[llvm-branch-commits] [libcxx] 2df1cec - [libc++][doc] Update the release notes for LLVM 19. (#99061)
Tobias Hieta via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Fri Jul 26 00:20:15 PDT 2024
Author: Mark de Wever
Date: 2024-07-26T09:20:03+02:00
New Revision: 2df1cec9db73697a04e733de39ab9ac63c7b2d9b
URL: https://github.com/llvm/llvm-project/commit/2df1cec9db73697a04e733de39ab9ac63c7b2d9b
DIFF: https://github.com/llvm/llvm-project/commit/2df1cec9db73697a04e733de39ab9ac63c7b2d9b.diff
LOG: [libc++][doc] Update the release notes for LLVM 19. (#99061)
This is a preparation for the upcoming LLVM 19 release.
Added:
Modified:
libcxx/docs/ReleaseNotes/19.rst
libcxx/docs/ReleaseNotes/20.rst
libcxx/docs/Status/SpecialMath.rst
Removed:
################################################################################
diff --git a/libcxx/docs/ReleaseNotes/19.rst b/libcxx/docs/ReleaseNotes/19.rst
index 439f552db59a8..c2c2bfbed4ac3 100644
--- a/libcxx/docs/ReleaseNotes/19.rst
+++ b/libcxx/docs/ReleaseNotes/19.rst
@@ -35,6 +35,20 @@ see the `releases page <https://llvm.org/releases/>`_.
What's New in Libc++ 19.0.0?
==============================
+The main focus of the libc++ team has been to implement new C++20, C++23,
+and C++26 features.
+
+Experimental support for the time zone database has progressed.
+
+Work on the ranges support has progressed. See
+:ref:`ranges-status` for the current status.
+
+Work on the experimental C++17 Parallel STL has progressed. See
+:ref:`pstl-status` for the current status.
+
+Work on the C++17 mathematical special functions has started. See
+:ref:`special-math-status` for the current status.
+
Implemented Papers
------------------
@@ -59,14 +73,21 @@ Implemented Papers
- P0019R8 - ``std::atomic_ref``
- P2389R2 - Alias template ``dims`` for the ``extents`` of ``mdspan``
- P1223R5 - ``ranges::find_last()``, ``ranges::find_last_if()``, and ``ranges::find_last_if_not()``
+- P2602R2 - Poison Pills are Too Toxic
+- P1981R0 - Rename ``leap`` to ``leap_second``
+- P1982R0 - Rename ``link`` to ``time_zone_link``
+
Improvements and New Features
-----------------------------
- The performance of growing ``std::vector`` has been improved for trivially relocatable types.
-- A lot of types are considered trivially relocatable now, including ``vector`` and ``string``.
-- The performance of ``ranges::fill`` and ``ranges::fill_n`` has been improved for ``vector<bool>::iterator``\s,
+
+- A lot of types are considered trivially relocatable now, including ``std::vector`` and ``std::string``.
+
+- The performance of ``std::ranges::fill`` and ``std::ranges::fill_n`` has been improved for ``std::vector<bool>::iterator``\s,
resulting in a performance increase of up to 1400x.
+
- The ``std::mismatch`` algorithm has been optimized for integral types, which can lead up to 40x performance
improvements.
@@ -74,7 +95,7 @@ Improvements and New Features
up to 100x.
- The ``std::set_intersection`` and ``std::ranges::set_intersection`` algorithms have been optimized to fast-forward over
- contiguous ranges of non-matching values, reducing the number of comparisons from linear to
+ contiguous ranges of non-matching values, reducing the number of comparisons from linear to
logarithmic growth with the number of elements in best-case scenarios.
- The ``_LIBCPP_ENABLE_CXX26_REMOVED_STRSTREAM`` macro has been added to make the declarations in ``<strstream>`` available.
@@ -101,15 +122,18 @@ Improvements and New Features
Note: bounded iterators currently are not supported for ``vector<bool>``.
+- In C++23 and C++26 the number of transitive includes in several headers has been reduced, improving the compilation speed.
+
+
Deprecations and Removals
-------------------------
-- The C++20 synchronization library (``<barrier>``, ``<latch>``, ``atomic::wait``, etc.) has been deprecated
+- The C++20 synchronization library (``<barrier>``, ``<latch>``, ``std::atomic::wait``, etc.) has been deprecated
in language modes prior to C++20. If you are using these features prior to C++20, please update to ``-std=c++20``.
In LLVM 20, the C++20 synchronization library will be removed entirely in language modes prior to C++20.
- ``_LIBCPP_DISABLE_NODISCARD_EXT`` has been removed. ``[[nodiscard]]`` applications are now unconditional.
