Known Issues

These are patches from library authors which were found too late to be fixed in the release. Be careful as they have not been through the normal testing process.

• Outcome status_code_domain assertion removal

  • Outcome patch
• Beast and coroutines

  • Beast patch

New Libraries

• Nowide: Standard library functions with UTF-8 API on Windows, from Artyom Beilis.
• StaticString: A dynamically resizable string of characters with compile-time fixed capacity and contiguous embedded storage, from Vinnie Falco and Krystian Stasiowski

Updated Libraries

• Align:

  • Update aligned_alloc to support older mingw32.
• Any:

  • Speedup compilation by not including <algorithm>.
  • Maintenance work, including CI hardening.
• Asio:

  • Fixed compatibility with C++20 concept syntax.
  • Marked the POSIX descriptor classes' move constructors as noexcept.
  • Added the ssl::host_name_verification class, which is a drop-in replacement for ssl::rfc2818_verification. The ssl::rfc2818_verification class has been marked as deprecated. As a consequence of this change, SSL support now depends on functions that were introduced in OpenSSL 1.0.2.
  • Added an ssl::context constructor to take ownership of a native handle.
  • Changed C++ language version detection with gcc to use __cplusplus macro.
  • Fixed a work counting issue in the asynchronous resolve operation for endpoints.
  • Fixed the strand<> converting constructors and assignment operators.
  • Ensured that resolvers are restarted correctly after a fork.
  • Fixed compatibility with the current NetBSD release.
  • Removed spurious handler requirement checks in some async_read overloads.
  • Changed the ssl::context class to propagate non-EOF errors from the add_certificate_authority function.
  • Fixed a Windows-specific thread_pool destructor hang that occurred when the pool had an associated I/O object.
  • Changed the select reactor to recreate the "self pipe trick" sockets on error. This addresses an issue on some versions of Windows, where these sockets are discconected after a system sleep.
  • Fixed a compile error in the buffered streams due to the lack of reference collapsing in C++98.
  • Changed the priority_scheduler example to demonstrate calls to shutdown() and destroy().
  • Removed some unnecessary null pointer checks.
  • Changed Windows platform detection to recognise TV titles as Windows apps.
  • Added some emscripten compatibility patches.
  • Fixed a compile error in the use_awaitable_t::as_default_on function.
  • Changed all uses of the boost.bind placeholders to use the boost::placeholders namespace.
  • Fixed a potential compile error in the async_compose implementation due to incorrect overload selection.
  • Suppressed some non-virtual destructor warnings.
  • Various documentation fixes and improvements.
• Assert:

  • Added source_location.
• Atomic:

  • Implemented C++20 atomic_ref. See docs and especially the caveats section.
  • Implemented atomic_flag::test operation, which was introduced in C++20.
  • atomic<T> should now take into account alignment requirements of T, which makes a difference if those requirements are higher than that of the internal storage of atomic.
  • Added static asserts enforcing the requirements on the value type T used with atomic and atomic_ref. This should prohibit invalid types from being used as atomics.
  • Improved internal lock pool implementation. The pool is larger, and lock selection accounts for atomic object alignment, which should reduce the potential of thread contention.
  • Fixed incorrect x86 code generated for bit_test_and_* operations on 8 and 16-bit arguments. Other architectures are not affected.
  • Fixed a possible unaligned memory access in compare_exchange_* operations, if alignment requirements of value_type are less than that of the internal storage of atomic.
  • boost/atomic/atomic.hpp no longer includes boost/atomic/atomic_flag.hpp and boost/atomic/fences.hpp and only defines the boost::atomic class template and related typedefs. Include the other headers explicitly or use boost/atomic.hpp to include all parts of Boost.Atomic.
  • The atomic<T>::storage() accessor and associated atomic<T>::storage_type type are deprecated. Instead, users are advised to use atomic<T>::value() and atomic<T>::value_type, respectively. Users can define BOOST_ATOMIC_SILENCE_STORAGE_DEPRECATION to disable deprecation warnings for the time of transition. The deprecated pieces will be removed in a future release.
  • Removed support for BOOST_ATOMIC_DETAIL_HIGHLIGHT_OP_AND_TEST. This macro was used as a helper for transition to the updated returned values of *_and_test operations in Boost.Atomic 1.67, which was released 2 years before 1.73.
• Beast:

  • This is a maintenance update.
  • Nested mutable_data_type in Beast dynamic buffers is deprecated.
  • We'd love to know how you or your company use Beast, consider adding an entry to the Companies and Individuals Using Beast list.
  • See the full Release Notes for a complete list of changes.
• Context:

  • #133: IBM Z: Fix fcontext routines
  • #132: mips64/n64: .align 3
  • #131: Use OSPLAT MIPS32/MIPS64 to set different ABI
  • #129: Fix non-PIC in RISC-V assembly
• Conversion:

  • Added boost::polymorphic_downcast for references (thanks to Julien Delacroix for the patch).
  • Significant docs update.
• date_time:

  • #123: Support constexpr in c++14 and above
  • #134: Make date_time all inline. Users no longer need to link the library for any functions. Library remains for build compatibility.
  • #132: Deprecate support for legacy io and USE_DATE_TIME_PRE_1_33_FACET_IO macro
  • Misc documentation updates and bugfixes.
• DLL:

  • Fixes and tests for demangling in boost::dll::smart_library (thanks to Ramil Gauss for #35).
  • Make UB sanitizers happy with boost::dll::load_mode::type #30.
  • Ceased dependence on MPL improving compile times (thanks to Nikita Kniazev for #34).
  • Clang and ICC on Windows fixes and CI support for those platforms (thanks to Nikita Kniazev #33).
  • Maintenance work, including CI hardening and tests improving.
• Dynamic Bitset:

  • Fixed a portability issue in the definition of the maximum block limit.
• Flyweight:

  • Maintenance work.
• Geometry:

  • Improvements

    • PR#650 Missing input combinations in intersection() and introduction of tupled-output.
    • PR#671 Added d3::point_xyz geometry model (thanks to Digvijay Janartha).
  • Solved issues

    • #657 Incorrect definition of EPSG:3785.
  • Bugfixes

    • PR#639 R-tree exception-safety improvement.
    • PR#668 Andoyer inverse formula fixed for close points.
    • PR#687 Fixed dangling reference in distance algorithm.
  • Deprecation

    • #590 Support for C++03 has been deprecated and Geometry will require C++14 from Boost 1.75 onwards.
• GIL:

  • Added

    • Added move constructor and move assignment operator to image class (PR#457).
    • New member function size() in any_image_view class (PR#456).
  • Changed

    • Replace Boost.Test with Boost.LightweightTest as the only test framework used in GIL (PR#459) and (PR#464). This also restructured the test/extension/io/ sub-tree and targets in related Jamfile-s.
    • Removed remaining uses of Boost.MPL (PR#459).
    • Renamed all macros using BOOST_GIL_ prefix (PR#411).
    • Renamed all CMake configuration options using BOOST_GIL_ prefix (PR#419).
  • Changed

    • Removed extension/dynamic_image/reduce.hpp as unused and possibly unfinished (PR#466). An implementation attempt of techniques described in the paper Efficient Run-Time Dispatching in Generic Programming with Minimal Code Bloat by Lubomir Bourdev, Jaakko Jarvi.
    • Removed direct dependency on Boost.MPL, Boost.System and Boost.Test.
    • Started removing public macros for compile-time configuration of I/O extension tests, i.e. BOOST_GIL_IO_TEST_ALLOW_READING_IMAGES and BOOST_GIL_IO_TEST_ALLOW_WRITING_IMAGES. Instead, if a test target is built, it builds all its test cases unconditionally.
  • Fixed

    • Avoid longjmp interaction during destruction of I/O extension objects (PR#433).
    • Fixed missing alignment default value in constructor of image class (PR#429).
    • Fixed segmentation fault when reading corrupted PNG file (PR#414).
    • Fixed illegal initialization of return values in the old IOv1 interface of I/O extension (PR#409).
  • Acknowledgements

    • Samuel Debionne, Thiago Henrique Hüpner, Pranam Lashkari, Mateusz Loskot, Debabrata Mandal, Olzhas Zhumabek
• Histogram:

  • New features

    • Added crop command to reduce algorithm
    • slice command in reduce now works on category axis
    • Added count accumulator, can be used to add arbitrary metadata to each cell
    • sum algorithm gained a new argument to optionally sum only over inner bins
  • Several fixes for bugs in corner cases
  • Enhanced documentation

