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Diffstat (limited to 'libcxx/docs/ReleaseNotes.rst')
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1 files changed, 4 insertions, 125 deletions
diff --git a/libcxx/docs/ReleaseNotes.rst b/libcxx/docs/ReleaseNotes.rst index 060ab387fe5f..88a4859e093b 100644 --- a/libcxx/docs/ReleaseNotes.rst +++ b/libcxx/docs/ReleaseNotes.rst @@ -1,5 +1,5 @@ ========================================= -Libc++ 16.0.0 (In-Progress) Release Notes +Libc++ 17.0.0 (In-Progress) Release Notes ========================================= .. contents:: @@ -10,7 +10,7 @@ Written by the `Libc++ Team <https://libcxx.llvm.org>`_ .. warning:: - These are in-progress notes for the upcoming libc++ 16 release. + These are in-progress notes for the upcoming libc++ 17 release. Release notes for previous releases can be found on `the Download Page <https://releases.llvm.org/download.html>`_. @@ -18,7 +18,7 @@ Introduction ============ This document contains the release notes for the libc++ C++ Standard Library, -part of the LLVM Compiler Infrastructure, release 16.0.0. Here we describe the +part of the LLVM Compiler Infrastructure, release 17.0.0. Here we describe the status of libc++ in some detail, including major improvements from the previous release and new feature work. For the general LLVM release notes, see `the LLVM documentation <https://llvm.org/docs/ReleaseNotes.html>`_. All LLVM releases may @@ -32,113 +32,20 @@ main Libc++ web page, this document applies to the *next* release, not the current one. To see the release notes for a specific release, please see the `releases page <https://llvm.org/releases/>`_. -What's New in Libc++ 16.0.0? +What's New in Libc++ 17.0.0? ============================ -The main focus of the libc++ team has been to implement new C++20 and C++23 -features. - -The C++20 format library has improved but it not yet considered stable. The -main improvements are additional formatters for the chrono calendar types. Work -on formatting ranges has started. - -The C++20 ranges library has been completed and is no longer experimental. Some -``views`` have not been implemented yet. Work on C++23 ranges has started. - -The C++20 spaceship operator has been added to more types, the work is still -ongoing. - Implemented Papers ------------------ -- P2499R0 - ``string_view`` range constructor should be ``explicit`` -- P2417R2 - A more constexpr bitset -- P2445R1 - ``std::forward_like`` -- P2273R3 - Making ``std::unique_ptr`` constexpr -- P0591R4 - Utility functions to implement uses-allocator construction -- P2291R3 - Add Constexpr Modifiers to Functions ``to_chars`` and - ``from_chars`` for Integral Types in ``<charconv>`` Header -- P0220R1 - Adopt Library Fundamentals V1 TS Components for C++17 -- P0482R6 - char8_t: A type for UTF-8 characters and strings -- P2438R2 - ``std::string::substr() &&`` -- P0600R1 - ``nodiscard`` in the library -- P0339R6 - ``polymorphic_allocator<>`` as a vocabulary type -- P1169R4 - ``static operator()`` -- P0415R1 - ``constexpr`` for ``std::complex`` -- P1208R6 - ``std::source_location`` -- P0323R12 - ``std::expected`` -- P1035R7 - Input Range Adaptors -- P2325R3 - Views should not be required to be default constructible -- P2446R2 - ``views::as_rvalue`` -- P1020R1 - Smart pointer creation with default initialization -- P2210R2 - Superior String Splitting -- P2286R8 - Formatting Ranges Improvements and New Features ----------------------------- -- Declarations of ``std::c8rtomb()`` and ``std::mbrtoc8()`` from P0482R6 are - now provided when implementations in the global namespace are provided by - the C library. -- Implemented ``<memory_resource>`` header from C++17 -- `D122780 <https://reviews.llvm.org/D122780>`_ Improved the performance of std::sort -- The ``ranges`` versions of ``copy``, ``move``, ``copy_backward`` and ``move_backward`` are now also optimized for - ``std::deque<>::iterator``, which can lead to up to 20x performance improvements on certain algorithms. -- The ``std`` and ``ranges`` versions of ``copy``, ``move``, ``copy_backward`` and ``move_backward`` are now also - optimized for ``join_view::iterator``, which can lead to up to 20x performance improvements on certain combinations of - iterators and algorithms. Deprecations and Removals ------------------------- -- ``unary_function`` and ``binary_function`` are no longer provided in C++17 and newer Standard modes. - They can be re-enabled with ``_LIBCPP_ENABLE_CXX17_REMOVED_UNARY_BINARY_FUNCTION``. - -- Several incidental transitive includes have been removed from libc++. Those - includes are removed based on the language version used. Incidental transitive - inclusions of the following headers have been removed: - - - C++11, C++14, C++17, and C++20: ``chrono`` - - C++2b: ``algorithm``, ``array``, ``atomic``, ``bit``, ``chrono``, - ``climits``, ``cmath``, ``compare``, ``concepts``, ``cstdarg``, ``cstddef``, - ``cstdint``, ``cstdlib``, ``cstring``, ``ctime``, ``exception``, - ``functional``, ``initializer_list``, ``iosfwd``, ``iterator``, ``limits``, - ``memory``, ``new``, ``numeric``, ``optional``, ``ratio``, ``stdexcept``, - ``string``, ``tuple``, ``type_traits``, ``typeinfo``, ``unordered_map``, - ``utility``, ``variant``, ``vector``. - - Users