docs/ReleaseNotes.rst - clang - Git at Google

 =======================
 Clang 3.3 Release Notes
 =======================

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

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

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

 This document contains the release notes for the Clang C/C++/Objective-C
 frontend, part of the LLVM Compiler Infrastructure, release 3.3. 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 3.3?
 ========================

 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
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 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 3.2 release include:

 Extended Identifiers: Unicode Support and Universal Character Names
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 Clang 3.3 includes support for *extended identifiers* in C99 and C++.
 This feature allows identifiers to contain certain Unicode characters, as
 specified by the active language standard; these characters can be written
 directly in the source file using the UTF-8 encoding, or referred to using
 *universal character names* (``\u00E0``, ``\U000000E0``).

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

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

 - Clang now correctly implements language linkage for functions and variables.
   This means that, for example, it is now possible to overload static functions
   declared in an ``extern "C"`` context. For backwards compatibility, an alias
   with the unmangled name is still emitted if it is the only one and has the
   ``used`` attribute.

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

 These are major API changes that have happened since the 3.2 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.

 Value Casting
 ^^^^^^^^^^^^^

 Certain type hierarchies (TypeLoc, CFGElement, ProgramPoint, and SVal) were
 misusing the llvm::cast machinery to perform undefined operations. Their APIs
 have been changed to use two member function templates that return values
 instead of pointers or references - "T castAs" and "Optional<T> getAs" (in the
 case of the TypeLoc hierarchy the latter is "T getAs" and you can use the
 boolean testability of a TypeLoc (or its 'validity') to verify that the cast
 succeeded). Essentially all previous 'cast' usage should be replaced with
 'castAs' and 'dyn_cast' should be replaced with 'getAs'. See r175462 for the
 first example of such a change along with many examples of how code was
 migrated to the new API.

 Storage Class
 ^^^^^^^^^^^^^

 For each variable and function Clang used to keep the storage class as written
 in the source, the linkage and a semantic storage class. This was a bit
 redundant and the semantic storage class has been removed. The method
 getStorageClass now returns what is written in the source code for that decl.

 libclang
 --------

 The clang_CXCursorSet_contains() function previously incorrectly returned 0
 if it contained a CXCursor, contrary to what the documentation stated.  This
 has been fixed so that the function returns a non-zero value if the set
 contains a cursor.  This is API breaking change, but matches the intended
 original behavior.  Moreover, this also fixes the issue of an invalid CXCursorSet
 appearing to contain any CXCursor.

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

 The static analyzer (which contains additional code checking beyond compiler
 warnings) has improved significantly in both in the core analysis engine and
 also in the kinds of issues it can find.

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

 - Support for interprocedural reasoning about constructors and destructors.
 - New false positive suppression mechanisms that reduced the number of false
   null pointer dereference warnings due to interprocedural analysis.
 - Major performance enhancements to speed up interprocedural analysis

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

 - New memory error checks such as use-after-free with C++ 'delete'.
 - Detection of mismatched allocators and deallocators (e.g., using 'new' with
   'free()', 'malloc()' with 'delete').
 - Additional checks for misuses of Apple Foundation framework collection APIs.

 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 3.3 Release Notes
	=======================

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

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

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

	This document contains the release notes for the Clang C/C++/Objective-C
	frontend, part of the LLVM Compiler Infrastructure, release 3.3. 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 3.3?
	========================

	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
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

	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 3.2 release include:

	Extended Identifiers: Unicode Support and Universal Character Names
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

	Clang 3.3 includes support for extended identifiers in C99 and C++.
	This feature allows identifiers to contain certain Unicode characters, as
	specified by the active language standard; these characters can be written
	directly in the source file using the UTF-8 encoding, or referred to using
	universal character names (``\u00E0``, ``\U000000E0``).

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

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

	- Clang now correctly implements language linkage for functions and variables.
	This means that, for example, it is now possible to overload static functions
	declared in an ``extern "C"`` context. For backwards compatibility, an alias
	with the unmangled name is still emitted if it is the only one and has the
	``used`` attribute.

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

	These are major API changes that have happened since the 3.2 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.

	Value Casting
	^^^^^^^^^^^^^

	Certain type hierarchies (TypeLoc, CFGElement, ProgramPoint, and SVal) were
	misusing the llvm::cast machinery to perform undefined operations. Their APIs
	have been changed to use two member function templates that return values
	instead of pointers or references - "T castAs" and "Optional<T> getAs" (in the
	case of the TypeLoc hierarchy the latter is "T getAs" and you can use the
	boolean testability of a TypeLoc (or its 'validity') to verify that the cast
	succeeded). Essentially all previous 'cast' usage should be replaced with
	'castAs' and 'dyn_cast' should be replaced with 'getAs'. See r175462 for the
	first example of such a change along with many examples of how code was
	migrated to the new API.

	Storage Class
	^^^^^^^^^^^^^

	For each variable and function Clang used to keep the storage class as written
	in the source, the linkage and a semantic storage class. This was a bit
	redundant and the semantic storage class has been removed. The method
	getStorageClass now returns what is written in the source code for that decl.

	libclang
	--------

	The clang_CXCursorSet_contains() function previously incorrectly returned 0
	if it contained a CXCursor, contrary to what the documentation stated. This
	has been fixed so that the function returns a non-zero value if the set
	contains a cursor. This is API breaking change, but matches the intended
	original behavior. Moreover, this also fixes the issue of an invalid CXCursorSet
	appearing to contain any CXCursor.

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

	The static analyzer (which contains additional code checking beyond compiler
	warnings) has improved significantly in both in the core analysis engine and
	also in the kinds of issues it can find.

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

	- Support for interprocedural reasoning about constructors and destructors.
	- New false positive suppression mechanisms that reduced the number of false
	null pointer dereference warnings due to interprocedural analysis.
	- Major performance enhancements to speed up interprocedural analysis

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

	- New memory error checks such as use-after-free with C++ 'delete'.
	- Detection of mismatched allocators and deallocators (e.g., using 'new' with
	'free()', 'malloc()' with 'delete').
	- Additional checks for misuses of Apple Foundation framework collection APIs.

	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>`_.