////
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Official repository: https://github.com/boostorg/website-v2-docs
////

== Version 1.90.0

// Date of release
Month Day, Year Hour::Minute GMT

boost_at:/doc/libs/1_90_0/[Documentation]

// Formatting reference: https://docs.asciidoctor.org/asciidoc/latest/syntax-quick-reference/
// Boost-specific macros: https://github.com/cppalliance/asciidoctor-boost?tab=readme-ov-file#macros
// Please keep the list of libraries sorted in lexicographical order.

== New Libraries

// Example:
// 
// * boost_phrase:library[Accumulators,/libs/accumulators]:
// ** Framework for incremental calculation, and collection of statistical
// accumulators, from Eric Niebler.

* boost_phrase:library[OpenMethod,/libs/openmethod]:
** Open-(multi-)methods in C++17 and above, from Jean-Louis Leroy.

== Updated Libraries

// Example:
//  
// * boost_phrase:library[Interprocess,/libs/interprocess/]:
// ** Added anonymous shared memory for UNIX systems.
// ** Conform to `std::pointer_traits` requirements (boost_gh:pr[interprocess,32]).
// ** Fixed `named_condition_any` fails to notify (boost_gh:issue[interprocess,62]).

* boost_phrase:library[Beast,/libs/beast/]:
** `http::parser` rejects non-standard trailer fields by default.
** `http::basic_parser` uses a dedicated callback for trailer fields.
** `http::field` constants are updated.
** Fixed allocator move/copy assignment in `flat_buffer` and `multi_buffer`.
** Fixed websocket permessage-deflate error on partial message consumption.
** `http::buffer_body` ignores empty chunks.
** Added `http::basic_fields::contains` member function.
** Removed dependency on Boost.Preprocessor and Boost.StaticAssert.

* boost_phrase:library[Bloom,/libs/bloom/]:
** Added bulk-mode insertion and lookup for increased performance.
** Made lookup implementation branchless for `block`, `fast_multiblock32`
and `fast_multiblock64`, which results in some performance gains,
particularly for mixed successful/unsuccessful queries.

* boost_phrase:library[Compat,/libs/compat/]:
** Added `to_underlying.hpp` (contributed by Braden Ganetsky.)
** Extracted `nontype_t` to its own public header `nontype.hpp` and added `nontype`.

* boost_phrase:library[Container,/libs/container/]:
** Reimplemented `deque`. The original implementation was based on
   the SGI's original data structure (similar to libstdc++). Main changes:
*** `sizeof(deque)` was 10 words, now is 4 words. Probably the lightest implementation around.
*** `sizeof(deque::iterator)` was 4 words, now is is 2 words (similar to libc++ and MSVC).)
*** Several internal algorithms were reimplemented to speed up the segmented nature of deque.
*** Defaults were slightly changed, 64 bit platforms now use 1024 byte blocks by default instead of classic SGI 512 byte blocks.
*** The new implementation eases further deque-like variations and optimizations in the future.

** Fixed bugs/issues:
*** https://github.com/boostorg/container/issues/248[GitHub #248: "flat_map slow insertion introduced in boost-1.80.0"].
*** https://github.com/boostorg/container/issues/254[GitHub #254: "C++20 std::erase_if"].
*** https://github.com/boostorg/container/issues/293/[GitHub #293: "UBSAN reports unaligned access error"].
*** https://github.com/boostorg/container/pull/294[GitHub #294: "CMake: Add option to use header-only Boost::container"].
*** https://github.com/boostorg/container/issues/300[GitHub #300: "Warnings when building with Clang 20"].
*** https://github.com/boostorg/container/issues/304[GitHub #304: "Usage of boost::container::small_vector with custom allocator"].
*** https://github.com/boostorg/container/pull/305[GitHub #305: "Warnings with -Wstrict-prototypes"].
*** https://github.com/boostorg/container/pull/307[GitHub #307: "Fix all instances of MSVC warning C4146 (unsigned negation)"].
*** https://github.com/boostorg/container/issues/309[GitHub #309: "Performance regression of boost::container::static_vector introduced in boost v1.86"].
*** https://github.com/boostorg/container/issues/306[GitHub #306: "new_allocator.hpp error: '__cpp_sized_deallocation' is not defined, evaluates to 0 [-Werror,-Wundef]"].
*** https://github.com/boostorg/container/issues/310[GitHub #310: "flat_map: Mention correct type in documentation of emplace and emplace_hint"].
*** https://github.com/boostorg/container/issues/312[GitHub #312: "flat_map std::allocator::is_always_equal is deprecated"].
*** https://github.com/boostorg/container/pull/317/[GitHub #317: "Partial revert of changes for Issue #209 - compiler warnings"].
*** https://github.com/boostorg/container/pull/321/[GitHub #321: "devector does not work with pmr allocators"].


