Release notes for work in progress boost

Version 1.80.0

Wed, 13 Jul 2022 21:36:22 +0000

New Libraries

No new libraries.

Updated Libraries

Atomic:
- Improved portability of endianness checks on ARM, AArch32 and AArch64 targets. (#59)
- Fixed compilation with MSVC 14.0 (Visual Studio 2015) in C++17 mode. (#61)
Beast:
- Fix CVE-2018-25032 in zlib streams
- Add http::message_generator: a type-erased buffers generator for http::message
- Improve interoperability with std::string_view by using boost::core::string_view (API change)
- Use span from Boost.Core (API change)
- Use static_string from Boost.StaticString (API change)
- See the full Release Notes for a complete list of changes.
Filesystem:
- On Windows, added a fallback implementation for querying file attributes in case if the file cannot be opened with ERROR_ACCESS_DENIED error. This may allow status and symlink_status to succeed for system files and directories that are not reparse points or symlinks. (#234)
- On Windows, added a workaround for FAT/exFAT filesystems that produce ERROR_INVALID_PARAMETER when querying file attributes. This affected status and symlink_status, which reported that files do not exist, and directory iterators, which failed to construct, as well as other dependent operations. (#236, #237)
Iterator:
- For C++11 and later, added support for perfect forwarding of values written to function_output_iterator. (PR#73)
- Added protection against writing to function_output_iterator a result of dereferencing another function_output_iterator.
LEAF:
- API breaking change: throw leaf::exception(....) now becomes leaf::throw_exception(....)
- Fixed a bug in support for a rare build configuration (exception handling enabled, diagnostics disabled)
- Using nullptr instead of 0 throughout
- Fixed pedantic warnings
Log:
- Bug fixes:
  - Fixed binding incorrect local address in UDP socket-based syslog_backend when IPv6 address is used for the syslog server. (#181)
  - Added a workaround for a bug in libstdc++ from gcc 11.2. When max_size_decor was used on a formatting stream, std::codecvt::do_length incorrectly accessed the input buffer and caused a buffer overflow.
- See changelog for more details.
Multi-index Containers:
- Maintenance work.
STLInterfaces:
- Fix #53: "missing 'typename' prior to dependent type name 'C::const_iterator'"
- Fix #54: "Concept check fails on .data() of a view on contiguous iterator_interface instantiations"
- New additions to make it easy to write views and view adaptors that work like, and interoperate with, the ones in the standard library:
  - Add workalikes for C++23's std::bind_back() and std::range_adaptor_closure for pre-C++23 code.
  - Add templates closure and adaptor to make writing view adaptors easier, following the examples in P2387.
System:
- When an error_code is converted to std::error_code and then back to error_code, the original is now restored, if possible.
- Reworked the conversion from error_category to std::error_category to avoid the one-time allocation that shows up on leak checkers.
- Added a constructor that allows replacing the source location of an error_code, and a corresponding assign.
- Added a converting constructor to result.
Unordered: Major update:
- Refactor internal implementation to be dramatically faster
- Allow final Hasher and KeyEqual objects
- Update documentation, adding benchmark graphs and notes on the new internal data structures
Utility:
- In string_view/string_ref, fixed max_size returning incorrect value. (#91)
- Removed noexcept specifier from string_view::compare as it may throw on some input arguments. (#94)
- In string_view/string_ref, added support for calling substr with no arguments. (#96)
- Added string_view::contains methods that were introduced in C++23. (#93)

Updated Tools

Build:
- Includes release of B2 version 4.9.2.

Compilers Tested

Boost's primary test compilers are:

Linux:
- Clang: 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 12.0.0
- Clang, C++11: 3.4, 11.0.0
- Clang, C++14: 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.0, 12.0.0
- Clang, C++17: 6.0.1, 7.0.0, 8.0.0, 9.0.0, 10.0.0, 11.0.0, 12.0.0
- Clang, C++20: 11.0.0, 12.0.0, 13.0.0
- GCC: 4.6.3, 11
- GCC, C++11: 4.7.3, 4.8.5, 11
- GCC, C++14: 5.4.0, 6.4.0, 7.3.0, 8.0.1, 9.1.0, 11
- GCC, C++17: 7.3.0, 8.0.1, 9.1.0, 11
- GCC, C++20: 8.0.1, 9.1.0, 10, 11
OS X:
- Apple Clang: 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

Acknowledgements

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

Version 1.79.0

Wed, 13 Apr 2022 14:22:59 +0000

Known Issues

These are patches from library authors which were found too late to be fixed in the release.

Boost.JSON array::erase can segfault, see #692. Patch.

New Libraries

No new libraries.

