1 ======================================== 2 Libc++ 8.0.0 (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++ 8 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 8.0.0. 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 Subversion 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++ 8.0.0? 36 =========================== 37 38 New Features 39 ------------ 40 41 API Changes 42 ----------- 43 - Building libc++ for Mac OSX 10.6 is not supported anymore. 44 - Starting with LLVM 8.0.0, users that wish to link together translation units 45 built with different versions of libc++'s headers into the same final linked 46 image MUST define the _LIBCPP_HIDE_FROM_ABI_PER_TU macro to 1 when building 47 those translation units. Not defining _LIBCPP_HIDE_FROM_ABI_PER_TU to 1 and 48 linking translation units built with different versions of libc++'s headers 49 together may lead to ODR violations and ABI issues. On the flipside, code 50 size improvements should be expected for everyone not defining the macro. 51 - Starting with LLVM 8.0.0, std::dynarray has been removed from the library. 52 std::dynarray was a feature proposed for C++14 that was pulled from the 53 Standard at the last minute and was never standardized. Since there are no 54 plans to standardize this facility it is being removed. 55 - Starting with LLVM 8.0.0, std::bad_array_length has been removed from the 56 library. std::bad_array_length was a feature proposed for C++14 alongside 57 std::dynarray, but it never actually made it into the C++ Standard. There 58 are no plans to standardize this feature at this time. Formally speaking, 59 this removal constitutes an ABI break because the symbols were shipped in 60 the shared library. However, on macOS systems, the feature was not usable 61 because it was hidden behind availability annotations. We do not expect 62 any actual breakage to happen from this change. 63
