49e7be2e5b
This patch gets rid of technical debt around std::pointer_safety which, I claim, is entirely unnecessary. I don't think anybody has used std::pointer_safety in actual code because we do not implement the underlying garbage collection support. In fact, P2186 even proposes removing these facilities entirely from a future C++ version. As such, I think it's entirely fine to get rid of complex workarounds whose goals were to avoid breaking the ABI back in 2017. I'm putting this up both to get reviews and to discuss this proposal for a breaking change. I think we should be comfortable with making these tiny breaks if we are confident they won't hurt anyone, which I'm fairly confident is the case here. Differential Revision: https://reviews.llvm.org/D100410
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=========================================
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Libc++ 13.0.0 (In-Progress) Release Notes
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=========================================
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.. contents::
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:local:
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:depth: 2
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Written by the `Libc++ Team <https://libcxx.llvm.org>`_
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.. warning::
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These are in-progress notes for the upcoming libc++ 13 release.
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Release notes for previous releases can be found on
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`the Download Page <https://releases.llvm.org/download.html>`_.
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Introduction
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============
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This document contains the release notes for the libc++ C++ Standard Library,
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part of the LLVM Compiler Infrastructure, release 13.0.0. Here we describe the
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status of libc++ in some detail, including major improvements from the previous
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release and new feature work. For the general LLVM release notes, see `the LLVM
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documentation <https://llvm.org/docs/ReleaseNotes.html>`_. All LLVM releases may
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be downloaded from the `LLVM releases web site <https://llvm.org/releases/>`_.
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For more information about libc++, please see the `Libc++ Web Site
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<https://libcxx.llvm.org>`_ or the `LLVM Web Site <https://llvm.org>`_.
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Note that if you are reading this file from a Git checkout or the
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main Libc++ web page, this document applies to the *next* release, not
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the current one. To see the release notes for a specific release, please
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see the `releases page <https://llvm.org/releases/>`_.
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What's New in Libc++ 13.0.0?
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============================
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New Features
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------------
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- ...
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API Changes
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-----------
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- There has been several changes in the tuple constructors provided by libc++.
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Those changes were made as part of an effort to regularize libc++'s tuple
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implementation, which contained several subtle bugs due to these extensions.
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If you notice a build breakage when initializing a tuple, make sure you
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properly initialize all the tuple elements - this is probably the culprit.
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In particular, the extension allowing tuples to be constructed from fewer
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elements than the number of elements in the tuple (in which case the remaining
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elements would be default-constructed) has been removed. See https://godbolt.org/z/sqozjd.
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Also, the extension allowing a tuple to be constructed from an array has been
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removed. See https://godbolt.org/z/5esqbW.
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- The ``std::pointer_safety`` utility and related functions are not available
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in C++03 anymore. Furthermore, in other standard modes, it has changed from
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a struct to a scoped enumeration, which is an ABI break. Finally, the
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``std::get_pointer_safety`` function was previously in the dylib, but it
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is now defined as inline in the headers.
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While this is technically both an API and an ABI break, we do not expect
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``std::pointer_safety`` to have been used at all in real code, since we
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never implemented the underlying support for garbage collection.
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