Updated Libraries

Asio:
- Added bind_allocator.
- Added file_base::sync_all_on_write flag.
- Added missing implementation of basic_file::release().
- Added per-operation cancellation support to signal sets.
- Exposed recycling_allocator as part of the public interface.
- Added the nodiscard attribute to a number of functions.
- Added OpenSSL 3.0 compatibility.
- Added support for adopting an existing SSL* into an ssl::stream<>.
- Enabled executor_work_guard<> in all build configurations.
- Enabled movable socket iostreams when using clang.
- Fixed bind_cancellation_slot and bind_executor compatibility with legacy completion tokens.
- Fixed associator specialisations for experimental::append and experimental::prepend.
- Fixed associated_allocator primary template.
- Fixed io_uring implementations of async_receive_from for sockets and write_some_at for files.
- Fixed io_uring feature detection.
- Fixed experimental::coro's per-operation cancellation.
- Fixed memory management in experimental::promise's type-erased completion handlers.
- Fixed move operator= implementation for ssl::stream.
- Fixed any_io_executor implementation to work when both BOOST_ASIO_USE_TS_EXECUTOR_AS_DEFAULT and BOOST_ASIO_SEPARATE_COMPILATION are defined.
- Fixed implementation of basic_socket::at_mark() when using the sockatmark() system call.
- Changed the recycling allocator to use the default alignment as the minimum alignment for allocations.
- Added a workaround for apparent coroutine codegen bug with Apple's clang.
- On Windows, changed the file support to open files using the same sharing mode as fopen().
- On Linux, fixed UNIX domain sockets implementation to correctly handle EAGAIN.
- Fixed implementation of experimental::basic_channel::reset() and experimental::basic_concurrent_channel::reset().
- Fixed potential undefined behaviour in the experimental::promise.
- Changed the co_spawn implementation to dispatch cancellation signals through the executor in some circumstances.
- Fixed various header inclusion issues.
- Fixed various warnings.
- A number of documentation enhancements, including:
  - Added an overview of Asio's asynchronous model.
  - Reworked reference and requirements documentation in terms of asynchronous model.
  - Updated documentation for dispatch(), post(), and defer().
  - Documented per-operation cancellation for serial ports.
  - Clarified the non-concurrency guarantees made for allocators.
  - Reverted the io_context reference documentation to use executor_work_guard.
  - Added more detailed reference documentation to make_strand(), make_work_guard(), ip::address_v4, ip::address_v6, experimental::basic_channel, and experimental::basic_concurrent_channel.
  - Re-arranged and extended the Overview documentation to cover recently added features.
- Added a C++11 example showing file descriptor passing over local sockets.
- Added C++14 examples of wrapping callback-based APIs in asynchronous operations.
- Consult the Revision History for further details.
Assert:
- source_location().file_name() and source_location().function_name() now return "" instead of "(unknown)".
- Added a source_location constructor from std::source_location.
- Changed BOOST_CURRENT_LOCATION to more closely match the behavior of std::source_location::current(), such as being usable at top level or as a default function argument.
Atomic:
- Fixed compilation for Universal Windows Platform (UWP). (#54)
- Added BOOST_ATOMIC_NO_DARWIN_ULOCK configuration macro. The macro affects compilation on Darwin systems and disables ulock-based implementation of waiting and notifying operations. This may be useful to comply with Apple App Store requirements. (#55)
Beast:
- Added missing include for file_body test.
- Fixed WebSocket handshake response on failure.
- Fixed open append mode for file_posix and file_win32.
- Fixed file open with append/append_existing flag on Windows
- Fixed clang-cl UTF8 path handling for file_win32 and file_stdio.
- Added ARM64 builds to drone CI.
- Fixed async_base documentation link.
- Added tests for file open in append/append_existing mode.
- Updated CI to include gcc 11, clang 12, msvc 14.3.
- Added individual tests to CMake workflow.
- 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.
Core:
- Made boost::pointer_traits SFINAE friendly, addressing LWG3545. (Glen Fernandes)
- Added boost::allocator_traits that uses the individual allocator access traits. This implementation supports C++03 and above. (Glen Fernandes)
- Updated the allocator access traits to support most of the C++11 allocator model in C++03. (Glen Fernandes)
- boost/iterator.hpp is deprecated and will be removed in a future release. The header defines boost::iterator template, which is equivalent to std::iterator in <iterator> header. However, since std::iterator is itself deprecated in C++17, users are advised to remove boost::iterator or std::iterator use from their code.
- Added boost::core::verbose_terminate_handler, a utility function intended to be passed to std::set_terminate that prints information about the uncaught exception to stderr.
Describe:
- Enabled unions in BOOST_DESCRIBE_STRUCT and updated examples to check std::is_union<T>.
- Added example of defining a fmtlib class formatter.
- Added example of defining a fmtlib enum formatter.
- Added example of printing pointers to members.
Filesystem:
- v3: path::replace_extension now works in terms of v3 definition of path::extension rather than v4.
- Fixed compilation of path appending and concatenation operators with arguments of types convertible to path or compatible string type. (#223)
- On POSIX systems that support fdopendir and O_NOFOLLOW and on Windows, remove_all is now protected against CVE-2022-21658. The vulnerability is a race condition that allows a third party process to replace a directory that is being concurrently processed by remove_all with a directory symlink and cause remove_all to follow the symlink and remove files in the linked directory instead of removing the symlink itself. (#224)
- On Windows, in remove and remove_all implementation, use POSIX semantics for file removal, when supported by the OS (Windows 10 1709 and later). When POSIX semantics is supported, the file name is removed from the filesystem namespace as soon as the file is marked for deletion, even if it is still open and in use. With legacy Windows semantics, the file name remains present in the the filesystem namespace until the last file handle to the file is closed, which allows the file marked for deletion to be opened and prevents creating new files with the same name. (#216)
- On Windows, remove and remove_all now support deleting read-only directories. Support for removing read-only non-directory files was added previously.
- On Windows, directory_iterator internal implementation has been reworked to better utilize modern Windows APIs, which may improve performance while handling symlinks.
- On Windows, initialize internal WinAPI function pointers early, if possible, to allow Boost.Filesystem operations to be invoked in global constructors. This is only supported on MSVC, GCC, Clang and compatible compilers.
- On Windows, resize_file should no longer fail with an error if the file to be resized is opened.
- Disabled use of the statx syscall on Android prior to 11.0 (API version 30). The syscall is blacklisted by seccomp and causes process termination in runtime. (#229)
- Deprecated: boost/filesystem/string_file.hpp header is deprecated and will be removed in a future release. The header is no longer included by boost/filesystem.hpp by default. Users are advised to implement the functionality themselves or migrate to other implementations.
- Deprecated: Windows CE support is deprecated and will be removed in a future release. Windows CE has been untested for many years and is likely non-functional.
Geometry:
- Major change
  - PR#977 Rescaling is turned off by default. This avoids many related bugs in set operations and buffer.
- Improvements
  - PR#923 Added algorithm closest_points for cartesian point/geometry.
  - PR#939 Added algorithm closest_points for other coordinate systems and geometry combinations excl. boxes.
  - PR#961 Added Web Mercator projection.
  - PR#966 More efficient cartesian distance strategy used in simplify.
- Solved issues
  - #956 Result of simplify algorithm with incorrect closure.
  - #962 Runtime error in R-tree deserialization due to load factor.
  - #971 R-tree insertion time impacted by use of long double on ARM platforms.
- Bugfixes
  - PR#936 Envelope of polygon containing pole.
  - PR#948 Spherical and geographic envelope for near meridian segments.
  - PR#974 Spheroidal normalization utilities for NaN coordinates.
  - Various fixes in set operations and buffer.
Integer:
- Optimized integer_log2 implementation to use bit operations internally. This allows to employ bit instructions available on most modern CPUs. (#31)
IO:
- Added boost::io::basic_nullbuf, a null stream buffer, and boost::basic_onullstream, a null output stream (Glen Fernandes).
Iterator:
- In counting_iterator, added support for built-in 128-bit integer types supported by gcc and clang and compatible compilers on some target platforms.
- Silenced gcc warnings about deprecated implicit copy assignment operator in counting_iterator.
JSON:
- Standalone mode of the library is removed. Users who wish to continue using standalone JSON can switch to the C++ Alliance fork.
- Add std::error_code overloads.
- Add boost::source_location to error_codes.
- Add support for JSON Pointer.
- Naturally grow string during serialization.
LEAF:
- Support for FreeRTOS and other embedded platforms
- Improved diagnostic information
- Improved configuration macros
- BOOST_LEAF_CHECK using statement expressions under __GNUC__
- Fixed symbol demangling bug
Log:
- General changes:
  - In text_file_backend, added support for appending to a previously written log file, when file rotation is used and log file names use file counters.
  - Breaking change: The file_collector interface has changed:
    
    scan_for_files method returns a scan_result structure that contains information collected during the scan;
    
