docs/ReleaseNotes.rst - clang - Git at Google

 =====================================
 Clang 3.5 (In-Progress) Release Notes
 =====================================

 .. contents::
    :local:
    :depth: 2

 Written by the `LLVM Team <http://llvm.org/>`_

 .. warning::

    These are in-progress notes for the upcoming Clang 3.5 release. You may
    prefer the `Clang 3.4 Release Notes
    <http://llvm.org/releases/3.4/tools/clang/docs/ReleaseNotes.html>`_.

 Introduction
 ============

 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 <http://llvm.org/docs/ReleaseNotes.html>`_. All LLVM
 releases may be downloaded from the `LLVM releases web
 site <http://llvm.org/releases/>`_.

 For more information about Clang or LLVM, including information about
 the latest release, please check out the main please see the `Clang Web
 Site <http://clang.llvm.org>`_ or the `LLVM Web
 Site <http://llvm.org>`_.

 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 <http://llvm.org/releases/>`_.

 What's New in Clang 3.5?
 ========================

 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
 ------------------

 - 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:

 - GCC compatibility: Clang displays a warning on unsupported gcc
   optimization flags instead of an error.

 -  ...

 New Compiler Flags
 ------------------

 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.

 Deprecated flags `-faddress-sanitizer`, `-fthread-sanitizer`,
 `-fcatch-undefined-behavior` and `-fbounds-checking` were removed in favor of
 `-fsanitize=` family of flags.

 It is now possible to get optimization reports from the major transformation
 passes via three new flags: `-Rpass`, `-Rpass-missed` and `-Rpass-analysis`.
 These flags take a POSIX regular expression which indicates the name
 of the pass (or passes) that should emit optimization remarks.

 The option `-u` is forwarded to the linker on gnutools toolchains.

 New Pragmas in Clang
 -----------------------

 Loop optimization hints can be specified using the new `#pragma clang loop`
 directive just prior to the desired loop. The directive allows vectorization,
 interleaving, and unrolling to be enabled or disabled. Vector width as well
 as interleave and unrolling count can be manually specified.  See language
 extensions for details.

 Clang now supports the `#pragma unroll` directive to specify loop unrolling
 optimization hints.  Placed just prior to the desired loop, `#pragma unroll`
 directs the loop unroller to attempt to fully unroll the loop.  The pragma may
 also be specified with a positive integer parameter indicating the desired
 unroll count: `#pragma unroll _value_`.  The unroll count parameter can be
 optionally enclosed in parentheses.

 C Language Changes in Clang
 ---------------------------

 ...

 C11 Feature Support
 ^^^^^^^^^^^^^^^^^^^

 ...

 C++ Language Changes in Clang
 -----------------------------

 - ...

 C++11 Feature Support
 ^^^^^^^^^^^^^^^^^^^^^

 ...

 Objective-C Language Changes in Clang
 -------------------------------------

 ...

 OpenCL C Language Changes in Clang
 ----------------------------------

 ...

 Internal API Changes
 --------------------

 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.

 ...

 libclang
 --------

 ...

 Static Analyzer
 ---------------

 The `-analyzer-config` options are now passed from scan-build through to
 ccc-analyzer and then to Clang.

 With the option `-analyzer-config stable-report-filename=true`,
 instead of `report-XXXXXX.html`, scan-build/clang analyzer generate
 `report-<filename>-<function, method name>-<function position>-<id>.html`.
 (id = i++ for several issues found in the same function/method).

 List the function/method name in the index page of scan-build.

 ...

 Core Analysis Improvements
 ==========================

 - ...

 New Issues Found
 ================

 - ...

 Python Binding Changes
 ----------------------

 The following methods have been added:

 -  ...

 Significant Known Problems
 ==========================

 Additional Information
 ======================

 A wide variety of additional information is available on the `Clang web
 page <http://clang.llvm.org/>`_. 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 <http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev>`_.
	=====================================
	Clang 3.5 (In-Progress) Release Notes
	=====================================

	.. contents::
	:local:
	:depth: 2

	Written by the `LLVM Team <http://llvm.org/>`_

	.. warning::

	These are in-progress notes for the upcoming Clang 3.5 release. You may
	prefer the `Clang 3.4 Release Notes
	<http://llvm.org/releases/3.4/tools/clang/docs/ReleaseNotes.html>`_.

	Introduction
	============

	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 <http://llvm.org/docs/ReleaseNotes.html>`_. All LLVM
	releases may be downloaded from the `LLVM releases web
	site <http://llvm.org/releases/>`_.

	For more information about Clang or LLVM, including information about
	the latest release, please check out the main please see the `Clang Web
	Site <http://clang.llvm.org>`_ or the `LLVM Web
	Site <http://llvm.org>`_.

	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 <http://llvm.org/releases/>`_.

	What's New in Clang 3.5?
	========================

	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
	------------------

	- 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:

	- GCC compatibility: Clang displays a warning on unsupported gcc
	optimization flags instead of an error.

	- ...

	New Compiler Flags
	------------------

	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.

	Deprecated flags `-faddress-sanitizer`, `-fthread-sanitizer`,
	`-fcatch-undefined-behavior` and `-fbounds-checking` were removed in favor of
	`-fsanitize=` family of flags.

	It is now possible to get optimization reports from the major transformation
	passes via three new flags: `-Rpass`, `-Rpass-missed` and `-Rpass-analysis`.
	These flags take a POSIX regular expression which indicates the name
	of the pass (or passes) that should emit optimization remarks.

	The option `-u` is forwarded to the linker on gnutools toolchains.

	New Pragmas in Clang
	-----------------------

	Loop optimization hints can be specified using the new `#pragma clang loop`
	directive just prior to the desired loop. The directive allows vectorization,
	interleaving, and unrolling to be enabled or disabled. Vector width as well
	as interleave and unrolling count can be manually specified. See language
	extensions for details.

	Clang now supports the `#pragma unroll` directive to specify loop unrolling
	optimization hints. Placed just prior to the desired loop, `#pragma unroll`
	directs the loop unroller to attempt to fully unroll the loop. The pragma may
	also be specified with a positive integer parameter indicating the desired
	unroll count: `#pragma unroll _value_`. The unroll count parameter can be
	optionally enclosed in parentheses.

	C Language Changes in Clang
	---------------------------

	...

	C11 Feature Support
	^^^^^^^^^^^^^^^^^^^

	...

	C++ Language Changes in Clang
	-----------------------------

	- ...

	C++11 Feature Support
	^^^^^^^^^^^^^^^^^^^^^

	...

	Objective-C Language Changes in Clang
	-------------------------------------

	...

	OpenCL C Language Changes in Clang
	----------------------------------

	...

	Internal API Changes
	--------------------

	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.

	...

	libclang
	--------

	...

	Static Analyzer
	---------------

	The `-analyzer-config` options are now passed from scan-build through to
	ccc-analyzer and then to Clang.

	With the option `-analyzer-config stable-report-filename=true`,
	instead of `report-XXXXXX.html`, scan-build/clang analyzer generate
	`report-<filename>-<function, method name>-<function position>-<id>.html`.
	(id = i++ for several issues found in the same function/method).

	List the function/method name in the index page of scan-build.

	...

	Core Analysis Improvements
	==========================

	- ...

	New Issues Found
	================

	- ...

	Python Binding Changes
	----------------------

	The following methods have been added:

	- ...

	Significant Known Problems
	==========================

	Additional Information
	======================

	A wide variety of additional information is available on the `Clang web
	page <http://clang.llvm.org/>`_. 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 <http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev>`_.