant

   This release (1.82) and the next (1.83) will be the last releases offering C++03 support for the above libraries and most of their dependencies.

   The new baseline requirement for the above libraries, and for most of Boost, will be C++11. Since old compiler versions often implement C++11 only partially, due to missing support or bugs, what compilers are considered to meet the C++11 requirement may vary by library.

   However, a general rule is that if a compiler does not recognize a C++11 keyword or syntax at all (e.g. use of noexcept, use of constexpr, or defining a =deleted function results in an immediate compile error), or if a compiler does not provide a required C++11 header at all (e.g. trying to include <atomic> or <chrono> fails), or the compiler provides a C++11 feature or a header that is completely unusable, this compiler is not considered a C++11 compiler.

   This rules out, for instance, Microsoft Visual C++ before 14.0, or GCC before 4.8.

   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. Thanks to Michael Ford for the PR PR#25.
   • 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, thanks to Travers Biddle for the PR PR#57.
   • Filesystem:

     • Fixed compilation errors that could have been caused by path conversion constructors being too permissive on the accepted arguments. (#273)
     • v4: path::remove_filename now presesrves the trailing directory separator. (#271)
     • 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. (#279)
     • 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. (#282)
   • Geometry:

     • Major improvements

       • PR#1045 Support geographic buffer for (multi)linestrings and (multi)polygons
     • Improvements

       • PR#1114 Comparable distance: Add support for dynamic geometries
       • PR#1046 Support covered_by() for box, geometry combinations
     • Solved issues

       • #705 WKT: allow tabs and new lines
       • #1109, #1108 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 PR#144
     • 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 PR#148
     • Treat en_US_POSIX as an alias for the C locale PR#148
     • Improve error for missing segmentation support (i.e. without ICU) PR#149
     • 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 PR#170
   • PFR:

     • Implemented the boost::pfr::is_implicitly_reflectable and the machinery for specializing aggregates as reflectable or not, thanks to Denis Mikhailov for the PR PR#111.
     • Implemented boost::pfr::get by type of an element in the aggregate.
     • Implemented the BOOST_PFR_ENABLED macro to detect library support for reflection, thanks to Denis Mikhailov for the PR PR#86.
     • Fixed missing terminating character, thanks to Denis Mikhailov for the PR PR#114.
     • Fixed the boost/pfr/config.hpp compilation on older compilers, thanks to Denis Mikhailov for the PR PR#118.
     • Workaround for broken C++17 stuctured binding in old compilers, thanks to Denis Mikhailov for the PR PR#119.
     • Avoid -Wzero-as-null-pointer-constant warnings, thanks to Markus F.X.J. Oberhumer for the PR PR#117.
     • Fixed multiple typos, thanks to Denis Mikhailov for the fixes.
     • Added missing #pragma once, thanks to caozhanhao for the PR PR#121.
     • 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 PR#132.
     • 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. Thanks to Michael Ford for the PR PR#105.

   Updated Tools

   • Build:

     • Includes release of B2 version 4.9.4.

   Compilers Tested

   Boost's primary test compilers are:

   • Linux:

     • Clang, C++03: 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++11: 3.4, 11.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++14: 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++17: 6.0.1, 7.0.0, 8.0.0, 9.0.0, 10.0.0, 11.0.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++20: 11.0.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • GCC, C++03: 4.6.3, 11, 12
     • GCC, C++11: 4.7.3, 4.8.5, 11, 12
     • GCC, C++14: 5.4.0, 6.4.0, 7.3.0, 8.0.1, 9.1.0, 11, 12
     • GCC, C++17: 7.3.0, 8.0.1, 9.1.0, 11, 12
     • GCC, C++20: 8.0.1, 9.1.0, 10, 11, 12
   • OS X:

     • Apple Clang, C++03: 11.0.3
     • Apple Clang, C++11: 11.0.3
     • Apple Clang, C++14: 11.0.3
     • Apple Clang, C++17: 11.0.3
     • Apple Clang, C++20: 11.0.3
   • Windows:

     • Visual C++: 10.0, 11.0, 12.0, 14.0, 14.1, 14.2, 14.3

   Acknowledgements

   Marshall Clow and Glen Fernandes managed this release.

5. 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

       • #1048 Index: Fix dangling references when Indexable is returned by value by IndexableGetter
       • #1076 Union: in rare cases it might miss one polygon
       • #1081 Union: due to precision it might miss interior rings
     • Bugfixes

       • #1063 Intersection: fix a bug in intersection of simple spherical polygons
       • #1064 Formulas: fix a consistency issue in geodesic direct formulas
       • #1088 Point: Fix regression for custom point types
       • 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-Michaël 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.

   Compilers Tested

   Boost's primary test compilers are:

   • Linux:

     • Clang: 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++11: 3.4, 11.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++14: 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++17: 6.0.1, 7.0.0, 8.0.0, 9.0.0, 10.0.0, 11.0.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • Clang, C++20: 11.0.0, 12.0.0, 13.0.0, 14.0.0, 15.0.0
     • GCC: 4.6.3, 11, 12
     • GCC, C++11: 4.7.3, 4.8.5, 11, 12
     • GCC, C++14: 5.4.0, 6.4.0, 7.3.0, 8.0.1, 9.1.0, 11, 12
     • GCC, C++17: 7.3.0, 8.0.1, 9.1.0, 11, 12
     • GCC, C++20: 8.0.1, 9.1.0, 10, 11, 12
   • OS X:

     • Apple Clang: 11.0.3
     • Apple Clang, C++11: 11.0.3
     • Apple Clang, C++14: 11.0.3
     • Apple Clang, C++17: 11.0.3
     • Apple Clang, C++20: 11.0.3
   • Windows:

     • Visual C++: 10.0, 11.0, 12.0, 14.0, 14.1, 14.2, 14.3

   Acknowledgements

   Marshall Clow and Glen Fernandes managed this release.