    is_in_storage method added for testing if a path refers to a file within the target storage directory.
  - Added a new invoke_manip stream manipulator that can be used for injecting user's function into a stream output expression.
- Bug fixes:
  - Fixed file counter being set to zero if the user calls text_file_backend::scan_for_files multiple times, and the second and the following calls don't find any new files. (#179)
- See changelog for more details.
Multi-index Containers:
- Improved the efficiency of count operations in ranked indices from O(log(n) + count) to O(log(n)). Contributed by Damian Sawicki.
- Maintenance work.
Nowide:
- Fix compilation issues on some platforms (e.g. GCC 11 on MinGW-w64 and Cygwin)
- Fix missing include when using BOOST_USE_WINDOWS_H and WIN32_LEAN_AND_MEAN
- Add sanity check when using boost::nowide::stat with boost::nowide::stat_t
Optional:
- Fixed issue #98.
- Fixed issue #92.
- Added support for BOOST_NO_IOSTREAM.
- Now aligned storage uses unsigned char rather than char to avoid UB.
- Now using cv-unqualified value_type with placement new to avoid UB.
Predef:
- Version 1.14.0
- Add detection of LoongArch (from Zhang Na).
QVM:
- Added constexpr under C++17
- Improved single header distribution
Smart Pointers:
- Added boost::get_allocator_pointer to obtain the Allocator pointer from the result of boost::allocate_unique (Glen Fernandes).
System:
- Added a boost::source_location parameter to throw_exception_from_error.
- Added throw_exception_from_error overloads for errc::errc_t, std::error_code, std::errc, std::exception_ptr.
- result<T>::value now automatically supplies BOOST_CURRENT_LOCATION to throw_exception_from_error via a default argument.
- Added an errc::make_error_code overload taking a source location.
ThrowException:
- Added boost::throw_with_location, a more lightweight alternative of BOOST_THROW_EXCEPTION for programs that do not use Boost.Exception.
Unordered:
- All containers have been updated to support heterogeneous count, equal_range and find.
- All containers now implement the member function contains.
- erase_if has been implemented for all containers.
- All containers have been updated to support heterogeneous erase and extract.
- Changed behavior of reserve to eagerly allocate.
- Various warning fixes in the test suite.
- Update code to internally use boost::allocator_traits.
- Switch to Fibonacci hashing.
- Update documentation to be written in AsciiDoc instead of QuickBook.
Variant2:
- Added operator<< for monostate.
Wave:
- C++11 now required for building Wave itself
- Fixed bugs:
  - #135: Comma operators in array subscripts are deprecated in C++20
  - #137: Simple unknown directive => found_unknown_directive is not called, stripped of pound.
  - #138: Empty ifdef block does not emit line directive for missing whitespace
  - #143: Parsing __has_include() fails with trailing tokens
  - #145: Sanitizer complains about reset_version()
  - #147: bitwise operations between different enumeration types are deprecated

Updated Tools

Build:
- Includes release of B2 version 4.8.2.

Compilers Tested

Boost's primary test compilers are:

Linux:
- Clang: 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 12.0.0
- Clang, C++11: 3.4, 11.0.0
- Clang, C++14: 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.0, 12.0.0
- Clang, C++17: 6.0.1, 7.0.0, 8.0.0, 9.0.0, 10.0.0, 11.0.0, 12.0.0
- Clang, C++20: 11.0.0, 12.0.0, 13.0.0
- GCC: 4.6.3, 11
- GCC, C++11: 4.7.3, 4.8.5, 11
- GCC, C++14: 5.4.0, 6.4.0, 7.3.0, 8.0.1, 9.1.0, 11
- GCC, C++17: 7.3.0, 8.0.1, 9.1.0, 11
- GCC, C++20: 8.0.1, 9.1.0, 10, 11
OS X:
- Apple Clang: 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

Acknowledgements

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

Version 1.78.0

Wed, 08 Dec 2021 03:45:49 +0000

Known Issues

These are patches from library authors which were found too late to be fixed in the release.

Boost.Build silently skips installation of library headers and binaries in some cases, see #104.
- Fixed in PR#113, patch.
Boost.Atomic fails to build when targeting UWP, see #54. Patch.

New Libraries

No new libraries.