- This decision is based on LEWGs discussion on `P3122 <https://wg21.link/P3122>` and `P3162 <https://wg21.link/P3162>`
+ This decision is based on LEWGs discussion on `P3122 <https://wg21.link/P3122>`_ and `P3162 <https://wg21.link/P3162>`_
to not use ``[[nodiscard]]`` in the standard.
- The ``LIBCXX_ENABLE_ASSERTIONS`` CMake variable that was used to enable the safe mode has been deprecated and setting
@@ -151,10 +175,11 @@ Deprecations and Removals
- libc++ no longer supports ``std::allocator<const T>`` and containers of ``const``-qualified element type, such
as ``std::vector<const T>`` and ``std::list<const T>``. This used to be supported as an undocumented extension.
If you were using ``std::vector<const T>``, replace it with ``std::vector<T>`` instead. The
- ``_LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST`` macro can be defined to temporarily re-enable this extension as
- folks transition their code. This macro will be honored for one released and ignored starting in LLVM 20.
+ ``_LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST`` macro can be defined
+ to temporarily re-enable this extension to make it easier to update user code.
+ This macro will be honored for one released and ignored starting in LLVM 20.
To assist with the clean-up process, consider running your code through Clang Tidy, with
- `std-allocator-const <https://clang.llvm.org/extra/clang-tidy/checks/portability/std-allocator-const.html>`
+ `std-allocator-const <https://clang.llvm.org/extra/clang-tidy/checks/portability/std-allocator-const.html>`_
enabled.
- When configuring libc++ with localization or threads disabled, the library no longer emits an error when
@@ -187,6 +212,9 @@ LLVM 20
``_LIBCPP_ENABLE_REMOVED_WEEKDAY_RELATIONAL_OPERATORS`` macro that was used to re-enable this extension will be
ignored in LLVM 20.
+- The ``_LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST`` macro will no longer have an effect.
+
+
LLVM 21
~~~~~~~
@@ -197,6 +225,7 @@ LLVM 21
If you are using C++03 in your project, you should consider moving to a newer version of the Standard to get the most out of libc++.
+
ABI Affecting Changes
---------------------
@@ -211,7 +240,7 @@ Build System Changes
- The ``LIBCXX_EXECUTOR`` and ``LIBCXXABI_EXECUTOR`` CMake variables have been removed. Please
set ``LIBCXX_TEST_PARAMS`` to ``executor=<...>`` instead.
-- The Cmake variable ``LIBCXX_ENABLE_CLANG_TIDY`` has been removed. The build system has been changed
+- The CMake variable ``LIBCXX_ENABLE_CLANG_TIDY`` has been removed. The build system has been changed
to automatically detect the presence of ``clang-tidy`` and the required ``Clang`` libraries.
- The CMake options ``LIBCXX_INSTALL_MODULES`` now defaults to ``ON``.
diff --git a/libcxx/docs/ReleaseNotes/20.rst b/libcxx/docs/ReleaseNotes/20.rst
index fb677b1667ddc..f959c8829277e 100644
--- a/libcxx/docs/ReleaseNotes/20.rst
+++ b/libcxx/docs/ReleaseNotes/20.rst
@@ -59,16 +59,28 @@ Deprecations and Removals
``_LIBCPP_ENABLE_REMOVED_WEEKDAY_RELATIONAL_OPERATORS`` macro that was used to re-enable this extension will be
ignored in LLVM 20.
+- TODO: The ``_LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST`` macro will no longer have an effect.
Upcoming Deprecations and Removals
----------------------------------
-LLVM 21
+LLVM 20
~~~~~~~
- TODO
+LLVM 21
+~~~~~~~
+
+- The status of the C++03 implementation will be frozen after the LLVM 21 release. This means that starting in LLVM 22, non-critical bug fixes may not be back-ported
+ to C++03, including LWG issues. C++03 is a legacy platform, where most projects are no longer actively maintained. To
+ reduce the amount of fixes required to keep such legacy projects compiling with up-to-date toolchains, libc++ will aim to freeze the status of the headers in C++03 mode to avoid unintended breaking changes.
+ See https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc for more details.
+
+ If you are using C++03 in your project, you should consider moving to a newer version of the Standard to get the most out of libc++.
+
+
ABI Affecting Changes
---------------------
diff --git a/libcxx/docs/Status/SpecialMath.rst b/libcxx/docs/Status/SpecialMath.rst
index fcc9f03e3ae64..46e5c97cdaab2 100644
--- a/libcxx/docs/Status/SpecialMath.rst
+++ b/libcxx/docs/Status/SpecialMath.rst
@@ -1,4 +1,4 @@
-.. special-math-status:
+.. _special-math-status:
======================================================
libc++ Mathematical Special Functions Status (P0226R1)
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