* boost_phrase:library[Core,/libs/core/]:
** The implementation of `BOOST_TEST_THROWS` and `BOOST_TEST_NO_THROW` macros defined in
   `boost/core/lightweight_test.hpp` has been changed to avoid
   compiler warnings on some compilers, when the macros are used in `if`/`else` blocks. As
   a side effect of this change, the semicolon after the macro is now necessary. (boost_gh:pr[core,205])
** `boost::data` and `boost::size` are now aliases for `std::data` and `std::size`,
   respectively, when the latter are provided by compiler. This resolves potential ambiguities
   when both `boost::` and `std::` alternatives are found by the compiler, e.g. as a result
   of ADL. (boost_gh:pr[core,206])

* boost_phrase:library[DynamicBitset,/libs/dynamic_bitset/]:
** Added C++20 iterators.
** Allowed choosing the underlying container type.
** Added constexpr support when compiling as C++20 or later.
** Made push_back(), pop_back() and lowest_bit() more efficient.
** Made the constructor from basic_string explicit.
** Removed several dependencies.
** Added push_front(), pop_front(), find_first_off(), find_next_off() and constructors
   from C-style strings and basic_string_view (the latter in C++17 or later).
** Changed the stream inserter to set badbit if an exception is thrown during output.
** Made the stream extractor rethrow any exception coming from the underlying vector.
** Ported the documentation to MrDocs and Antora.

* boost_phrase:library[Filesystem,/libs/filesystem/]:
** Clear passed `error_code` argument on successful completion of the `permissions` operation.
   (boost_gh:pr[filesystem,338])

* boost_phrase:library[Flyweight,/libs/flyweight/]:
** Fixed compile errors in Clang 19 and later due to https://wg21.link/p0522r0[P0522R0] support.

* boost_phrase:library[Interprocess,/libs/interprocess/]:
** Minor documentation fixes.
**  Fixed bugs:
*** https://github.com/boostorg/interprocess/pull/245[GitHub #245: "Fix UBSan runtime error (load of 'boost::interprocess::mode_t')"].
*** https://github.com/boostorg/interprocess/pull/269[GitHub #269: "Minor documentation fixes and template parameter renames"].

* boost_phrase:library[JSON,/libs/json/]:
** Removed dependencies on Boost.Align and Boost.StaticAssert.
** Switched to a faster hashing algorithm.

* boost_phrase:library[Log,/libs/log/]:
** Fixed a missed optimization in `value_ref` visitation.

* boost_phrase:library[Mp11,/libs/mp11/]:
** Updated `mp_reverse_fold` to work on fixed size lists

* boost_phrase:library[MSM,/libs/msm/]:
** Refurbished and updated the documentation to use Antora.
** Added a new back-end `backmp11` offering heavily reduced compile times, a refactored API and a couple of new features.
   Requires {cpp}17, more details are available in the documentation.
** Fixed bug https://github.com/boostorg/msm/issues/87[GitHub #87: "boost::any stopped working as Kleene event in 1.86 in boost::msm"].

* boost_phrase:library[MySQL,/libs/mysql/]:
** Deprecated support for Clang versions older than 4.0. These compilers might still work,
   but they won't be actively tested in CI.
** Added tests to guarantee compatibility with MySQL 9.x.
** Added tests to guarantee compatibility with Clang versions up to 20,
   and GCC versions up to 15.

* boost_phrase:library[Parser,/libs/parser/]:
** Fixed ill-formedness when using move-only callables with closures
   (boost_gh:pr[parser,284])
** Fix wonky `const`-incompatibility in `GlobalState` parser template params
   (boost_gh:issue[parser,250]).
** Fix ill-formedness in some cases when using the permutation parser
   (boost_gh:issue[parser,268]).
** Fixed an error in sequence parsing that could cause some attributes to be
   overwritten by later parsers in a sequence (boost_gh:issue[parser,279]).
** Fix the handling of opt-parsers that could leave a `std::optional`
   attribute containing a value even though the parser that produced it
   failed (boost_gh:issue[parser,279] and boost_gh:issue[parser,285]).
** Multiple runtime optimizations (boost_gh:issue[parser,245],
   boost_gh:pr[parser,254], boost_gh:pr[parser,255], boost_gh:pr[parser,256]).
** A modest compile-time and code size optimization
   (boost_gh:issue[parser,250]).
** Make `transform` `constexpr` (boost_gh:pr[parser,275]).      
** Move-versus-forward warning mitigation (boost_gh:issue[parser,272]).
** Correct the documentation for the attribute type of the `if_` directive
   (boost_gh:issue[parser,278]).
** Correct many, many typos in the docs (boost_gh:pr[parser,271]).

