Latest Release (1.92.0)

Added a "scheduler" / "assume_continuation" configuration parameter, which allows posted handlers to be added to a fast thread-local queue.

Added "reactor" configuration parameters for tuning the io_uring backend: io_uring_ring_count, io_uring_ring_size, io_uring_submit_batch_size and io_uring_iowait.

Added the ability to configure ssl::stream<>'s internal buffer sizes.

Added a forward declarations header boost/asio/fwd.hpp to safely forward declare Asio class names when using the versioned namespace.

Added an example for using cancel_after with coroutines.

Added support for co_composed under BOOST_ASIO_NO_EXCEPTIONS.

Added a missing optimisation for concurrency_hint == 1 in io_context::poll_one().

Changed all exception classes to use inline implementations, to fix an undefined symbol error on some platforms when using separate compilation.

Changed constants and CPOs to use external linkage for C++17 and later.

Changed "slim" mutexes to use futexes on Linux.

Changed the reactor to use MSG_DONTWAIT, if supported, rather than setting the socket to be non-blocking.

Fixed two co_composed crashes on MSVC, one when using multiple completion signatures, and one due to insufficient alignment.

Fixed the return type on one cancel_after overload.

Fixed an integer truncation issue in basic_streambuf::commit/consume.

Fixed a buffer invalidation error triggered when SSL streams are moved, and clarified the buffer invalidation semantics.

Fixed a compilation error, seen on some compilers, that occurs when using post, dispatch or defer with a completion handler.

Fixed parallel_group handling of non-terminal cancellation requests.

Fixed some thread sanitizer warnings due to atomic thread fences, and added extra thread sanitizer instrumentation.

Fixed a signed/unsigned warning in basic_resolver_results, and suppressed some case fall-through warnings.

Fixed experimental::channel compilation with older versions of MSVC.

Fixed the multicast::enable_loopback socket option size on NetBSD and OpenBSD.

Fixed standard library coroutine detection when using clang-cl.

Improved cross-referencing within the documentation.

Consult the Revision History for further details.

Fix BOOST_VERIFY in the rare case of both BOOST_ENABLE_ASSERT_HANDLER and BOOST_ENABLE_ASSERT_DEBUG_HANDLER being defined.

websocket::stream accepts close code 1014 (bad gateway).

http::basic_parser ignores connection and framing fields in trailers.

http::parser drops framing and connection-control fields carried in trailers.

http::basic_parser rejects chunked transfer-encoding in HTTP/1.0 requests.

http::basic_parser rejects Content-Length with Transfer-Encoding regardless of field order.

http::basic_parser rejects requests with a Transfer-Encoding that does not end in chunked.

http::basic_parser validates quoted-strings in chunk extensions.

http::message::prepare_payload rejects 1xx responses with a body.

websocket::stream rejects 64-bit frame lengths with the high bit set.

File operations clear the error_code on success.

The server-flex-awaitable example dispatches cancellation to the task’s strand.

Removed dependency on Boost.Functional.

Added CUDA support allowing both to_chars and from_chars for integers to be used in CUDA kernels

Fixed support for Clang on PPC64LE as it keeps long double and __float128 as distinct types which was previously considered invalid via static_assert

Hashing a valueless std::variant instance no longer throws.

Added new boost::container::hub container designed by Joaquín M. López Muñoz.

Fixed bugs/issues:

Added unchecked_emplace_back and unchecked_push_back to boost::container::vector, boost::container::static_vector, and boost::container::small_vector.

Implemented C++23 P1518 change: modified allocator-extended constructors for all containers so that the deduction guides for containers are not overconstrained.

C++20 Module boost.conversion was implemented. Many thanks to Fedor Osetrov for the PR (PR#43)!

Added initial CUDA support allowing decimal32_t, decimal64_t, and decimal128_t to be used in CUDA kernels

Added decompose function which returns the significand, exponent, and sign without normalization (i.e. in their current cohort)

Fixed smart_library constructors from shared_library (PR#114). Many thanks to R. Savchenko for the PR!

C++20 Module boost.dll was implemented. Many thanks to Fedor Osetrov for the PRs (PR#110, PR#111, PR#112)!

Marked templated versions of initial_path as deprecated and removed from v4. Use the non-templated versions instead.