Updated Libraries

Asio:
- Added an io_uring backend that may optionally be used for all I/O objects, including sockets, timers, and posix descriptors.
- Added support for files, with new new classes for stream-oriented and random-access files. This feature currently supports I/O completion ports on Windows, and io_uring on Linux.
- Added support for portable pipes on POSIX and Windows (when I/O completion ports are available).
- Added support for registered buffers, which are optimised when using the io_uring backend.
- Added experimental support for channels, that may be used to send and queue completions as messages.
- Implemented improvements to experimental::coro.
- Disabled aligned_alloc on clang when using an MSVC runtime.
- Changed to use a faster implementation for ip::network_v4::canonical().
- Added template specialisations for common uses to improve compile time.
- Reduced the size of io_context executors to a single pointer.
- Increased the small object buffer size for execution::any_executor and any_io_executor.
- Fixed multi-signature handling when variadic templates are disabled.
- Fixed compatibility with new versions of gcc and clang.
- Fixed compilation on Solaris.
- Fixed defence against Qt-defined macros when building with MSVC.
- Improved error messages emitted by ssl facilities.
- Fixed bind_executor compatibility with completion tokens.
- Fixed build errors when BOOST_ASIO_USE_TS_EXECUTOR_AS_DEFAULT is defined.
- Added missing move assignment operator to awaitable<>.
- Fixed an access violation when using coroutines with MSVC, due to incorrect alignment of allocated memory.
- Fixed a cleanup issue in experimental::parallel_group that occured when the execution context was shut down with parallel operations still pending.
- Added clarifications to the documentation on concurrency hints.
- Added documentation on error handling techniques for C++20 coroutines.
- Fixed various warnings.
- Consult the Revision History for further details.
Assert:
- Added source_location::to_string.
Atomic:
- Use process-local futex operations on Android for non-IPC waiting and notifying operations.
- Added support for Linux targets that only define SYS_futex_time64 syscall, such as riscv32.
- Added a workaround for incorrect result of std::alignment_of on clang 8 for 64-bit types on 32-bit x86 targets.
- Added a ulock backend for waiting and notifying operations on Darwin systems since Mac OS 10.12, iOS 10.0, tvOS 10.0 or watchOS 3.0.
- On Windows, corrected discrepancy between atomic-type::always_has_native_wait_notify and the corresponding capability macros when targeting Windows 8 or later. The library will now directly use WaitOnAddress and related APIs from public headers and therefore require user to link with synchronization.lib if the user requires Windows 8 or later by defining BOOST_USE_WINAPI_VERSION, _WIN32_WINNT or similar macros. The library is linked automatically on compilers that support auto-linking (e.g. MSVC).
- Added support for types with padding bits, except unions, on compilers that provide a way to clear the padding bits. This feature is supported by gcc 11 and MSVC 14.2 (compiler version 19.27) and newer, as well as other compilers supporting similar intrinsics. On compilers that don't allow to clear the padding bits, types with padding are still generally not supported with the exception of 80-bit long double on x86 targets. A new BOOST_ATOMIC_NO_CLEAR_PADDING capability macro is defined to indicate when clearing the padding is not supported.
- Initializing constructors of atomic_ref and ipc_atomic_ref no longer use atomic instructions to clear the padding bits in the referenced object. This reduces the cost of the atomic reference construction.
- Initializing constructors of atomic and ipc_atomic are now constexpr for enums, classes and floating point types. For classes and floating point types, the constructors are constexpr if the compiler supports constexpr std::bit_cast, the type has no padding bytes and no padding is required to implement native atomic operations.
- In accordance with C++20, default constructors of atomic and ipc_atomic now perform value initialization of the contained object. For types without a user-defined default constructor, this means the default-constructed atomic will be zero-initialized.
- Added a workaround for compilation error on AIX caused by the assembler tool not supporting numeric labels. (PR#50)
- Added a workaround for compilation error with Visual Studio 2015 prior to Update 3. (#52)
- See changelog for more details.
Beast:
- This maintenance update brings minor bug fixes and updated CI reporting.
- Fixed security vulnerability CVE-2016-9840 in zlib implementation.
- Fixed WebSocket permessage_deflate implementation. This should result in an increase in compression performance when using Beast WebSockets.
- Removed the test stream and test framework's dependency on RTTI. You can now use our handy test stream to check your embedded asynchronous communications code!
- 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.
Core:
- Added a generic implementation to <boost/core/cmath.hpp>, enabled when BOOST_CORE_USE_GENERIC_CMATH is defined or when the platform does not provide the necessary facilities in <cmath>.
- Added boost::core::type_name, a utility function that returns the name of a type as a string.
- Added boost::span, a C++11 implementation of C++20's std::span (Glen Fernandes).
Describe:
- Added has_describe_enumerators, has_describe_bases, has_describe_members.
- Added enum_to_string, enum_from_string.
- Added relational and stream insertion operators.
- Added descriptor_by_name, descriptor_by_pointer.
DLL:
- Fixed missing #include, thanks to Denis Blank (PR#54)
- Dropped TravisCI in favor of GithubAction CI
Filesystem:
- v4: path::filename and path::iterator no longer return an implicit trailing dot (".") element if the path ends with a directory separator. Instead, an empty path is returned, similar to C++17 std::filesystem. This also affects other methods that are defined in terms of iterators or filename, such as path::stem, path::compare or lexicographical_compare. For example, path("a/b/") == path("a/b/.") no longer holds true. (#193)
- v4: path::lexically_normal no longer produce a trailing dot (".") element and omits a directory separator after a trailing dot-dot ("..") element in the normalized paths.
- v4: path append operations now consider root name and root directory in the appended path. If the appended path is absolute, or root name is present and differs from the source path, the resulting path is equivalent to the appended path. If root directory is present, the result is the root directory and relative path rebased on top of the root name of the source path. Otherwise, the behavior is similar to v3. (#214)
- path::lexically_normal now converts directory separators to preferred separators in the root name of the normalized paths.
- Optimized overloads of path::assign, path::append, path::concat and the corresponding operators to avoid unnecessary path copying and reduce the amount of code redundancy.
- On POSIX systems, fixed absolute(p, base) returning a path with root name base.root_name() if p starts with a root directory. In such a case p is already an absolute path and should be returned as is.
- create_directories no longer reports an error if the input path consists entirely of dot (".") and dot-dot ("..") elements. The implementation is no longer using recursion internally and therefore is better protected from stack overflow on extremely long paths.
