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=====================================
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Clang 3.3 (In-Progress) Release Notes
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=====================================
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.. contents::
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:local:
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:depth: 2
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Written by the `LLVM Team <http://llvm.org/>`_
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.. warning::
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These are in-progress notes for the upcoming Clang 3.3 release. You may
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prefer the `Clang 3.2 Release Notes
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<http://llvm.org/releases/3.2/docs/ClangReleaseNotes.html>`_.
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Introduction
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============
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This document contains the release notes for the Clang C/C++/Objective-C
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frontend, part of the LLVM Compiler Infrastructure, release 3.3. Here we
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describe the status of Clang in some detail, including major
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improvements from the previous release and new feature work. For the
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general LLVM release notes, see `the LLVM
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documentation <http://llvm.org/docs/ReleaseNotes.html>`_. All LLVM
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releases may be downloaded from the `LLVM releases web
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site <http://llvm.org/releases/>`_.
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For more information about Clang or LLVM, including information about
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the latest release, please check out the main please see the `Clang Web
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Site <http://clang.llvm.org>`_ or the `LLVM Web
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Site <http://llvm.org>`_.
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Note that if you are reading this file from a Subversion checkout or the
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main Clang web page, this document applies to the *next* release, not
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the current one. To see the release notes for a specific release, please
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see the `releases page <http://llvm.org/releases/>`_.
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What's New in Clang 3.3?
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========================
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Some of the major new features and improvements to Clang are listed
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here. Generic improvements to Clang as a whole or to its underlying
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infrastructure are described first, followed by language-specific
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sections with improvements to Clang's support for those languages.
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Major New Features
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------------------
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Improvements to Clang's diagnostics
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Clang's diagnostics are constantly being improved to catch more issues,
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explain them more clearly, and provide more accurate source information
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about them. The improvements since the 3.2 release include:
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- ...
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Extended Identifiers: Unicode Support and Universal Character Names
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Clang 3.3 includes support for *extended identifiers* in C99 and C++.
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This feature allows identifiers to contain certain Unicode characters, as
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specified by the active language standard; these characters can be written
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directly in the source file using the UTF-8 encoding, or referred to using
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*universal character names* (``\u00E0``, ``\U000000E0``).
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New Compiler Flags
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------------------
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- ...
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C Language Changes in Clang
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---------------------------
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C11 Feature Support
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^^^^^^^^^^^^^^^^^^^
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...
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C++ Language Changes in Clang
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-----------------------------
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- Clang now correctly implements language linkage for functions and variables.
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This means that, for example, it is now possible to overload static functions
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declared in an ``extern "C"`` context. For backwards compatibility, an alias
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with the unmangled name is still emitted if it is the only one and has the
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``used`` attribute.
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C++11 Feature Support
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^^^^^^^^^^^^^^^^^^^^^
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...
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Objective-C Language Changes in Clang
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-------------------------------------
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...
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Internal API Changes
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--------------------
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These are major API changes that have happened since the 3.2 release of
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Clang. If upgrading an external codebase that uses Clang as a library,
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this section should help get you past the largest hurdles of upgrading.
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Value Casting
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^^^^^^^^^^^^^
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Certain type hierarchies (TypeLoc, CFGElement, ProgramPoint, and SVal) were
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misusing the llvm::cast machinery to perform undefined operations. Their APIs
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have been changed to use two member function templates that return values
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instead of pointers or references - "T castAs" and "Optional<T> getAs" (in the
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case of the TypeLoc hierarchy the latter is "T getAs" and you can use the
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boolean testability of a TypeLoc (or its 'validity') to verify that the cast
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succeeded). Essentially all previous 'cast' usage should be replaced with
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'castAs' and 'dyn_cast' should be replaced with 'getAs'. See r175462 for the
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first example of such a change along with many examples of how code was
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migrated to the new API.
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Storage Class
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^^^^^^^^^^^^^
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For each variable and function Clang used to keep the storage class as written
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in the source, the linkage and a semantic storage class. This was a bit
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redundant and the semantic storage class has been removed. The method
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getStorageClass now returns what is written in the source code for that decl.
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Wide Character Types
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^^^^^^^^^^^^^^^^^^^^
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The ASTContext class now keeps track of two different types for wide character
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types: WCharTy and WideCharTy. WCharTy represents the built-in wchar_t type
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available in C++. WideCharTy is the type used for wide character literals; in
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C++ it is the same as WCharTy, but in C99, where wchar_t is a typedef, it is an
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integer type.
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...
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libclang
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--------
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The clang_CXCursorSet_contains() function previously incorrectly returned 0
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if it contained a CXCursor, contrary to what the documentation stated. This
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has been fixed so that the function returns a non-zero value if the set
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contains a cursor. This is API breaking change, but matches the intended
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original behavior. Moreover, this also fixes the issue of an invalid CXCursorSet
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appearing to contain any CXCursor.
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Static Analyzer
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---------------
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The static analyzer (which contains additional code checking beyond compiler
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warnings) has improved significantly in both in the core analysis engine and
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also in the kinds of issues it can find.
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Core Analysis Improvements
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==========================
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- Support for interprocedural reasoning about constructors and destructors.
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- New false positive suppression mechanisms that reduced the number of false null pointer dereference warnings due to interprocedural analysis.
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- Major performance enhancements to speed up interprocedural analysis
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New Issues Found
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================
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- New memory error checks such as use-after-free with C++ 'delete'.
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- Detection of mismatched allocators and deallocators (e.g., using 'new' with 'free()', 'malloc()' with 'delete').
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- Additional checks for misuses of Apple Foundation framework collection APIs.
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Python Binding Changes
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----------------------
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The following methods have been added:
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- ...
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Significant Known Problems
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==========================
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Additional Information
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======================
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A wide variety of additional information is available on the `Clang web
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page <http://clang.llvm.org/>`_. The web page contains versions of the
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API documentation which are up-to-date with the Subversion version of
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the source code. You can access versions of these documents specific to
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this release by going into the "``clang/docs/``" directory in the Clang
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tree.
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If you have any questions or comments about Clang, please feel free to
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contact us via the `mailing
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list <http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev>`_.
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