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.