- On Windows, remove now supports deleting read-only files. The operation will attempt to reset the read-only attribute prior to removal. Note that this introduces a possibility of the read-only attribute being left unset, if the operation fails and the original value of the attribute fails to be restored. This also affects remove_all. (#216)
- remove_all now returns static_cast< uintmax_t >(-1) in case of error, similar to C++17 std::filesystem.
- Fixed a linking error about unresolved references to Boost.ContainerHash functions when user's code includes boost/filesystem/path.hpp but not boost/container_hash/hash.hpp and the compiler is set to preserve unused inline functions. (#215)
- Added a workaround for MSVC and compatible compilers eliminating path globals cleanup in release builds. This could lead to a memory leak if Boost.Filesystem shared library was repeatedly loaded and unloaded in the process. (#217)
Geometry:
- Improvements
  - PR#894 Optimization and refactoring of rtree queries.
  - PR#913 DynamicGeometry and GeometryCollection support in various algorithms (undocumented for now).
  - PR#922 DynamicGeometry and GeometryCollection support in distance (undocumented for now).
- Solved issues
  - #867 Poor performance of rtree query iterator with nearest predicate for big k.
  - #870 Compilation error in boost::geometry::self_turns.
  - #896 Assertion failure in get_turns with BOOST_GEOMETRY_NO_ROBUSTNESS.
- Bugfixes
  - PR#906 Invalid result of buffer on macos-11 with clang-12.
  - PR#921 Compilation errors with c++20 (various compilers) and gcc-5.
  - Various fixes in set operations and buffer.
JSON:
- Standalone mode of the library is deprecated.
- Allow external libraries to forward declare value_to and value_from.
- Fixed signed integer overflow in number parsing.
- Add support for /Zc:implicitNoexcept- on MSVC.
Lambda2:
- Added special cases in operator<< and operator>> when the first argument is a stream, to allow std::cout << _1.
- Added operator->*.
- Added first, second.
Log:
- General changes:
  - Updated detection of std::codecvt specializations for char16_t and char32_t for compatibility with C++17 and later. (PR#159)
  - Added support for C++17 std::byte type to receive methods of the inter-process message queue.
  - On Windows, when building the library for Windows 8 or later, the library will use nt62 tag in the version namespace to denote the target OS ABI. For example, the version namespace could be named as v2_mt_nt62. This name will be part of all symbols exported by the library. Use the BOOST_USE_WINAPI_VERSION macro consistenly when building Boost and your code to request the minimum target Windows version.
  - Improved performance of SSSE3 and AVX2 implementations of the dump stream manipulator.
  - Added support for CMake build system. Only library build is supported at this moment, Boost.Build is still used for running tests.
- Bug fixes:
  - Fixed a race condition on POSIX systems in reliable_message_queue::open_or_create or the equivalent constructor. Multiple threads or processes calling open_or_create concurrently with sending or receiving messages from the same queue could end up corrupting the queue contents and potentially crashing the process. (#162)
  - Added a workaround for b2 install failing on Windows because of missing boost_log_setup library if BOOST_LOG_WITHOUT_SETTINGS_PARSERS is defined. (#164)
- See changelog for more details.
Math:
- Add support for cubic roots.
- Add support for constexpr versions of various standard library math routines.
- Add support for Bezier polynomials.
- Improve worst-case tanh-sinh integration performance.
- Disable inadvertant use of integral types in integration routines.
- Minor update for erf approximations when the result is with 2ulp of 1.
- Allow Bernoulli code to be used on platforms with no atomic integers.
- Improve the mode of the non-central Chi Squared distribution.
- Improve certain edge cases for <cstdfloat> complex-valued elementary functions, see #507.
Multi-index Containers:
- Added contains to key-based indices (issue #35).
- Added merge operations to key-based indices. The functionality goes beyond the standard specification for (unordered) associative containers in a number of ways, most notably:
  - The source index can be of any type, including non key-based indices.
  - Partial merge is provided: for instance, x.merge(y,first,last) merges only the elements of y within [first,last).
- Previous versions of splice for sequenced and random access indices were destructive, i.e. elements were copy-inserted into the destination and then erased from the source. Now, splice is based on node transfer much as merge in key-based indices, and has been similarly extended to accept source indices of any type: in fact, splice can be regarded as a frontend to the same functionality provided by merge in key-based indices. For reasons of backwards compatibility, the destructive behavior of splice has been retained in the case that the source and destination containers have unequal allocators.
- The fact has been documented that index iterator types do only depend on node_type and the position of the index in its multi_index_container, (except for hashed indices, where uniqueness/non-uniqueness is also a dependency). This has implications on the validity of iterators to elements transferred by merge or splice. This property is a variant of what has been called SCARY iterators in the C++ standard mailing lists. SCARYness is currently (August 2021) not mandated for standard containers.
- Iterator SCARYness is now also preserved in safe mode.
Multiprecision:
- Rework rational_adaptor to remove dependency on Boost.Rational and improve performance.
- Fix issue with type_traits and clang, see #383.
- Fixed buggy Lehmer's GCD routine, see #370.
- Fix mpc_complex constructors so that lossy conversions are explicit, see #363.
- Correct miscellaneous configuration issues (Intel intrinsic usage and Apple clang).
- Correct some iostream operators for unsigned char types.
- Correct mpq_rational conversions to integer types, see #342.
Nowide:
- Breaking Change: do_unshift for the UTF-32 specialization of utf8_codecvt now correctly returns noconv instead of ok
- Remove unnecessary branch in utf8_codecvt for UTF-16 output
- Suppress deprecation warnings in MSVC when using utf8_codecvt with unicode char types
- Fix possible double-free when setting a custom buffer (setbuf) after filebuf already allocated an internal buffer
PFR:
- Added missing #include <memory> for inclusion of std::addressof
- Fixed -Wzero-length-array warning when dealing with empty aggregates
- Fixed compilation on msvc compilers <= 1920 (thanks to Alexey Romanov aka @alexey-romanov)
- Added basic CMakeLists.txt support (thanks to @pdimov aka Peter Dimov)
- Multiple improvements for docs, including links to https://github.com/apolukhin/pfr_non_boost
- Added misc/strip_boost_namespace.sh script to remove boost:: and BOOST_ prefixes
Predef:
- Version 1.13.1
- Fix spelling of "epoch".
- Add missing parenthesis in sparc.h (from tkoecker).
- Update documentation to use Rouge code styling and Amber general style.
Regex:
- Breaking Change: Change \B to be the opposite of \b as per Perl behaviour.
- Change w32_regex_traits.hpp so that windows.h is no longer included.
- Fxed fuzzing related issues #151, #152, #153, #156.
System:
- Added support for source locations to error_code.
- Added error_code::to_string, error_condition::to_string, error_code::what.
- system_error::what() now contains the source location, if present.
- Added result<T, E = error_code>, a class holding either a value or an error, defined in <boost/system/result.hpp>.
Utility:
- Library documentation converted to QuickBook (thanks to Alan de Freitas, PR#79).
Variant2:
- Added <boost/variant2.hpp>.
- Added unsafe_get<I>.
- Added visit_by_index.
- Added operator<<.

