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      1 =========================================
      2 Libc++ 13.0.0 (In-Progress) Release Notes
      3 =========================================
      4 
      5 .. contents::
      6    :local:
      7    :depth: 2
      8 
      9 Written by the `Libc++ Team <https://libcxx.llvm.org>`_
     10 
     11 .. warning::
     12 
     13    These are in-progress notes for the upcoming libc++ 13 release.
     14    Release notes for previous releases can be found on
     15    `the Download Page <https://releases.llvm.org/download.html>`_.
     16 
     17 Introduction
     18 ============
     19 
     20 This document contains the release notes for the libc++ C++ Standard Library,
     21 part of the LLVM Compiler Infrastructure, release 13.0.0. Here we describe the
     22 status of libc++ in some detail, including major improvements from the previous
     23 release and new feature work. For the general LLVM release notes, see `the LLVM
     24 documentation <https://llvm.org/docs/ReleaseNotes.html>`_. All LLVM releases may
     25 be downloaded from the `LLVM releases web site <https://llvm.org/releases/>`_.
     26 
     27 For more information about libc++, please see the `Libc++ Web Site
     28 <https://libcxx.llvm.org>`_ or the `LLVM Web Site <https://llvm.org>`_.
     29 
     30 Note that if you are reading this file from a Git checkout or the
     31 main Libc++ web page, this document applies to the *next* release, not
     32 the current one. To see the release notes for a specific release, please
     33 see the `releases page <https://llvm.org/releases/>`_.
     34 
     35 What's New in Libc++ 13.0.0?
     36 ============================
     37 
     38 New Features
     39 ------------
     40 
     41 - ...
     42 
     43 API Changes
     44 -----------
     45 
     46 - There has been several changes in the tuple constructors provided by libc++.
     47   Those changes were made as part of an effort to regularize libc++'s tuple
     48   implementation, which contained several subtle bugs due to these extensions.
     49   If you notice a build breakage when initializing a tuple, make sure you
     50   properly initialize all the tuple elements - this is probably the culprit.
     51 
     52   In particular, the extension allowing tuples to be constructed from fewer
     53   elements than the number of elements in the tuple (in which case the remaining
     54   elements would be default-constructed) has been removed. See https://godbolt.org/z/sqozjd.
     55 
     56   Also, the extension allowing a tuple to be constructed from an array has been
     57   removed. See https://godbolt.org/z/5esqbW.
     58 
     59 - The ``std::pointer_safety`` utility and related functions are not available
     60   in C++03 anymore. Furthermore, in other standard modes, it has changed from
     61   a struct to a scoped enumeration, which is an ABI break. Finally, the
     62   ``std::get_pointer_safety`` function was previously in the dylib, but it
     63   is now defined as inline in the headers.
     64 
     65   While this is technically both an API and an ABI break, we do not expect
     66   ``std::pointer_safety`` to have been used at all in real code, since we
     67   never implemented the underlying support for garbage collection.
     68