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.