Updated Tools

Build:
- Includes release of B2 version 4.7.2.

Compilers Tested

Boost's primary test compilers are:

Linux:
- Clang: 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 12.0.0
- Clang, C++11: 3.4, 11.0.0
- Clang, C++14: 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.0, 12.0.0
- Clang, C++17: 6.0.1, 7.0.0, 8.0.0, 9.0.0, 10.0.0, 11.0.0, 12.0.0
- Clang, C++20: 11.0.0, 12.0.0, 13.0.0
- GCC: 4.6.3, 11
- GCC, C++11: 4.7.3, 4.8.5, 11
- GCC, C++14: 5.4.0, 6.4.0, 7.3.0, 8.0.1, 9.1.0, 11
- GCC, C++17: 7.3.0, 8.0.1, 9.1.0, 11
- GCC, C++20: 8.0.1, 9.1.0, 10, 11
OS X:
- Apple Clang: 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

Acknowledgements

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

Version 1.77.0

Wed, 11 Aug 2021 14:25:13 +0000

New Libraries

Describe: A C++14 reflection library, from Peter Dimov. Provides macros for describing enumerators and struct/class members, and primitives for querying this information.
Lambda2: A C++14, dependency-free, single header lambda library, from Peter Dimov. Allows simple function objects to be constructed via expressions such as _1 + 5, _1 % 2 == 0, _1 > _2, or _1 == ' ' || _1 == '\t'.