* boost_phrase:library[Redis,/libs/redis/]:
** Important changes to *cancellation*:
*** Improved the per-operation support in `async_exec()`, and added
    support for `asio::cancel_after`. Requests can now
    be cancelled at any point, and cancellations don't interfere with other
    requests anyhow.
    Pull requests boost_gh:pr[redis,310] and boost_gh:issue[redis,226].
*** Deprecated the `cancel_on_connection_lost` and `cancel_if_not_connected`
    flags in `request::config`.
    To limit the time span that `async_exec`
    might take, use `asio::cancel_after`, instead.
    `cancel_on_connection_lost` default has been changed to `false`.
    Pull requests boost_gh:pr[redis,329] and boost_gh:pr[redis,334].
*** Deprecated calling `cancel` with `operation::resolve`, `connect`,
    `ssl_handshake`, `reconnection` and `health_check`.
    Users should employ `cancel(operation::run)`, instead.
    Pull request boost_gh:pr[redis,321].
*** Added support for per-operation cancellation in `async_run()`.
    Issue boost_gh:issue[redis,319].
** Added support for *custom setup requests* using `config::setup`.
   When setting these fields, users can
   replace the library-generated `HELLO` request by any other arbitrary request.
   Issue boost_gh:issue[redis,302] and pull request boost_gh:pr[redis,303]. +
** Deprecated `request::config::hello_with_priority`.
   If you need to execute a request before any other, use `config::setup`, instead.
   Pull request boost_gh:pr[redis,305].
** *Valkey* long-term support: we guarantee Valkey compatibility
   starting with this release.
   Issue boost_gh:issue[redis,296].
** Added a `request::append()` function, to concatenate request objects.
   Issue boost_gh:issue[redis,341].
** The health checker algorithm has been redesigned to avoid
   false positives under heavy loads. `PING` commands are now
   only issued when the connection is idle, instead of periodically.
   Issue boost_gh:issue[redis,104].
** Added `config::read_buffer_append_size`, which allows to control
   the expansion of the connection's read buffer.
   Pull request boost_gh:pr[redis,283].
** Added `usage::bytes_rotated`, which measures data copying when
   reading and parsing data from the server.
   Pull request boost_gh:pr[redis,311].
** Bug fixes:
*** Fixed a bug causing an exception to be thrown when parsing
    a response that contains an intermediate error into a `generic_response`.
    Issue boost_gh:issue[redis,287].
*** Fixed a number of race conditions in the `cancel()` function
    of `connection` and `basic_connection` that could cause
    cancellations to be ignored.
    Issue boost_gh:issue[redis,318].
*** Users with an empty password but a non-default username are
    now correctly authenticated. Issue boost_gh:issue[redis,298].
*** Fixed a problem that could cause an error during `HELLO`
    to make subsequent `HELLO` attempts during reconnection to fail.
    Issue boost_gh:issue[redis,290].
*** Errors during `HELLO` are now correctly logged.
    Issue boost_gh:issue[redis,297].

* boost_phrase:library[SmartPtr,/libs/smart_ptr/]:
** The functionality enabled by the deprecated macros
   `BOOST_SP_ENABLE_DEBUG_HOOKS`, `BOOST_SP_USE_STD_ALLOCATOR`,
   and `BOOST_SP_USE_QUICK_ALLOCATOR` has been removed.
** The header `<boost/smart_ptr/detail/quick_allocator.hpp>` has
   been marked deprecated and will be removed in a future release.
** Configurations that define `BOOST_NO_CXX11_HDR_ATOMIC` are no
   longer supported; a conforming {cpp}11 `<atomic>` is now required.
** Consequently, Clang 3.5 and 3.6 are no longer supported.
** The deprecated macros `BOOST_AC_USE_SPINLOCK`, `BOOST_AC_USE_PTHREADS`,
   `BOOST_SP_USE_SPINLOCK`, and `BOOST_SP_USE_PTHREADS` are no longer
   functional.
** Platform-specific implementations of `atomic_count`, `sp_counted_base`
   and `spinlock` are no longer used and have been removed.
** Configurations that define `BOOST_NO_CXX11_HDR_MUTEX` are no
   longer supported; a conforming {cpp}11 `<mutex>` is now required.
** Some unused headers in `boost/smart_ptr/detail/` have been removed.

* boost_phrase:library[STLInterfaces,/libs/stl_interfaces/]:
** Fixed ill-formedness with GCC 14 (boost_gh:pr[stl_interfaces,80]).
** Fixed ill-formedness when using move-only callables with closures.

* boost_phrase:library[Uuid,/libs/uuid/]:
** `string_generator` is now `constexpr` on {cpp}14 and higher.
** Added header `boost/uuid/constants.hpp`.
** Renamed `boost/uuid/uuid_generators.hpp` to `boost/uuid/generators.hpp`. The old name is retained for compatibility.

* boost_phrase:library[Variant2,/libs/variant2/]:
** More functions have been marked as `constexpr`, including `~variant`.
   This didn't matter before {cpp}20, but does now.

== Compilers Tested

// Edit this section as appropriate

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

// Edit this section as appropriate

Marshall Clow, Glen Fernandes and Ion Gaztañaga managed this release.