Use readdir instead of readdir_r on more POSIX platforms, specifically on Mac OS and other Apple operating systems, FreeBSD, OpenBSD, DragonFly BSD, NetBSD, QNX 6.0 and later, Solaris 10 and later and Illumos-based systems. Solaris users with gcc are recommended to define SunOS_5_x macros according to their target Solaris version (e.g. SunOS_5_11) when building Boost. (#349)

Support for platforms with non-thread-safe readdir is deprecated and will be removed in a future release. Although not required until POSIX.1-2024, on modern systems readdir is thread-safe when used with separate DIR objects in different threads and on some systems readdir_r is marked as deprecated. POSIX.1-2024 has been updated accordingly and also marked readdir_r as obsolescent, with a planned removal in a future version of the specification.

On POSIX platforms, handle EINTR error code returned from opendir, readdir and equivalents. Although not documented, this error code, reportedly, may be returned on Apple operating systems and some BSD systems.

Improvements (geometry):

Solved issues (geometry):

Added a Louvain community detection algorithm for modularity-based clustering (PR#453).

Removed the dependency on Boost.StaticAssert (PR#450).

Fixed bugs and correctness issues:

Modernized types and hygiene:

Documentation: updated the entire documentation and migrated to a new visual design (PR#469, PR#491, PR#509, PR#517, PR#519).

Added built-in support for std::optional

Added built-in support for std::variant, std::monostate

This release is the last to support C++14. Future releases will require C++17.

Starting with version 22, libc++ has changed some lookup algorithms of its associative containers in a way that breaks ICL’s assumptions and behavior. The library internals have been refactored to solve the problem and make ICL robust against future decisions of the C++ committee regarding non-heterogeneous lookup for associative containers (PR#54, LWG4752).

Fixed C++20-related problems with std::iter_value_t<element_iterator> and GCC 10-12’s handling of rewritten relational operators (PR#54).

Fixed a GCC 10-11 codegen bug (PR#54).

Fixed bugs:

Added is_*_iterator_v variable templates in C++14 and later, equivalent to the corresponding iterator traits.

The distance and advance algorithms are now constrained by requiring is_iterator to return true for the iterator arguments. (PR#96)

C++20 Module boost.lexical_cast was implemented. Many thanks to Fedor Osetrov for the PR (PR#96)!

This release is the last to support C++14. Future releases will require C++17.

Added new boost::lockfree::mpsc_weak_queue, a multi-producer, single-consumer queue. While push and pop are individually wait-free, the queue is not linearizable and a producer that stalls between exchanging the tail and linking its node can permanently break the queue, so it is not strictly lock-free.

Added new boost::lockfree::bounded_ticket_queue, a ringbuffer-based bounded MPMC queue. The queue is linearizable and wait-free when configured with a single producer and single consumer. In multi-producer or multi-consumer configurations, a stalled thread that has claimed a slot can block progress, so the queue is not strictly lock-free.

Added a degree of freedom finder to the Student’s T and Non-centeral F disributions

Fixed CUDA compilation where host functions were invalidly being marked as device during compilation

Increased testing coverage of distributions leading to several overflow fixes

Improved the performance of a number of algorithms (contributed by Jonathan Poelen)

mqtt_client::async_run now completes immediately with client::error::already_running when the client is already running (#54).

Fixed several missing length checks when decoding packets received from the broker. Malformed packets could previously cause out-of-bounds reads or excessive memory allocation. Many thanks to Team-Atlanta for reporting these issues.

New features (backmp11):

Bug fixes (backmp11):

Breaking changes (backmp11):

fix(back, back11): Infinite recursion with event deferral in orthogonal regions (regression from 1.78) (#184)

Fancy pointer support has been extended so that multi_index_container iterators now store references to the elements through the allocator’s pointer type. In particular, this means that iterators can now be placed in shared memory using Boost.Interprocess allocators.

Fixed a performance issue with hashed indices when rehashing at very large container sizes (PR#94). Contributed by Daniel Král.

Added data() member function to float128 to match the rest of the library

Fixed issue blocking compilation of constexpr expression templates with Clang

Added a way to configure which character set the server uses by default, to make tracking more intelligent. This can be used to avoid redundant SET NAMES statements. See pool_params::charset_strategy and connect_params::server_default_charset (PR#511).

Reduces `pool_params::ping_interval’s default from 1h to 10s. This improves the detection of broken connections (PR#512).

The read buffer has been optimized by reducing the frequency of data rotations when incomplete messages are received (PR#501). Contributed by