Updated Libraries

Any:
- Added boost::anys::basic_any - a data type with customizable Small Object Optimization whose instances can hold instances of any type that satisfies ValueType requirements (many thanks to Ruslan Arutyunyan @rarutyun). If you are not sure that you really need it, then use boost::any instead.
- Started using GithubActions CI for additional testing
Asio:
- Added support for cancellation of individual asynchronous operations.
- Added the associator trait, used to generically forward associators.
- Changed all asynchronous operations implemented in Asio to invoke their completion handlers as rvalue references.
- Added support for asynchronous operations with multiple completion signatures.
- Added operator&& and operator|| for awaitable<>, to allow coroutines to be trivially awaited in parallel.
- Added the experimental::as_tuple completion token adapter.
- Added the experimental::append completion token adapter.
- Added the experimental::prepend completion token adapter.
- Added the experimental::deferred completion token, whicih allows deferred execution of asynchronous operations.
- Added the experimental::parallel_group class and experimental::make_parallel_group function.
- Added experimental::promise, which allows eager execution and synchronisation of asynchronous operations.
- Added the experimental::coro class template, a C++20 coroutine primitive with the ability to combine both asynchronous waiting (co_await) and yielding (co_yield).
- Added move assignment to ssl::stream<>.
- Changed co_spawn to dispatch the coroutine's initial step to the executor.
- Enabled additional optimisations for any_executor and any_io_executor when used with asynchronous operations.
- Added the nodiscard attribute to awaitable<>.
- Increased the number of cached slots in the default recycling allocator.
- Changed the default allocator behaviour to respect alignment requirements, to support over-aligned types.
- Ensured the result strings are always initialised in reverse name resolution.
- Fixed recursive template instantiation issues in use_awaitable_t::executor_with_default.
- Fixed the any_io_executor equality operators to correctly return a result based on the target executor.
- Fixed strand<> to avoid using a potentially moved-from executor.
- Ensured gcc tests are not used for clang when detecting compiler features.
- Disabled coroutines support for the clang shipped with MSVC.
- Fixed compatibility with recent LibreSSL when OPENSSL_NO_SSL_INTERN is defined.
- Fixed posix::basic_stream_descriptor move operations to work with non-defaulted executors.
- Consult the Revision History for further details.
Atomic:
- Added make_atomic_ref and make_ipc_atomic_ref factory functions for constructing atomic reference objects.
- Added C++17 template argument deduction guides for atomic_ref and ipc_atomic_ref to allow omitting template arguments when they can be deduced from constructor arguments.
Beast:
- This maintenance update brings minor bug fixes and updated CI reporting.
- 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.
Conversion:
- boost::implicit_cast is now constexpr (#25).
- Fixed broken links (PR#23).
- Started using GithubActions CI for additional testing
Core:
- boost/core/uncaught_exceptions.hpp has been modified for compatibility with Mac OS 10.4 and older. (PR#92)
DLL:
- More runtime checks for malformed ELFs in boost::dll::library_info
- In boost::dll::library_info use info from .dynsym ELF section if .symtab is empty or missing
- List protected ELF symbols in boost::dll::library_info as they are available for import (#50)
- Remove unneeded convert from wchar_t to char on POSIX environment, thanks to Vladislav Shchapov (PR#49)
- Started using GithubAction CI for additional testing
Filesystem:
- Introducing Boost.Filesystem v4. This new version of the library removes all deprecated features of v3 and also makes a number of breaking API changes intended to make Boost.Filesystem more compatible with std::filesystem introduced in C++17. The differences are described in the release notes and documentation using v3 and v4 tags and are also summarised in a separate section. Users can select Boost.Filesystem version by defining BOOST_FILESYSTEM_VERSION macro to either 3 or 4 when compiling their code. There is no need to separately compile Boost.Filesystem for each library version - a single binary supports both v3 and v4. Users should avoid using both v3 and v4 in the same application as this can lead to subtle bugs. Currently, v3 is the default. In a future release v4 will become the default, and eventually v3 will be removed. v4 is functional, but it is still a work in progress and there may be breaking API changes in the future.
- v4: path::filename, path::stem and path::extension no longer consider root name or root directory of the path as a filename if the path only consists of those components. For example, on Windows path("C:").filename() used to return "C:" and path("C:\\").filename() used to return "\" and both will return an empty path now. (#88, #194)
- v4: path::stem and path::extension no longer treat a filename that starts with a dot and has no other dots as an extension. Filenames starting with a dot are commonly treated as filenames with an empty extension. The leading dot is used to indicate a hidden file on most UNIX-like systems. (#88)
- New: Improved support for various path prefixes on Windows. Added support for local device prefix ("\\.\") and experimental support for NT path prefix ("\??\"). The prefixes will be included in the root name of a path. Note that using the prefixes with Boost.Filesystem v3 can lead to surprising results (e.g. path("\\\\.\\").stem() == "\\\\"). It is recommended to use the prefixes only with Boost.Filesystem v4.
- Reworked path::lexically_normal implementation to eliminate some cases of duplicate dot (".") elements in the normalized paths.
- New: Added runtime detection of the statx and getrandom system calls on Linux. This can be useful if the syscall is present at compile time but fails with ENOSYS at run time (for example, in Docker containers that restrict the syscall, even if available on the host). (#172)
- New: Added support for disabling usage of various system APIs at library build time. This can be useful when a certain API is detected as present by the library configuration scripts but must not be used for some reason (for example, when runtime detection does not work on the target system). See the description of configuration macros in the library documentationfor for more details.
- New: Added copy_options::synchronize_data and copy_options::synchronize options for the copy_file operation. These options allow to synchronize the written data and attributes with the permanent storage. These options are expensive in terms of performance, but allow to ensure reliability of the copied data. Note that copy_file performed implicit data synchronization on POSIX systems since Boost.Filesystem 1.74.0. This release adds support for more platforms and disables data synchronization by default while allowing the caller to explicitly request it. (#186)
- Added handling of EINTR error code on POSIX systems for some system calls issued internally. In particular, EINTR could have been ignored on close, which on HP-UX would result in a leaked file descriptor.
- In the copy_file implementations based on Linux sendfile and copy_file_range system calls, added handling of error codes indicating that a particular filesystem does not support the system call and fall back to the generic read/write loop. This should fix copy_file failing on eCryptFS and possibly other filesystems. (#184)
- The copy_file_range system call is now used since Linux kernel 4.5, whereas previously it was only enabled since 5.3. The copy_file implementation will fall back to sendfile or read/write loop if copy_file_range fails to copy a given file across filesystems.
- The copy_file implementations based on Linux sendfile and copy_file_range system calls will not be used on filesystems that are known to contain files with generated content. These system calls are incompatible with such files, and copying them would result in zero-sized files. The generic read/write loop will be used instead. Currently, the blacklisted filesystems are: procfs, sysfs, tracefs and debugfs.
- In the copy_file implementation based on read/write loop, increased the maximum size of the buffer used for temporary storage and take into account the target filesystem block size for more optimal performance.
- On Windows CE, calling current_path to obtain the current path for a process will now fail with an error instead of returning successfully with a root path. This platform does not support current directory. Changing the current path was already failing similarly in previous releases of Boost.Filesystem.
- In canonical, fixed the check for a symlink referencing a directory above root, if an earlier symlink was resolved to an absolute path with a different root from the original path.
- In canonical, added a limit for the maximum number of symlinks that can be resolved during the call. The limit is currently at least 40 symlinks.
- On Windows, canonical and weakly_canonical will now use path::preferred_separator for the root directory separator in the resulting paths. This fixes "file not found" errors caused by Windows API not handling generic separators in UNC paths and paths that start with the Win32 filesystem prefix ("\\?\"). (#87, #187)
- New: Added weakly_canonical overloads taking base path as an argument.
- On Windows, weakly_canonical no longer fails with an error if the input path contains elements that do not exist in the filesystem but are cancelled by a subsequent dot-dot ("..") element. For example, weakly_canonical("C:\\a\\..") would previously fail if "C:\a" directory did not exist. (#201)
- In read_symlink on Windows, corrected reparse point handling. The operation would return an empty path for some mount points (for example, created by Box cloud storage driver) and directory junction points that had empty print names. The new implementation now parses substitute name of the reparse point and attempts to reconstruct a Win32 path from it. (#187)
- On Windows, file streams provided in boost/filesystem/fstream.hpp will use wide character paths on libc++ versions 7.0 and higher, when the standard library supports opening files with wide character paths. (#181)
- On Windows, creating symlinks should no longer require elevated privileges, if Windows is configured in Developer mode.
- With some compilers, global objects used internally in Boost.Filesystem are now destroyed after user's global destructors are called. This allows to call Boost.Filesystem methods during the program termination stage. In particular, this concerns the path locale that is used for character code conversion and can be installed by calling path::imbue. The supported compilers include MSVC, GCC and Clang, as well as other compilers that support customizing program initialization order through #pragma section (for MSVC-compatible compilers) or __attribute__ ((init_priority)) (for GCC-compatible compilers).
Geometry:
- Improvements
  - PR#812 Umbrella strategies for distance and comparable_distance (undocumented for now).
  - PR#840 Umbrella strategies for various algorithms (undocumented for now).
  - PR#850 Introduced DynamicGeometry and GeometryCollection concepts and support in some algorithms (undocumented for now).
  - PR#855 Various improvements related to strategies. Default strategies are now included with algorithms.
- Solved issues
  - #865 Exception thrown in rtree serialization.
  - #439 Invalid box spherical area computation.
  - #838 Invalid result of union_().
  - #851 Invalid geographic disjoint segment/box result.
  - #861 Invalid result of intersection().
- Bugfixes
  - PR#832 Fixed box spherical and geographic area computation.
  - PR#853 Fixed geographic disjoint segment/box.
  - PR#866 Fixed serialization of rtree containing lesser number of elements in root node than minimum.
  - PR#886 Fixed knn rtree query bug causing it to be slow for big k.
  - Various fixes in set operations and buffer.
JSON:
- value_to supports TupleLike types.
- value_to and value_from support std::array and similar types.
- Implicit conversion operator from string to std::string_view.
- std::hash specializations for json types.
- Fixed allocation errors in object and key_value_pair.
- Fixed crash when constructing array from a pair of iterators that form an empty range.
LexicalCast:
- Fixed assignment to an int of a floating point value that is out of representable range for int.
- Started using GithubActions CI for additional testing
Log:
- Fixed compilation for riscv32 target. (PR#150)
Mp11:
- Added mp_intersperse, mp_split, mp_join
Multi-index Containers:
- Maintenance work.
Nowide:
- Allow for usage of iostream classes before main (best effort, works for most environments)
- Fix initialization of rdbuf in cin/cout/cerr for redirected input/output
- Fix corner case in cin::unget() after using putback()
- Fix possibly delayed close of filebuf after move assignment
- Improve performance of utf8_codecvt
PFR:
- A MurMur Hash based implementation of hash_combine() is now used to reduce collisions count and improve quality of boost::pfr::hash_value()
- Visual Studio 2017 now supported in C++14 mode (thanks to Denis Mikhailov aka @denzor200)
- Issues found by inspect tool were fixed
- Fixed some warnings, including removal of extra semicolons in include/boost/pfr/detail/fields_count.hpp (#72)
- Added a compile time assert for inherited types (thanks to Denis Mikhailov aka @denzor200)
- Reflection of aggregates with non movable fields is now possible if guaranteed copy elision is on
- Fixed spelling issues
- Started using GithubActions CI for additional testing
PropertyTree:
- This is a maintenance release.
- Extend compiler coverage in CI.
- Fix Boost compatibility for CMakeLists.txt.
System:
- The conversion operator from error_category to std::error_category has been improved and no longer requires <map> or <mutex>.
- The comparison operators of error_category are now inline friends instead of member functions (a side effect of the previous change.)
- error_condition now defers calling generic_category() to avoid instantiating the object until it's actually needed.
- error_condition::failed and error_condition::message have been undeprecated, and operator bool() now once again returns failed().
- The system category now doesn't call generic_category(), to avoid instantiating the object.
- The return value of default_error_condition changes in some cases into an error_condition from the generic category, instead of from the system category. This happens on POSIX when the input error_code is from the system category and does not correspond to any errc_t value.
- The interoperability of error_code and std::error_code has been improved substantially. It is now possible to construct boost::system::error_code from std::error_code, and it's possible to pass boost::system::error_code to functions taking std::error_code&.
- A stream insertion operator for error_condition has been added.
Uuid:
- Added to_chars for writing uuid strings without allocating (PR#116)

