Libc++ 14.0.0 (In-Progress) Release Notes

Written by the Libc++ Team


These are in-progress notes for the upcoming libc++ 14 release. Release notes for previous releases can be found on the Download Page.


This document contains the release notes for the libc++ C++ Standard Library, part of the LLVM Compiler Infrastructure, release 14.0.0. 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. All LLVM releases may be downloaded from the LLVM releases web site.

For more information about libc++, please see the Libc++ Web Site or the LLVM Web Site.

Note that if you are reading this file from a Git checkout or the 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.

What’s New in Libc++ 14.0.0?

New Features

  • There’s initial support for the C++20 header <format>. The implementation is incomplete. Some functions are known to be inefficient; both in memory usage and performance. The implementation is considered experimental and isn’t considered ABI stable.
  • There’s a new CMake option LIBCXX_ENABLE_UNICODE to disable Unicode support in the <format> header. This only affects the estimation of the output width of the format functions.