===================================== Clang 3.6 (In-Progress) Release Notes ===================================== .. contents:: :local: :depth: 2 Written by the `LLVM Team `_ .. warning:: These are in-progress notes for the upcoming Clang 3.6 release. You may prefer the `Clang 3.5 Release Notes `_. 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 `_. All LLVM releases may be downloaded from the `LLVM releases web site `_. For more information about Clang or LLVM, including information about the latest release, please check out the main please see the `Clang Web Site `_ or the `LLVM 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 `_. 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 `_. 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 `_.