Updated Tools

Build:
- Includes release of B2 version 4.6.1.

Compilers Tested

Boost's primary test compilers are:

Linux:
- Clang: 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 12.0.0
- Clang, C++11: 3.4, 11.0.0
- Clang, C++14: 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 5.0, 12.0.0
- Clang, C++17: 6.0.1, 7.0.0, 8.0.0, 9.0.0, 10.0.0, 11.0.0, 12.0.0
- Clang, C++20: 11.0.0, 12.0.0, 13.0.0
- GCC: 4.6.3, 11
- GCC, C++11: 4.7.3, 4.8.5, 11
- GCC, C++14: 5.4.0, 6.4.0, 7.3.0, 8.0.1, 9.1.0, 11
- GCC, C++17: 7.3.0, 8.0.1, 9.1.0, 11
- GCC, C++20: 8.0.1, 9.1.0, 10, 11
OS X:
- Apple Clang: 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

Acknowledgements

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

Version 1.76.0

Fri, 16 Apr 2021 21:05:27 +0000

New Libraries

No new libraries

Updated Libraries

Asio:
- Added ip::scope_id_type type alias.
- Added ip::port_type type alias.
- Added std::hash specialisations for IP addresses.
- Added std::hash specialisations for ip::basic_endpoint<>.
- Refactored SFINAE usage to improve compile times.
- Added friendship support to customisation points, and made most customisations private.
- Changed any_io_executor to a "strong typedef"-style class.
- Fixed experimental::as_single to work with handler hook deprecation.
- Ensured pthread condition variable attributes are cleaned up on all platforms.
- Clarified thread safety notes on sockets and descriptors.
- Ensured errno is not overwritten if socket() fails on macOS/FreeBSD.
- Fixed work tracking for io_context and thread_pool executors when move-assigned.
- Ensured internal call_stack objects are accessed only from implementation files.
- Fixed I/O object move-assignment to ensure the executor is left in a valid state.
- Fixed detection of compiler support for defaulted template argument on functions with MSVC.
- Prevented the blocking.always property from being used with strand<>, as it did not produce the correct semantics.
- Removed deprecated file asio/impl/src.cpp.
Atomic:
- Fixed compilation with MSVC for ARM. (PR#49)
Beast:
- This update brings minor bug fixes and revamped CI reporting.
- 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.
Bind:
- Add support for using the standard C++11 placeholders with boost::bind.
- Update boost::apply to use variadic templates and perfect forwarding.
Container:
- Added [[no-discard]] attribute in all containers to catch bugs related to unused return values.
- Replaced default standard exception classes with Boost.Container own classes, reducing considerably the included files overhead. Example: in MSVC 19 boost/container/vector.hpp preprocessed file size reduces from 1,5MB to 930KB. If you still want to use standard exception classes, you can define BOOST_CONTAINER_USE_STD_EXCEPTIONS before using any Boost.Container class.
- Fixed bugs/issues:
Core:
- Add implicit conversion between compatible reference wrappers.
- Add boost/core/cmath.hpp, a portable implementation of the floating point classification functions from <cmath>.
- Add boost/core/bit.hpp, a portable implementation of the C++20 standard header <bit>.
- Fix BOOST_TEST_EQ, BOOST_TEST_NE for character types under C++20.
- Revise allocator access utilities (now support VS2013, and no workarounds use allocator_traits.)
DLL:
- BREAKING CHANGE: boost::dll::import was renamed to boost::dll::import_symbol to avoid collision with C++20 import keyword.
- Updated docs, including FAQ section.
Filesystem:
- Updated compatibility with WASI platform. (PR#169)
- Fixed an exception being thrown by path::remove_filename if the path is "////". (#176)
- Fixed create_directories disregarding errors from file status query operations issued internally. This could result in incorrect error codes returned by create_directories. (#182)
Geometry:
- Improvements
  - PR#670 New IOs to_wkt() and from_wkt() (thanks to Baidyanath Kundu).
  - PR#756 Non cartesian and robust convex hulls.
  - PR#768 Umbrella strategies for relops, setops, index, buffer and more (undocumented for now).
  - PR#797 New azimuth() algorithm.
  - PR#801 Improved accuracy in geographic area computations.
  - PR#820 Parameter scale added to svg_mapper.
- Bugfixes
  - PR#808 Fixed compilation error with rtree serialization enabled (thanks to Tristan Carel).
  - PR#815 Fixed issue in buffer().
  - Various fixes in set operations and buffer.
- Breaking changes
  - Removed strategy convex_hull::graham_andrew.
GIL:
- BREAKING: In next release, we are going to drop support for GCC 5. We will also change the required minimum C++ version from C++11 to C++14.
Histogram:
- This release contains critical fixes, please check that your results are not affected.
- See Release Notes for details.
Intrusive:
- Reduced compile-time dependencies:
  - linear_slist_algorithms use a simple node_ptr instead of std::pair on return.
  - list/slist use operator </operator == instead of std::equal_to/std::less.
- Fixed GitHub #54: set.rbegin() looks like O(log(N))
Interprocess:
- Added wchar_t API support for named resources in operating systems that offer native wide character API (e.g. Windows). The following classes were updated with wchar_t name support:
  - file_mapping
  - managed_mapped_file
  - managed_shared_memory
  - managed_windows_shared_memory
  - shared_memory_object
  - windows_shared_memory_object
  - file_lock
  - named_condition
  - named_condition_any
  - named_mutex
  - named_recursive_mutex
  - named_semaphore
  - named_sharable_mutex
  - named_upgradable_mutex
  - message_queue
- Added BOOST_INTERPROCESS_FORCE_NATIVE_EMULATION macro option to disable the use of generic emulation code for process shared synchronization primitives instead of native POSIX or Winapi functions.
- Fixed bugs:
JSON:
- Security Report from Bishop Fox.
- (#481) Refactored value_from implementation; user customizations are now always preferred over library-provided overloads.
- (#484) Fix imprecise parsing for some floating point numbers.
- (#485) Fix link errors in standalone mode, when used alongside Boost.
- (#497) Fix Boost.Build builds on GCC 4.8.
LexicalCast:
- Dropped dependency on Boost.Math (thanks to Peter Dimov #37, #39).
- Fixes for the CI and coverage (thanks to Sam Darwin from "The C++ Alliance" #38, #42).
Log:
- Bug fixes:
  - Corrected a formal race condition in the thread-safe log record queue implementation used in the unbounded_fifo_queue policy of the asynchronous_sink frontend. The race could be detected by TSAN, but it was not a real problem on most current CPU architectures and compilers. (#139)
  - When copying a logger with a channel attribute (e.g. channel_logger), the channel attribute is now deep-copied from the original logger. This means that modifying the channel in the new logger will no longer affect the original logger.
  - Replaced the use of std::allocator<void> in template parameters with a new tag type boost::log::use_std_allocator to silence libc++ warnings about the former being deprecated in C++17 and later. The tag indicates that the instantiated template should be using a specialization of std::allocator internally to allocate dynamic memory, so the change has no functional effect. (#141)
  - Boost.Log no longer defines __MSVCRT_VERSION__ macro on MinGW and MinGW-w64. Defining this macro caused incompatibility with UCRT, which is available as an option in recent MinGW-w64. (PR#149)
- See changelog for more details.
Math:
- Breaking Change: C++03 support is now removed, a C++11 or later conformant compiler is now required to use this library.
- Added Z-test.
- Added execution policy support to univariate and bivariate statistics: enables parallel execution (requires C++17 and <execution>).
- Big update/improvement on CI testing.
- Bivariate statistics now have integer support.
- T-Test now has integer support.
- Linear regression now has integer support.
- Correct PDF of the beta distribution at the endpoints.
- Correct use of Stirling's approximation in certain multiprecision cases, fixes #396.
- Eliminate -Wimplicit-int-float-conversion on clang.
- Fix some constexpr issues in quaternion/octonion.
- Minor performance fix to tanh_sinh integration.
- Update hypergeometric functions internal scaling to allow for 64-bit (long long) exponents with multiprecision types.
Move:
- Git Issue #35: "New nothrow move traits are incomplete".
Multiprecision:
- BREAKING CHANGE: Massive refactoring and code simplification makes C++11 an absolute requirement.
- Use BOOST_TRY/CATCH in headers so code can be used in exception-free environments.
- Correct corner case in pow, fixes #277.
- Correct exception type thrown to match docs in lsb/msb: fixes #257.
- Allow moves and operators between related but different types (ie types with the same allocator), fixes #278.
Nowide:
- Fix discarding of characters for text file streams when seek or sync functions are used and newlines were converted (e.g. on Windows)
- Fix potential use-after-free bug when reusing (via open) a file stream that has been closed
- Fix potential invalid memory access when using a file stream that has been moved or swapped to where the source had a put-back character or was set to unbuffered mode
- Fix compatibility with ucrt runtime by not defining __MSVCRT_VERSION__
- Known issues: Read performance for text files is degraded. Binary files and writing is unaffected.
Optional:
- Fixed MSVC warning C4702.
Outcome:
- Announcements:
  - BREAKING CHANGE: After a year and three major Boost releases announcing this upcoming change, this is the FIRST RELEASE of the v2.2 branch. This branch has a number of major breaking changes to the Outcome v2.1 which shipped in Boost 1.75 and earlier, see the documentation for details.
- Enhancements:
  - VS2019.8 changed how to enable Coroutines, which caused Outcome to not compile on that compiler.
  - If on C++ 20, we now use C++ 20 [[likely]] instead of compiler-specific markup to indicate when TRY has likely success or failure.
  - BREAKING CHANGE: Previously the value of spare_storage(const basic_result|basic_outcome *) noexcept was not propagated over BOOST_OUTCOME_TRY, which causes things like stack backtraces captured at the point of construction of an errored result to get dropped at every TRY point. This has been fixed by adding an optional spare_storage to success_type<T> and failure_type<T>, as well as to auto success(T &&, ...) and auto failure(T &&, ...).
- Bug fixes:
  - Boost.Outcome should now compile with BOOST_NO_EXCEPTIONS defined. Thanks to Emil, maintainer of Boost.Exception, making a change for me, Boost.Outcome should now compile with C++ exceptions globally disabled. You won't be able to use boost::exception_ptr as it can't be included if C++ exceptions are globally disabled.
  - BREAKING CHANGE #244 It came as a shock to learn that BOOST_OUTCOME_TRY had been broken since the inception of this library for certain corner case code, which required a breaking change in how TRY works. See the changelog in the documentation for more detail.
Parameter:
- Added a workaround for MSVC 2015 code miscompilation when an rvalue was used as a default value of a named parameter of a function. (PR#109, #132)
PFR:
- Fixed reflection of types with missing const in SFINAE expressions in template constructor. Now reflection of aggregates with std::optional<std::chrono::duration<???>> fields works on any Standard Library implementation, even if LWG3050 is not fixed.
- Comparison functions are now constexpr #52
- Fixed numerous typos in docs (thanks to Phil Miller #63)
PolyCollection:
- Worked around GCC bug affecting GCC versions 9.3-10.2 (issue #20).
Predef:
- Version 1.13
- Add ARCH_PPC_64 predef.
- Fix ARCH_WORD_BITS* redefinition warnings/errors.
- Add ARCH_E2K, Elbrus 2000, architecture from Konstantin Ivlev.
- Fix not handling recent C++ version that go above 10.x version.
- Version 1.12
- Switch to using the endian.h header on OpenBSD. (Brad Smith)
- Fix not handling recent versions of stdcxx that go above version 9.
- Fix including sub-BSD OS headers directly causing redef warnings.
- Add CI testing of direct inclusion of all headers.
- Add CI testing on FreeBSD for clang and gcc.
- Add WORD_BITS set of predefs to detect the architecture word size. Initial implementation inspired by submission from Mikhail Komarov.
- Add CI testing for Cygwin 32 and 64.
PropertyTree:
- Property Tree has a new maintainer.
- Fix usage of deprecated Boost.Bind features.
- Link to Wikipedia fixed.
- Use BOOST_OVERRIDE to fix GCC warnings.
- Add extensive CI testing.
Regex:
- Regex is now header only except in C++03 mode.
- Support for C++03 is now deprecated.
- The library can now be used "standalone" without the rest of Boost being present.
Stacktrace:
- Better support for pre-C++11 builds on clang #102.
- Bigger warning for do not use boost::stacktrace::stacktrace in signal handlers #71.
TypeTraits:
- Fix for Visual Studio managed code projects.
Variant2:
- Improved generated code for the double buffered case.

Updated Tools

Build:
- Includes release of B2 version 4.4.1.

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, 9.0.0, 10.0.0, 11.0.0
- 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, 9.0.0, 10.0.0, 11.0.0
- Clang, C++17: 5.0.2, 6.0.1, 7.0.0, 8.0.0, 9.0.0, 10.0.0, 11.0.0
- 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, 11.0.0
- Apple Clang, C++11: 9.0.0, 9.1.0, 10.0.0, 11.0.0
- Apple Clang, C++14: 9.0.0, 9.1.0, 10.0.0, 11.0.0
- Apple Clang, C++17: 9.1.0, 10.0.0, 11.0.0
- Apple Clang, C++1z: 9.0.0
- Apple Clang, C++2a: 10.0.0, 11.0.0
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.