Boost C++ Libraries of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Version 1.74.0

Version 1.74.0 beta 1

July 16th, 2020 04:37 GMT


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New Libraries

  • STLInterfaces: A library of CRTP bases to ease the writing of STL views, iterators, and sequence containers, from Zach Laine.
  • TODO

Updated Libraries

  • Asio:
    • Added an implementation of the proposed standard executors (P0443r13, P1348r0, and P1393r0).
    • Added support for the proposed standard executors to Asio's I/O facilities.
      • The supplied executors now meet the requirements for the proposed standard executors. These classes also continue to meet the existing requirements for the Networking TS model of executors.
      • All I/O objects, asynchronous operations, and utilities will interoperate with both new proposed standard executors, and with existing Networking TS executors.
      • The any_io_executor type alias has been introduced as the default runtime-polymorphic executor for all I/O objects. This defaults to the execution::any_executor<> template. If required for backward compatibility, BOOST_ASIO_USE_TS_EXECUTOR_AS_DEFAULT can be defined to use the old asio::executor polymorphic wrapper instead.
      • Support for the existing Networking TS model of executors can be disabled by defining BOOST_ASIO_NO_TS_EXECUTORS.
    • Added converting move construction and assignment to basic_waitable_timer.
    • Enabled C++20 coroutine support when using gcc 10.
    • Added overloads of co_spawn that launch an awaitable.
    • Added a new constructor overload to use_awaitable_t's default executor adapter, to enable conversion between executor types.
    • Added support for using detached_t as a default completion token, by adding members as_default_on() and as_default_on_t<>.
    • Added a move constructor to ssl::stream<>.
    • Changed ssl::stream<> write operations to linearise gather-write buffer sequences.
    • Added compile-time detection of the deprecated asio_handler_invoke, asio_handler_allocate, and asio_handler_deallocate hooks, when BOOST_ASIO_NO_DEPRECATED is defined.
    • Implemented a number of performance optimisations.
    • Added source location support to handler tracking.
    • Implemented various improvements to the tool.
    • Added the tool, which processes handler tracking output to produce a list of "live" handlers.
    • Added the tool, which filters handler tracking output to include only those events in the tree that produced the nominated handlers.
    • Added changes for clang-based Embarcadero C++ compilers.
    • Fixed a deadlock that can occur when multiple threads concurrently initialise the Windows I/O completion port backend.
    • Fixed async_compose to work with copyable handlers when passed by lvalue.
    • Fixed completion signature deduction in co_spawn.
    • Removed a spurious Executor base class from the executor_binder implementation.
    • Various fixes and improvements in the documentation and examples.
    • Consult the Revision History for further details.
  • Beast:
    • This update brings bug fixes and support for the following changes changes in Boost.Asio:
    • Beast supports BOOST_ASIO_NO_DEPRECATED. Define this to help identify areas of your Beast and Asio code which use deprecated Asio interfaces.
    • Beast also supports BOOST_ASIO_NO_TS_EXECUTORS. Define this to identify uses of executors from the now potentially outdated Networking TS
    • Asio will use the Standard Executors model by default. You can prevent this behaviour by defining BOOST_ASIO_USE_TS_EXECUTOR_AS_DEFAULT in which the Networking TS model will be used by default. Setting this flag does not prevent a program from using executors from the Standard Executors model explicitly.
    • 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.
  • Bimap:
    • Correct allocator usage (fixes C++20 compilation). (Glen Fernandes)
  • Config:
    • Implement BOOST_NO_CXX11_OVERRIDE and BOOST_OVERRIDE. (Glen Fernandes)
  • Core:
    • Implemented the allocator access utilities which provide a replacement for allocator_traits with individual traits and functions for each facility. They support the C++11 allocator model when possible and provide a fallback for C++98 compatibility. These are now used in Circular_Buffer, Wave, Lockfree, Heap, Smart_Ptr, Dynamic_Bitset, Format, Bimap and more. (Glen Fernandes)
  • DLL:
    • Multiple fixes for the library_info work on empty shared objects.
    • Compilation fixes for C++98 and C++11 modes (#28).
    • Fixes for smart_library manglings (thanks to XiaLiChao82 #37).
  • Endian:
    • Enabled scoped enumeration types in endian_reverse.
    • Enabled bool, enum, float, double in endian_reverse_inplace.
    • Added an overload of endian_reverse_inplace for arrays.
  • Flyweight:
    • Maintenance work.
  • Format:
    • Correct allocator usage (fixes C++20 compilation). (Glen Fernandes)
  • GIL:
    • Added
      • Added new constructor initializing any_image from r-value reference to any image (PR#486).
      • Implemented mechanism to reverse kernel_2d (PR#489).
    • Changed
      • Replace Boost.Variant with Boost.Variant2 (PR#474).
      • Use perfect forwarding from apply_operation to visit (PR#491).
    • Removed
      • Removed dependency on Boost.Variant
    • Fixed
      • Fixed invalid conversion from RGB8 to CMYK32 due to overflow (PR#470).
      • Fixed image constructor from other image (PR#477).
      • Fixed error plane_view_t is not a class or namespace name (PR#481).
      • Fixed interleaved_view factory using point<std::ptrdiff_t> for dimension (PR#487).
      • Fixed documentation replacing uses MPL with MP11 in tutorial (PR#494).
      • Fixed missing header in numeric/kernel.hpp to make it self-contained (PR#502).
    • Acknowledgements
      • Samuel Debionne, Pranam Lashkari, Mateusz Loskot, Debabrata Mandal
  • Heap:
    • Correct destruction of top node in skew_heap. (Glen Fernandes)
    • Correct and simplify allocator use. (Glen Fernandes)
  • LexicalCast:
    • Fixed warnings on missing override (thanks to EugeneZelenko #35, #34).
    • Fixes for the the Embarcadero compilers (thanks to Edward Diener).
  • Mp11:
    • Improved compilation performance of mp_with_index<N> for large N.
    • Added tuple_transform (contributed by Hans Dembinski.)
  • Multi-index Containers:
    • Added node extraction and insertion following the analogous interface of associative containers as introduced in C++17. This feature has also been extended to non key-based indices, in contrast to C++ standard library sequence containers, which do not provide such functionality.
    • Clarified documentation on read/write key extractors (issue #32).
    • Maintenance work.
  • Nowide:
    • The library now requires a C++11-compliant compiler and stdlib
    • LFS: Add support for files > 2 GB where the underlying system supports it
    • Generic UTF conversion functions are now available in the boost::nowide::utf namespace
    • Add support for stat with UTF-8 paths
  • Outcome:
    • Announcements:
      • The v2.1 branch is expected to be retired end of 2020, with the v2.2 branch becoming the default. You can use the future v2.2 branch now using better_optimisation. This branch has a number of major breaking changes to Outcome v2.1, see the front page for details.
    • Enhancements:
      • BREAKING CHANGE void results and outcomes no longer default construct types during explicit construction. Previously if you explicitly constructed a result<T> from a non-errored result<void>, it default constructed T. This was found to cause unhelpful surprise, so it has been disabled.
      • New macro OUTCOME_ENABLE_LEGACY_SUPPORT_FOR. The macro OUTCOME_ENABLE_LEGACY_SUPPORT_FOR can be used to enable aliasing of older naming and features to newer naming and features when using a newer version of Outcome.
      • Concepts now have snake case style naming instead of camel case style. When Outcome was first implemented, it was thought that C++ 20 concepts were going to have camel case style. This was changed before the C++ 20 release, and Outcome's concepts have been renamed similarly. This won't break any code in Outcome v2.1, as compatibility aliases are provided. However code compiled against Outcome v2.2 will need to be upgraded, unless OUTCOME_ENABLE_LEGACY_SUPPORT_FOR is set to 210 or lower.
      • Concepts now live in OUTCOME_V2_NAMESPACE::concepts namespace. Previously concepts lived in the convert namespace, now they live in their own namespace.
      • New concepts basic_result<T> and basic_outcome<T> added. End users were finding an unhelpful gap in between is_basic_result<T> and value_or_error<T> where they wanted a concept that matched types which were basic_result, but not exactly one of those. Concepts filling that gap were added.
      • Operation TRY works differently from Outcome v2.2 onwards. This is a severely code breaking change which change the syntax of how one uses OUTCOME_TRY(). A regular expression suitable for upgrading code can be found in the list of changes between Outcome v2.1 and v2.2.
    • Bug fixes:
      • #224 The clang Apple ships in Xcode 11.4 (currently the latest) has not been patched with the fixes to LLVM clang that fix noexcept(std::is_constructible<T, void>) failing to compile which I originally submitted years ago. So give up waiting on Apple to fix their clang, add a workaround to Outcome.
      • Spare storage could not be used from within no-value policy classes. Due to an obvious brain fart when writing the code at the time, the spare storage APIs had the wrong prototype which prevented them working from within policy classes. Sorry.
  • PolyCollection:
    • Fixed internal ambiguity problem between boost::type_erasure::any and boost::any (issue #17).
    • Maintenance work.
  • Polygon:
    • C++20 fixed for event_comparison_type, vertex_equality_predicate_type, and voronoi_predicates. (Glen Fernandes)
  • SmartPtr:
    • Added owner_equals to shared_ptr, weak_ptr, local_shared_ptr.
    • Added owner_hash_value to shared_ptr, weak_ptr.
    • Added owner_equal_to, owner_hash.
    • Added std::hash specializations for shared_ptr, local_shared_ptr.
    • Added boost::hash support to, and std::hash, std::equal_to specializations for, weak_ptr.
  • Stacktrace:
    • Fixed a build error when compiled with -fno-exceptions (thanks to Jeremiah Rodriguez #91).
  • System:
    • operator bool() now returns failed() instead of value() != 0.
  • Type_Traits:
    • Implemented conjunction, disjunction, negation, is_trivially_copyable, is_scoped_enum, and is_unscoped_enum. (Glen Fernandes)
  • Variant:
    • Fixed warnings on missing override (thanks to EugeneZelenko #78).
    • Fixes for the the Embarcadero compilers (thanks to Edward Diener #79).
    • Updated header locations to avoid warnings about using deprecated headers (thanks to Andrey Semashev #80)
  • Variant2:
    • Added support for derived types in visit.
    • Improved compilation performance for many (hundreds of) alternatives.
    • Added support for visit<R>.
  • Wave:
    • Implement C++20 features for variadics, including __VA_OPT__ (PR#75)
    • Implement __has_include (PR#102)
    • Introduce new sample: check_macro_naming, useful with Boost itself (PR#97)
    • Fix compilation issue caused by std::allocator member removal in C++20 (PR#72)
    • Repair Xpressive lexer and token_statistics sample (PR#79)
    • Repair lexertl lexer (PR#78)
    • Ensure hooks are run on predefined macros as well (PR#87)
    • Various minor bug fixes
    • C++98/03 support is now deprecated and will be removed in 1.77
  • YAP:
    • Fixed compilation errors for placeholders; they now work in the general case, and in particular work with yap::print().
    • constexpr all the YAP.
    • Fix printing of correct value category in yap::print().
    • Doc clarification.
  • TODO

Updated Tools

  • Boostbook:
    • Change encoding of generated documentation from US-ASCII to UTF-8. (Glen Fernandes)

Compilers Tested

Boost's primary test compilers are:

  • TODO

Boost's additional test compilers include:

  • TODO