Clang 3.5 (In-Progress) Release Notes¶
- What’s New in Clang 3.5?
- Core Analysis Improvements
- New Issues Found
- Significant Known Problems
- Additional Information
Written by the LLVM Team
These are in-progress notes for the upcoming Clang 3.5 release. You may prefer the Clang 3.4 Release Notes.
This document contains the release notes for the Clang C/C++/Objective-C frontend, part of the LLVM Compiler Infrastructure, release 3.5. 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.
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.
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.
- Clang uses the new MingW ABI GCC 4.7 changed the mingw ABI. Clang 3.4 and older use the GCC 4.6 ABI. Clang 3.5 and newer use the GCC 4.7 abi.
- The __has_attribute feature test is now target-aware. Older versions of Clang would return true when the attribute spelling was known, regardless of whether the attribute was available to the specific target. Clang now returns true only when the attribute pertains to the current compilation target.
Improvements to Clang’s diagnostics¶
Clang’s diagnostics are constantly being improved to catch more issues, explain them more clearly, and provide more accurate source information about them. The improvements since the 3.4 release include:
The integrated assembler is now turned on by default on ARM (and Thumb), so the use of the option -fintegrated-as is now redundant on those architectures. This is an important move to both eat our own dog food and to ease cross-compilation tremendously.
We are aware of the problems that this may cause for code bases that rely on specific GNU syntax or extensions, and we’re working towards getting them all fixed. Please, report bugs or feature requests if you find anything. In the meantime, use -fno-integrated-as to revert back the call to GNU assembler.
In order to provide better diagnostics, the integrated assembler validates inline assembly when the integrated assembler is enabled. Because this is considered a feature of the compiler, it is controlled via the fintegrated-as and fno-integrated-as flags which enable and disable the integrated assembler respectively. -integrated-as and -no-integrated-as are now considered legacy flags (but are available as an alias to prevent breaking existing users), and users are encouraged to switch to the equivalent new feature flag.
These are major API changes that have happened since the 3.4 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.
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.