New Libraries

• Parser: Framework for building parsers, from Zach Laine.

Updated Libraries

• Asio:

  • Added support for using byte spans and sequences of byte spans as buffer sequences. This means that they can be passed directly to I/O operations such as async_read.
  • Added support for generic dispositions, which are types that can be used to test whether an asynchronous operation completed without error. This includes error_code and exception_ptr, but can be extended to user types via specialisation of the disposition_traits class template. The standard types std::error_code and std::exception_ptr are recognised as dispositions.
  • Added disposition support to the boost::asio::use_future completion token, boost::asio::awaitable<>-based coroutines, boost::asio::spawn(), and boost::asio::experimental::cancellation_condition.
  • Added the execution_context::service_maker abstract base class. A service_maker is an object that is passed to an execution context's constructor, and allows services to be added at context construction time.
  • Added boost::asio::config, which provides access to configuration parameters that are associated with an execution context. The class is intended for use by asio internals, or by libraries or user-provided abstractions that build on top of asio, and will typically be used to fine tune behaviour, such as enabling or disabling certain optimisations. A concrete configuration source, such as boost::asio::config_from_env, boost::asio::config_from_concurrency_hint and boost::asio::config_from_string, may be passed to the io_context or thread_pool constructor.
  • Added an initial set of configuration parameters recognised by Asio's io_context and thread_pool implementations.
  • Removed some previously deprecated facilities.
  • Deprecated basic_io_object and deadline_timer.
  • Added rvalue-qualified operator() overloads to associating binders.
  • Added support for modular build structure.
  • Fixed spawn() of functions that return move-only types.
  • Fixed co_composed to not require concepts support.
  • Fixed the epoll reactor to not try to re-register regular file descriptors after fork.
  • Fixed a leak in ssl::detail::engine move assignment.
  • Fixed compile error when BOOST_ASIO_DISABLE_SMALL_BLOCK_RECYCLING is defined.
  • Fixed compile error when using Clang 19.
  • Changed thread_pool::join() to ensure that it stops threads that are subsequently added to the pool using thread_pool::attach().
  • Fixed the offsets passed to io_uring_prep_write_fixed and io_uring_prep_read_fixed, when they are used for stream-oriented operations.
  • Consult the Revision History for further details.
• Atomic:

  • Fixed initialization of atomic wait state list on memory reallocation. (#72)
• Beast:

  • API Changes

    • Added error_code overload for basic_fields::insert().
    • Added overload for websocket::stream::get_status to query permessage-deflate status.
  • Fixes

    • Fixed use-after-move in calls to net::dispatch within http::basic_stream, which caused bad_executor exceptions on timeouts.
    • Removed mutating operations in initiating functions.
    • Fixed cancellation handling in teardown_tcp_op.
    • Set state_ in basic_parser before calling on_finish_impl.
    • Removed static specifier from clamp functions.
    • Addressed -Wattributes warnings in tests.
    • Addressed unreachable code warning in tests.
  • Improvements

    • Added forward declaration headers for types in beast::http namespace
    • Enabled http::parser to use basic_fields::insert() with error_code overload
    • Applied header_limit_ in http::basic_parser to trailer headers
    • Improved http::basic_parser to return http::error::header_limit earlier
    • Added support for modular boost build structure
  • Acknowledgements

    • Jackarain, Saleh Hatefinya, René Ferdinand Rivera Morell
• Charconv:

  • Fixed support for PPC64LE architecture using __ibm128 as long double format
  • Fixed intrinsic usage with Windows ARM64 platform
  • Fixed formatting of fixed with specified precision using std::float128_t or __float128
• Cobalt:

  • Removed requirement for get_executor to return a const ref
  • Added experimental/composition.
• Compat:

  • Added to_array.hpp (contributed by Ruben Perez Hidalgo.)
• Container:

  • Added stored_size option to static_vector and small_vector.
  • Fixed bugs/issues:

    • GitHub #261: "End iterators are not dereferencable".
    • GitHub #288: "Compile error when using flat_map::extract_sequence with small_vector".
• Filesystem:

  • As was announced in 1.84.0, Windows versions prior to 10 are no longer supported.
  • On Windows, canonical is now based on the GetFinalPathNameByHandleW WinAPI function. As a side effect, drive letters are converted to upper case, which makes the resulting paths more interoperable. (#325)
  • v4: canonical no longer produces a trailing directory separator in the resulting path, if the input path has one.
  • If a path constructor or member function is called with an argument of a user-defined type that is convertible to path and one or more Source types, the conversion to path is now chosen by default. This may resolve argument conversion ambiguities in some cases, but may also result in a less optimal conversion path. If a different conversion path is desired, users are recommended to use explicit type casts. (#326)
  • Added a workaround for dirfd being a macro on FreeBSD 9 and older. (#328)
• Flyweight:

  • Added concurrent_factory, a factory based on a concurrent container from Boost.Unordered that provides excellent performance in multithreaded scenarios.
  • Marked as noexcept those boost::flyweight operations previously documented as not throwing (issue #15).
• Geometry:

  • Improvements

    • Use using instead of typedef in part of the code
    • Modernize meta function with alias in part of the code
    • Add support for modular build structure
    • Complete CMake coverage (added github actions cmake tests)
    • Improve documentation workflow
    • Update Qt end WxWidgets examples
    • Add enumerate to prepare for 17 and 23
  • Breaking changes

    • Remove deprecated rescaling code
  • Solved issues

    • #1309 Fix some missing qbk includes
    • #1226 #1326 Fix extra round on ring
    • #1293 #1294 #1295 Fix traversal through non clustered rings
    • #893 #1299 Fix blocking rings for non union conditions
    • #1342 Fix discarding a start turn for combination with touch
    • #1288 #1345 Fixes in handling (imperfect) touch
    • #1279 Fix covered_by incorrect results
    • Various fixes of errors and warnings
• Iterator:

  • function_output_iterator is now compliant with std::output_iterator concept. (#85)
• Interprocess:

  • Decreased number of Boost dependencies from 11 (in total) to 7.
  • Deprecated <boost/interprocess/containers/*.hpp> headers. They were the original source of Boost.Container in 2011, but no longer maintained. As a long transition, Boost.Interprocess has maintained those headers for compatibility. They will be removed in a future Boost release.
  • Some workarounds for Cygwin were added. Regression tests now work on Cygwin64.
  • ABI breaking: segment_manager nows uses a new implementation that supports overaligned types and fixes some existing bugs. You can obtain the pre-Boost 1.87 ABI #defining BOOST_INTERPROCESS_SEGMENT_MANAGER_ABI to 1 before including Boost.Interprocess headers.
  • Fixed bugs:

    • GitHub #152 ("Handle EINTR in shared_memory_object").
    • GitHub #173 ("Managed shared memory segment value not aligned").
    • GitHub #192 ("managed_windows_shared_memory crash on destruction").
    • GitHub #199 ("missing/misused m_is_wide in char_wchar_holder assignment operators").
    • GitHub #210 ("Bug in boost::interprocess::ipcdetail::sync_handles::obtain_mutex").
    • GitHub #215 ("Alignment problem with boost/interprocess/segment_manager on SPARC 32Bit").
    • GitHub #217 ("managed_map_file find_or_construct does not return Cache aligned memory").
    • GitHub #230 ("interprocess::ipcdetail::intermodule_singleton not working on MinGW").
    • GitHub #236 (" Floating point inaccuracies in get_current_process_creation_time lead to intermodule_singleton` failures").
• JSON:

  • Direct serialization.
  • Add GDB pretty printers for Boost.JSON types.
  • Conversion into structs ignores unknown keys.
  • Exception wrapping behaviour for value_to is simplified.
  • Deprecated initilaizer list behavior was removed.
  • Deprecated type aliases were removed.
  • Use correct 64bit full multiplication for MinGW on ARM64.
  • Fix parse_into handling of tuple of the wrong size.
  • Check for input size larger than allowed size of sequence.
  • Fix value_ref segfaulting on GCC 14.
• LexicalCast:

  • Dropped dependency on Boost.Integer, leading to better compile times.
• Log:

  • Replaced Boost.Thread synchronization primitives with equivalents from the C++ standard library. This may improve multithreaded performance, but also has user-facing consequences:

    • Boost.Thread thread interruption is no longer supported. Boost.Log no longer has special treatment for the thread_interrupted exception that is used by Boost.Thread to implement thread interruption. This exception will be handled like any other exception. In particular, user-specified exception handlers may now be invoked with the thread_interrupted pending exception.
    • For timed waiting operations, timeouts are now using std::chrono time units. This means that the ordering_window named parameter that is supported by the bounded_ordering_queue and unbounded_ordering_queue classes now expects an std::chrono::duration value instead of boost::posix_time::time_duration from Boost.DateTime.
    • In case of errors indicated by thread synchronization primitives, std::system_error exception is thrown instead of Boost.Thread exception types.
  • Added support for C++ standard library lock types to strictest_lock.
• Math:

  • Major update.
  • Many special functions, and distribuitions now support CUDA (NVCC and NVRTC) and SYCL
  • Added mapairy, holtsmark, and saspoint5 distibutions, see 1163
  • Added landau distibution, see 1159
  • Fixed unexpected exception in beta quantile, see 1169
• Move:

  • Fixed bugs:

    • Git Issue #56: "Forward declarations of std types cause compilation errors on some platforms".
• Mp11:

  • Added mp_lambda (contributed by Joaquin M Lopez Munoz)
• Multiprecision:

  • Make float128 trivially copyable
  • Make __float128 a floating point type even in non-GNU modes
• MySQL:

  • Breaking changes to experimental APIs:

    • The thread-safety feature in connection_pool has been redesigned to overcome some design flaws found by user experience. The boolean option thread_safe has been added to pool_params (set to false by default). When set, some pool functions change behavior so they can be safely used concurrently. This works by internally creating a strand, dispatching to it when required, and re-wiring cancellation signals. When pool_params::thread_safe is false, the usual Asio executor semantics apply, with no overhead.
    • pool_executor_params has been removed, replaced by pool_params::connection_executor and pool_params::thread_safe.
    • The built-in timeout functionality in connection_pool::async_get_connection has been completely removed. This function now supports per-operation cancellation, so the same functionality can be achieved by using asio::cancel_after.
    • Destroying a connection_pool now cancels outstanding async operations, as other Asio I/O objects do. This prevents resource leaks: an outstanding async_run operation extends the pool's lifetime until the operation completes, which could cause the pool object to never get destroyed.
    • When an async_get_connection operation is cancelled before a connection is available, the operation now consistently fails with client_errc::pool_not_running, client_errc::no_connection_available or client_errc::pool_cancelled, depending on the pool state (previously, it would fail with either client_errc::timeout or the last error code encountered by the internal async_connect operations performed by the pool). This information is now included in the output diagnostics object.
    • client_errc::timeout and client_errc::cancelled have been removed.
    • Calling async_get_connection on a pool that is not running no longer fails immediately, but waits for async_run to be called.
    • sequence now returns an owning type. This makes it safe use with with_params in deferred async operations. format_sequence_view has been renamed to format_sequence.
    • sequence has been moved to a separate header, boost/mysql/sequence.hpp.
  • any_connection, client-side SQL formatting (including format_sql and with_params) and connection_pool have been promoted to stable APIs.
  • any_connection is now recommended for new code, instead of connection and its aliases tcp_connection, tcp_ssl_connection and unix_connection.
  • Added with_params, a new ExecutionRequest encapsulating a query template string and parameters to expand the query. When executed, it expands the query using client-side SQL formatting and sends it to the server for execution. This is the new recommended way to run simple queries with parameters.
  • Added with_diagnostics, an adapter completion token that transforms exceptions thrown by async functions to include diagnostics objects, matching how sync throwing functions work.
  • with_diagnostics(asio::deferred) is now the default completion token for all operations in any_connection and connection_pool. This causes expressions like co_await conn.async_connect(params) to behave identically to conn.connect(params). Note that connection and its type aliases haven't been updated to match this behavior.
  • Async functions in connection_pool now support per-operation cancellation.
  • All async operations now support asio::cancel_after, asio::cancel_at and similar completion tokens that require a bound executor to initiations passed to asio::async_initiate.
  • connection and any_connection now dispatch immediate completions through the token's immediate executor.
  • Fixed an issue that caused a crash when trying to use an any_connection that hasn't been previously connected.
  • Removed an incorrect noexcept specifier from a potentially throwing constructor in field.
  • Fixed an issue that could cause the write buffer size to exceed the configured buffer size limit.
  • Heavily updated the documentation and examples to be more relevant and reflect the new recommended best practices.
• Optional:

  • Breaking change. Dropped support for C++03. C++11 is now the required minimum; at least some C++11 features.
  • Dropped dependency on Boost.Utility.
  • Dropped dependency on Boost.Predef.
  • Dropped dependency on Boost.StaticAssert.
  • Dropped dependency on Boost.Move.
  • A bit faster implementation of some relational operations.
  • Warning. In the future releases we intend to introduce the range interface into optional, so that std::ranges::range<optional<T>> will be true. This may affect the overload resolution in programs that make decisions based on predicates such as std::ranges::range.
  • Tags in_place_init and in_place_init_if become inline constexpr and therewith leave smaller footprint in the executable. This addresses issue #103.
• PFR:

  • boost::pfr::for_each_field_with_name function was added. Many thanks to Lena for the PR#171.
  • Significant compilation time improvement for structures with big size and small fields count. Many thanks to Zachary Wassall for the PR#120.
  • Fixed pragma directives.
  • Initial support for C++20 Modules. See the docs for more info.
  • Fix unused variable warnings in core_name14_disabled.hpp. Thanks to Anarthal (Rubén Pérez) for the PR#183 and PR#187.
  • Default limit for fields count in aggregate in C++17 was raised from 100 to 200.
  • Fixed warning about GCC not being aware of the -Wundefined-var-template.
  • Multiple minor improvement for compilation time.
• Process:

  • (v2) Implemented cancellation of async_wait on windows.
  • (v2) Added FORCE_DISABLE_CLOSE_RANGE
  • (v2) ext: Multiple ext fixes for BSD & Solaris.
  • (v2) unavailable ext functions now compile and give an operation_not_supported error (includes IOS)
  • (v2) multiple link fixes
  • (v2) removed filesystem from the linked library - which filsystem library is used only affects header files now
  • (v1) Added deprecation notice for 1.88.
• SmartPtr:

  • C++03 is no longer supported, a C++11 compiler is required. This includes GCC 4.8 or later, and MSVC 14.0 or later.
  • The functionality enabled by the macros BOOST_SP_ENABLE_DEBUG_HOOKS, BOOST_SP_USE_STD_ALLOCATOR, BOOST_SP_USE_QUICK_ALLOCATOR, BOOST_AC_USE_SPINLOCK, BOOST_AC_USE_PTHREADS, BOOST_SP_USE_SPINLOCK, and BOOST_SP_USE_PTHREADS has been deprecated and support for it will be removed in a future release.
• Stacktrace:

  • Boost::stacktrace_from_exception CMake target was added. Many thanks to int mian for the PR#189.
  • Don't export boost_stacktrace_impl_return_nullptr for static build on MSVC. Many thanks to huangqinjin for the PR#186.
  • Fixed autolinking with ole32.lib and Dbgeng.lib while using clang under Windows OS.
  • Fixed missing namespace in docs. Thanks to Mats Taraldsvik for the PR#181.
  • Fixed missing include for std::exception. Thanks to Julien Schueller for the PR#178.
  • Fixed type conversions errors reported by GCC. Thanks to agent_J for the PR#175.
  • Fixed setting B2 from_exception feature from CLI. Thanks to Dmitry Arkhipov for the PR#194.
• STLInterfaces:

  • Correct misdocumented requirements for sequence container swap; the expected return type is void, not bool. (#71)
  • Add [[no_unique_address]] to the data members of the adaptors in view_adaptor.hpp. (#65)
  • Enable deducing this for recent versions of Clang and MSVC that support it, but do not advertise that support via __cpp_explicit_this_parameter. (PR#68)
• Test:

  • Fixed support for clang tidy with dummy conditions PR#348
  • Fixed dynamic linking with clang PR#431
• Unordered:

  • Major update.
  • Added concurrent, node-based containers boost::concurrent_node_map and boost::concurrent_node_set.
  • Added insert_and_visit(x, f1, f2) and similar operations to concurrent containers, which allow for visitation of an element right after insertion (by contrast, insert_or_visit(x, f) only visits the element if insertion did not take place).
  • Made visitation exclusive-locked within certain boost::concurrent_flat_set operations to allow for safe mutable modification of elements (PR#265).
  • In Visual Studio Natvis, supported any container with an allocator that uses fancy pointers. This applies to any fancy pointer type, as long as the proper Natvis customization point "Intrinsic" functions are written for the fancy pointer type.
  • Added GDB pretty-printers for all containers and iterators. For a container with an allocator that uses fancy pointers, these only work if the proper pretty-printer is written for the fancy pointer type itself.
  • Fixed std::initializer_list assignment issues for open-addressing containers (PR#277).
  • Allowed non-copyable callables to be passed to the std::initializer_list overloads of insert_{and|or}_[c]visit for concurrent containers, by internally passing a std::reference_wrapper of the callable to the iterator-pair overloads.
• URL:

  • feat: set_params supports encoding_opts. (#856)
  • refactor: no deprecated variant2 alias from API. (#857)
  • refactor: query_rule consistent interpretation. (#864)
• UUID:

  • Restored the ability to construct a constexpr uuid that was inadvertently lost in 1.86.
• Wave:

  • Fixed bugs:

    • GitHub #220: "Seg fault under C++20 and empty stringify parameter". Thanks Lu HongYi
    • GitHub #222: "No line directive if first line of included file is blank". Thanks Nick Nobles
  • Build improvements including modular build support, thanks René Rivera

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, Glen Fernandes and Ion Gaztañaga managed this release.