    • How to use Boost.Histogram as a backend in an external API
    • More on how to use Boost.Histogram with custom accumulators and Boost.Accumulators
    • More on how to use reduce
    • Updated benchmarks
  • See the full changelog here
• icl:

  • PR#23: Remove references to date_time compiled library.
  • PR#17: Fix forward decl lower and upper less equal.
  • Misc bugfixes.
• IO:

  • Made all the IOS state saver classes non-copyable. (Glen Fernandes)
  • Correctly handle error upon first read from the input stream when reading a quoted string. (Glen Fernandes)
  • Implemented ostream_joiner for delimiter based joining. (Glen Fernandes)
  • Relocated ostream_string from the Utility library to the IO library as ostream_put.
  • Correctly handle stream width and fill in quoted output. (Glen Fernandes)
  • Optimize quoted output to write directly to the stream buffer. (Glen Fernandes)
  • Glen Fernandes became the maintainer of the IO library.
• LexicalCast:

  • Maintenance work, including CI hardening and better workarounds for broken standard libraries (thanks to Nikita Kniazev #31, #32).
• Log:

  • New Features:

    • Default sink used in trivial logging, when no sinks are registered in the logging core, now automatically flushes output after each log record. (#103)
    • core::flush now performs a flush on the default sink used for trivial logging, when no sinks are registered.
  • Bug fixes:

    • Added a workaround for some syslog API implementations (e.g. glibc), which do not save the application identification string in openlog call. Such implementations could access already freed memory on each syslog call, resulting in undefined behavior. (#97)
    • Fixed that log file rotation on a specific day of month (e.g. rotation_at_time_point(boost::gregorian::greg_day(1))) could be silently ignored and not happen. (#98)
    • Fixed that text_file_backend::rotate_file could throw if there were no log records written yet and target file name pattern was set.
    • Ported various components of the library to std::allocator_traits to improve compatibility with C++20 allocators.
    • Fixed compilation errors when building in MSYS2 Cygwin environment. (#102)
  • See changelog for more details.
• Math:

  • IMPORTANT: C++03 support is now deprecated and will be removed from March 2021.
  • Added Cubic Hermite Interpolation.
  • Added Modified Akima Interpolation.
  • Added PCHIP Interpolation.
  • Added Quintic Hermite Interpolation.
  • Added entropy to numerous distributions.
  • Allow trivial quadrature case where the two end points are equal, and in addition allow bounds to be interchanged.
  • Fix exp_sinh quadrature to work with complex types over a non-native range.
  • Fix miscellaneous compiler warnings in factorial.hpp.
  • Use std::chrono rather than boost::chrono in timed pFq calculations.
  • Remove much of the old boost::mpl dependencies to improve constexpr support.
• Mp11:

  • Added mp_unique_if (contributed by Kris Jusiak)
  • Added mp_flatten
  • Added mp_rotate_left, mp_rotate_right (contributed by Duncan Barber)
  • Added mp_compose
  • Added mp_power_set
  • Added mp_partial_sum
  • Added mp_iterate
• Multi-index Containers:

  • multi_index_container is now AllocatorAware.
  • Swapping of internal KeyFromValue, Compare, Hash and Pred objects now selects the appropriate swap function between std::swap and ADL candidates, in accordance with standard specifications in [swappable.requirements] (issue #29).
  • Provided some internal copy constructors and assignment operators whose default implicit definition is deprecated in C++11 onwards ([depr.impldec]), which was warned about on some compilers.
  • Maintenance work.
• Multiprecision:

  • IMPORTANT: Mark C++03 support as deprecated and due for removal in 2021.
  • Big update to cpp_int adds faster Karatsuba and Coomba multiplication routines.
  • Fix conversion of gmp_rational to long double and __float128, fixes #178.
  • Fix up libtommath support to function with the latest libtom releases.
  • Fix up some incompatibilities with the latest Intel C++ compiler.
  • Fix up constexpr arithmetic support for latest MSVC release.
• Outcome:

  • Enhancements:

    • Performance of Outcome-based code compiled by clang has been greatly improved. The previous implementation of Outcome's status bitfield confused clang's optimiser, which caused low quality codegen. Unlike most codegen issues, this was noticeably in empirical benchmarks of real world code, as was shown by P1886 Error speed benchmarking.
    • The safe part of the better_optimisation Outcome v2.2.0 future branch was merged to Outcome v2.1.3 which includes a new status bitfield implementation. This appears to not confuse clang's optimiser, and clang 9 produces code which routinely beats GCC 9's code for various canned use cases.
    • Installability is now CI tested per commit. Due to installability of standalone Outcome (e.g. make install) breaking itself rather more frequently than is ideal, installability is now tested on CI per commit.
  • Bug fixes:

    • #214 Newer Concepts implementing compilers were unhappy with the early check for destructibility of T and E, so removed template constraints, falling back to static assert which runs later in the type instantiation sequence.
    • #220 A false positive undefined behaviour sanitiser failure in some use cases of Experimental Outcome was worked around to avoid the failure message.
• PolyCollection:

  • Suppressed a potential redundant move warning in boost::poly_collection::for_each.
  • Fixed a bug by which elements were copied rather than moved in allocator-extended move construction and move assigment between collections with non-propagating, unequal allocators.
  • Allocator-extended move construction no longer decays to allocator-extended copy construction for the legacy version of libstdc++-v3 shipped with GCC 4.8 (which can also be used by Clang).
• Stacktrace:

  • Added documentation on distribution of PDBs #55, #47 (thanks to emptyVoid and Roger Orr for information and to zlojvavan for testing).
  • Fixed msvc-9 build
  • Maintenance work, including test fixes #86, fixing typos #84, CI improvements and hardening, inspect tool fixes.
• Test:

  • Boost.test v3.13 see the Changes log for more details.
  • New feature: It is now possible to combine tolerance indication, user message and collection comparison modifier in a single BOOST_TEST expression. See change logs for more details.
  • Bug fixes and pull requests:

    • GitHub Issues: #173, #179, #220, #221, #235 #237, #241, #245, #246, #251, #253 #254, #263
    • Trac tickets: #11107
    • GitHub Pull Requests: PR#41, PR#114, PR#187, PR#239, PR#247 PR#252, PR#259, PR#265
• ThrowException:

  • Added an overload of throw_exception that takes a boost::source_location object.
  • NOTE: Projects using BOOST_THROW_EXCEPTION with exceptions disabled will need to add a definition of this new overload.
• TTI:

  • Added introspection of function templates for more recent C++ compilers versions from gcc and vc++. as well as all versions of clang. Older versions of vc++ before 14.0 and gcc prior to 4.8 may fail.
  • Added specific introspection for elements of struct/class, enum, and union types, which can be used for more fine-grained introspection than the general 'type' introspection.
• TypeIndex:

  • Maintenance work, including CI integration with inspect tool.
• Utility:

  • The ostream_string facility has moved from the Utility library to the IO library as ostream_put.
• Variant:

  • Removed unused includes (thanks to Nikita Kniazev #74).
  • Fixed zero-as-null-pointer-constat warnings (thanks to Bart Siwek #77).
  • Maintenance work, including typo fixes.
• Variant2:

  • Added support for std::hash, boost::hash.
  • variant<T...> is now trivial when all types in T... are trivial. This improves performance by enabling it to be passed to, and returned from, functions in registers.
• WinAPI:

  • Headers in boost/detail/winapi are deprecated and will be removed in a future release.
  • Boost.WinAPI headers no longer include winerror.h. Include boost/winapi/error_codes.hpp to get Windows error codes. (#81)

Updated Tools

• Build:

  • Includes release 4.2.0 of B2.
  • WARNING: Since version 4.0.0 B2 requires a capable C++11 compiler to bootstrap. This is only needed to build B2 itself not to build Boost for your use.

Compilers Tested

Boost's primary test compilers are:

• Linux:

  • Clang: 3.0, 4.0.1, 6.0.1
  • Clang, C++0x: 3.0
  • Clang, C++11: 3.0, 3.1, 3.2, 3.3, 3.4, 4.0.1, 6.0.1, 7.0.0, 8.0.0
  • Clang, C++14: 3.5.0, 3.6.0, 3.7.1, 3.8.0, 3.9.1, 4.0.0, 4.0.1, 5.0.2, 6.0.1, 7.0.0, 8.0.0
  • Clang, C++17: 5.0.2, 6.0.1, 7.0.0, 8.0.0
  • GCC: 4.4.7, 4.5.3, 4.6.3, 5.4.0, 8.0.1
  • GCC, C++0x: 4.4.7
  • GCC, C++11: 4.7.3, 4.8.5, 4.9.4, 5.4.0, 6.4.0, 7.1.0, 8.0.1
  • GCC, C++14: 5.4.0, 5.5.0, 6.4.0, 7.1.0, 7.3.0, 8.0.1
  • GCC, C++17: 7.3.0, 8.0.1
  • Intel, C++14: 18.0
• OS X:

  • Apple Clang: 9.0.0, 9.1.0, 10.0.0
  • Apple Clang, C++11: 9.0.0, 9.1.0, 10.0.0
  • Apple Clang, C++14: 9.0.0, 9.1.0, 10.0.0
  • Apple Clang, C++17: 9.1.0, 10.0.0
  • Apple Clang, C++1z: 9.0.0
  • Apple Clang, C++2a: 10.0.0
• Windows:

  • GCC: 3.4.5, 4.1.2, 4.2.4, 4.3.3, 4.4.0, 4.5.4
  • GCC, C++0x: 4.6.4
  • GCC, C++11: 4.7.3, 4.8.1, 4.9.3
  • GCC, C++14: 5.1.0, 5.2.0, 5.3.0, 6.1.0, 6.2.0, 6.3.0, 6.4.0
  • GCC, C++17: 7.1.0, 7.2.0, 7.3.0
  • Visual C++: 7.1, 8.0, 9.0, 10.0, 11.0, 12.0, 14.0, 14.1
• FreeBSD:

  • Clang: 4.0.0
  • Clang, C++11: 4.0.0
  • Clang, C++14: 4.0.0
  • Clang, C++1z: 4.0.0

Boost's additional test compilers include:

• Linux:

  • Clang: 3.0, 3.8.1, 3.9.1, 4.0.1, 5.0.2, 6.0.1
  • Clang, C++0x: 3.0
  • Clang, C++11: 3.0, 3.1, 3.2, 3.3, 3.4, 4.0.1, 6.0.1, 7.0.0, 8.0.0
  • Clang, C++14: 3.5.0, 3.6.0, 3.7.1, 3.8.0, 3.9.1, 4.0.0, 4.0.1, 5.0.2, 6.0.1, 7.0.0, 8.0.0
  • Clang, C++17: 5.0.2, 6.0.1, 7.0.0, 8.0.0
  • GCC: 4.4.7, 4.5.3, 4.6.3, 4.9.4, 5.4.0, 5.5.0, 8.0.1
  • GCC, C++0x: 4.4.7
  • GCC, C++11: 4.7.3, 4.8.5, 4.9.4, 5.4.0, 6.4.0, 7.1.0, 8.0.1
  • GCC, C++14: 5.4.0, 5.5.0, 6.3.0, 6.4.0, 7.1.0, 7.3.0, 8.0.1, 8.1.0
  • GCC, C++17: 7.3.0, 8.0.1
  • Intel, C++14: 18.0
• OS X:

  • Apple Clang: 9.0.0, 9.1.0, 10.0.0
  • Apple Clang, C++11: 9.0.0, 9.1.0, 10.0.0
  • Apple Clang, C++14: 9.0.0, 9.1.0, 10.0.0
  • Apple Clang, C++17: 9.1.0, 10.0.0
  • Apple Clang, C++1z: 9.0.0
  • Apple Clang, C++2a: 10.0.0
• Windows:

  • GCC: 3.4.5, 4.1.2, 4.2.4, 4.3.3, 4.4.0, 4.5.4
  • GCC, C++0x: 4.6.4
  • GCC, C++11: 4.7.3, 4.8.1, 4.9.3
  • GCC, C++14: 5.1.0, 5.2.0, 5.3.0, 6.1.0, 6.2.0, 6.3.0, 6.4.0
  • GCC, C++17: 7.1.0, 7.2.0, 7.3.0
  • Visual C++: 7.1, 8.0, 9.0, 10.0, 11.0, 12.0, 14.0, 14.1
• FreeBSD:

  • Clang: 4.0.0
  • Clang, C++11: 4.0.0
  • Clang, C++14: 4.0.0
  • Clang, C++1z: 4.0.0

Acknowledgements

Marshall Clow, Michael Caisse and Glen Fernandes managed this release.