can also remove all incidental transitive includes by defining - ``_LIBCPP_REMOVE_TRANSITIVE_INCLUDES`` regardless of the language version - in use. Note that in the future, libc++ reserves the right to remove - incidental transitive includes more aggressively, in particular regardless - of the language version in use. - -- The legacy testing system for libc++, libc++abi, and libunwind has been removed. - All known clients have been migrated to the new configuration system, but please - reach out to the libc++ developers if you find something missing in the new - configuration system. - -- The functions ``to_chars`` and ``from_chars`` for integral types are - available starting with C++17. Libc++ offered these functions in C++11 and - C++14 as an undocumented extension. This extension makes it hard to implement - the C++23 paper that makes these functions ``constexpr``, therefore the - extension has been removed. - -- The ``_LIBCPP_ENABLE_CXX03_FUNCTION`` macro that allowed re-enabling the now-deprecated C++03 implementation of - ``std::function`` has been removed. Users who need to use ``std::function`` should switch to C++11 and above. - -- The contents of ``<experimental/memory_resource>`` are now deprecated since libc++ ships ``<memory_resource>`` now. - Please migrate to ``<memory_resource>`` instead. Per libc++'s TS deprecation policy, - ``<experimental/memory_resource>`` will be removed in LLVM 18. - -- The ``_LIBCPP_DEBUG`` macro is not honored anymore, and it is an error to try to use it. Please migrate to - ``_LIBCPP_ENABLE_DEBUG_MODE`` instead. Upcoming Deprecations and Removals ---------------------------------- -- The base template for ``std::char_traits`` has been marked as deprecated and will be removed in LLVM 18. If - you are using ``std::char_traits`` with types other than ``char``, ``wchar_t``, ``char8_t``, ``char16_t``, - ``char32_t`` or a custom character type for which you specialized ``std::char_traits``, your code will stop - working when we remove the base template. The Standard does not mandate that a base template is provided, - and such a base template is bound to be incorrect for some types, which could currently cause unexpected - behavior while going undetected. - The ``_LIBCPP_AVAILABILITY_CUSTOM_VERBOSE_ABORT_PROVIDED`` macro will not be honored anymore in LLVM 18. Please see the updated documentation about the safe libc++ mode and in particular the ``_LIBCPP_VERBOSE_ABORT`` @@ -146,37 +53,9 @@ Upcoming Deprecations and Removals API Changes ----------- -- The comparison operators on ``thread::id`` are now defined as free-standing - functions instead of as hidden friends, in conformance with the C++ standard. - Also see `issue 56187 <https://github.com/llvm/llvm-project/issues/56187>`_. - -- ``_LIBCPP_ENABLE_NODISCARD`` and ``_LIBCPP_DISABLE_NODISCARD_AFTER_CXX17`` are no longer respected. - Any standards-required ``[[nodiscard]]`` applications in C++20 are now always enabled. Any extended applications - are now enabled by default and can be disabled by defining ``_LIBCPP_DISABLE_NODISCARD_EXT``. - -- ``_LIBCPP_VERSION`` was previously defined to e.g. ``15001`` to represent LLVM 15.0.01, but this value had been - left undocumented. Starting with LLVM 16, ``_LIBCPP_VERSION`` will contain the version of LLVM represented as - ``XXYYZZ``. In other words, ``_LIBCPP_VERSION`` is gaining a digit. This should not be an issue for existing - code, since using e.g. ``_LIBCPP_VERSION > 15000`` will still give the right answer now that ``_LIBCPP_VERSION`` - is defined as e.g. ``160000`` (with one more digit). ABI Affecting Changes --------------------- -- In freestanding mode, ``atomic<small enum class>`` does not contain a lock byte anymore if the platform - can implement lockfree atomics for that size. More specifically, in LLVM <= 11.0.1, an ``atomic<small enum class>`` - would not contain a lock byte. This was broken in LLVM >= 12.0.0, where it started including a lock byte despite - the platform supporting lockfree atomics for that size. Starting in LLVM 15.0.1, the ABI for these types has been - restored to what it used to be (no lock byte), which is the most efficient implementation. - - This ABI break only affects users that compile with ``-ffreestanding``, and only for ``atomic<T>`` where ``T`` - is a non-builtin type that could be lockfree on the platform. See https://llvm.org/D133377 for more details. - -- When building libc++ against newlib/picolibc, the type of ``regex_type_traits::char_class_type`` was changed to - ``uint16_t`` since all values of ``ctype_base::mask`` are taken. This is technically an ABI break, but including - ``<regex> `` has triggered a ``static_assert`` failure since libc++ 14, so it is unlikely that this causes - problems for existing users. Build System Changes -------------------- -- Support for ``libcxx``, ``libcxxabi`` and ``libunwind`` in ``LLVM_ENABLE_PROJECTS`` has officially - been removed. Instead, please build according to :ref:`these instructions <build instructions>`. |