=====================================
Clang 3.6 (In-Progress) Release Notes
=====================================

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

.. warning::

   These are in-progress notes for the upcoming Clang 3.6 release. You may
   prefer the `Clang 3.5 Release Notes
   <http://llvm.org/releases/3.5.0/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 3.6. 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 3.6?
========================

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

- The __has_attribute built-in macro no longer queries for attributes across
  multiple attribute syntaxes (GNU, C++11, __declspec, etc). Instead, it only
  queries GNU-style attributes. With the addition of __has_cpp_attribute and
  __has_declspec_attribute, this allows for more precise coverage of attribute
  syntax querying.

- clang-format now supports formatting Java code.


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 3.5 release include:

-  ...

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

The option ....

The __EXCEPTIONS macro
----------------------
``__EXCEPTIONS`` is now defined when landing pads are emitted, not when c++ exceptions are enabled. The two can be different in Objective-C files: If C++ exceptions are disabled but Objective-C exceptions are enabled, landing pads will be emitted. Clang 3.6 is switching the behavior of ``__EXCEPTIONS``. Clang 3.5 confusingly changed the behavior of ``has_feature(cxx_exceptions)``, which used to be set if landing pads were emitted, but is now set if C++ exceptions are enabled. So there are 3 cases:

Clang before 3.5:
   ``__EXCEPTIONS`` is set if C++ exceptions are enabled, ``cxx_exceptions`` enabled if C++ or ObjC exceptions are enabled

Clang 3.5:
   ``__EXCEPTIONS`` is set if C++ exceptions are enabled, ``cxx_exceptions`` enabled if C++ exceptions are enabled

Clang 3.6:
   ``__EXCEPTIONS`` is set if C++ or ObjC exceptions are enabled, ``cxx_exceptions`` enabled if C++ exceptions are enabled

To reliably test if C++ exceptions are enabled, use ``__EXCEPTIONS && __has_feature(cxx_exceptions)``, else things won't work in all versions of clang in Objective-C++ files.


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

Clang now supports the ...

Windows Support
---------------

- Many, many bug fixes

- Basic support for DWARF debug information in COFF files


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

...

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

...

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

- Clang now supports putting identical constructors and destructors in
  the C5/D5 comdat, reducing code duplication.

- Clang will put individual ``.init_array/.ctors`` sections in
  comdats, reducing code duplication and speeding up startup.

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 3.5 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
---------------

...

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>`_.
