Clang 7.0.0 (In-Progress) Release Notes

Written by the LLVM Team


These are in-progress notes for the upcoming Clang 7 release. Release notes for previous releases can be found on the Download Page.


This document contains the release notes for the Clang C/C++/Objective-C frontend, part of the LLVM Compiler Infrastructure, release 7.0.0. Here we describe the status of Clang 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 Clang or LLVM, including information about the latest release, please see the Clang Web Site or the LLVM Web Site.

Note that if you are reading this file from a Subversion checkout or the main Clang 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 Clang 7.0.0?

Some of the major new features and improvements to Clang are listed here. Generic improvements to Clang as a whole or to its underlying infrastructure are described first, followed by language-specific sections with improvements to Clang’s support for those languages.

Major New Features

Improvements to Clang’s diagnostics

  • -Wc++98-compat-extra-semi is a new flag, which was previously inseparable from -Wc++98-compat-pedantic. The latter still controls the new flag.
  • -Wextra-semi now also controls -Wc++98-compat-extra-semi. Please do note that if you pass -Wno-c++98-compat-pedantic, it implies -Wno-c++98-compat-extra-semi, so if you want that diagnostic, you need to explicitly re-enable it (e.g. by appending -Wextra-semi).

Deprecated Compiler Flags

The following options are deprecated and ignored. They will be removed in future versions of Clang.

Modified Compiler Flags

  • Before Clang 7.0, we prepended the # character to the –autocomplete argument to enable cc1 flags. For example, when the -cc1 or -Xclang flag is in the clang invocation, the shell executed clang –autocomplete=#-<flag to be completed>. Clang 7.0 now requires the whole invocation including all flags to be passed to the –autocomplete like this: clang –autocomplete=-cc1,-xc++,-fsyn.

New Pragmas in Clang

Clang now supports the …

Attribute Changes in Clang

  • Clang now supports function multiversioning with attribute ‘target’ on ELF based x86/x86-64 environments by using indirect functions. This implementation has a few minor limitations over the GCC implementation for the sake of AST sanity, however it is otherwise compatible with existing code using this feature for GCC. Consult the documentation for the target attribute for more information.

Windows Support

Clang’s support for building native Windows programs …

C Language Changes in Clang

C11 Feature Support

C++ Language Changes in Clang

C++1z Feature Support

Internal API Changes

These are major API changes that have happened since the 6.0.0 release of Clang. If upgrading an external codebase that uses Clang as a library, this section should help get you past the largest hurdles of upgrading.

New Issues Found

Python Binding Changes

The following methods have been added:

Additional Information

A wide variety of additional information is available on the Clang web page. The web page contains versions of the API documentation which are up-to-date with the Subversion version of the source code. You can access versions of these documents specific to this release by going into the “clang/docs/” directory in the Clang tree.

If you have any questions or comments about Clang, please feel free to contact us via the mailing list.