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diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst index e764a09..ec0dbff 100644 --- a/docs/ReleaseNotes.rst +++ b/docs/ReleaseNotes.rst @@ -1,40 +1,56 @@ ======================= -Clang 3.3 Release Notes +Clang 3.4 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? +frontend, part of the LLVM Compiler Infrastructure, release 3.4. 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 `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 3.4? ======================== 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. +infrastructure are described first, followed by language-specific +sections with improvements to Clang's support for those languages. + +Last release which will build as C++98 +-------------------------------------- + +This is expected to be the last release of Clang which compiles using a C++98 +toolchain. We expect to start using some C++11 features in Clang starting after +this release. That said, we are committed to supporting a reasonable set of +modern C++ toolchains as the host compiler on all of the platforms. This will +at least include Visual Studio 2012 on Windows, and Clang 3.1 or GCC 4.7.x on +Mac and Linux. The final set of compilers (and the C++11 features they support) +is not set in stone, but we wanted users of Clang to have a heads up that the +next release will involve a substantial change in the host toolchain +requirements. + +Note that this change is part of a change for the entire LLVM project, not just +Clang. Major New Features ------------------ @@ -44,90 +60,210 @@ 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: +about them. The improvements since the 3.3 release include: + +- -Wheader-guard warns on mismatches between the #ifndef and #define lines + in a header guard. + + .. code-block:: c + + #ifndef multiple + #define multi + #endif + + returns + `warning: 'multiple' is used as a header guard here, followed by #define of a different macro [-Wheader-guard]` + +- -Wlogical-not-parentheses warns when a logical not ('!') only applies to the + left-hand side of a comparison. This warning is part of -Wparentheses. + + .. code-block:: c++ + + int i1 = 0, i2 = 1; + bool ret; + ret = !i1 == i2; + + returns + `warning: logical not is only applied to the left hand side of this comparison [-Wlogical-not-parentheses]` + + +- Boolean increment, a deprecated feature, has own warning flag + -Wdeprecated-increment-bool, and is still part of -Wdeprecated. +- Clang errors on builtin enum increments and decrements. + + .. code-block:: c++ + + enum A { A1, A2 }; + void test() { + A a; + a++; + } + + returns + `error: must use 'enum' tag to refer to type 'A'` + + +- -Wloop-analysis now warns on for-loops which have the same increment or + decrement in the loop header as the last statement in the loop. + + .. code-block:: c + + void foo(char *a, char *b, unsigned c) { + for (unsigned i = 0; i < c; ++i) { + a[i] = b[i]; + ++i; + } + } + + returns + `warning: variable 'i' is incremented both in the loop header and in the loop body [-Wloop-analysis]` + +- -Wuninitialized now performs checking across field initializers to detect + when one field in used uninitialized in another field initialization. -Extended Identifiers: Unicode Support and Universal Character Names -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + .. code-block:: c++ -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``). + class A { + int x; + int y; + A() : x(y) {} + }; + + returns + `warning: field 'y' is uninitialized when used here [-Wuninitialized]` + +- Clang can detect initializer list use inside a macro and suggest parentheses + if possible to fix. +- Many improvements to Clang's typo correction facilities, such as: + + + Adding global namespace qualifiers so that corrections can refer to shadowed + or otherwise ambiguous or unreachable namespaces. + + Including accessible class members in the set of typo correction candidates, + so that corrections requiring a class name in the name specifier are now + possible. + + Allowing typo corrections that involve removing a name specifier. + + In some situations, correcting function names when a function was given the + wrong number of arguments, including situations where the original function + name was correct but was shadowed by a lexically closer function with the + same name yet took a different number of arguments. + + Offering typo suggestions for 'using' declarations. + + Providing better diagnostics and fixit suggestions in more situations when + a '->' was used instead of '.' or vice versa. + + Providing more relevant suggestions for typos followed by '.' or '='. + + Various performance improvements when searching for typo correction + candidates. + +- `LeakSanitizer <LeakSanitizer.html>`_ is an experimental memory leak detector + which can be combined with AddressSanitizer. + +New Compiler Flags +------------------ + +- Clang no longer special cases -O4 to enable lto. Explicitly pass -flto to + enable it. +- Clang no longer fails on >= -O5. These flags are mapped to -O3 instead. +- Command line "clang -O3 -flto a.c -c" and "clang -emit-llvm a.c -c" + are no longer equivalent. +- Clang now errors on unknown -m flags (``-munknown-to-clang``), + unknown -f flags (``-funknown-to-clang``) and unknown + options (``-what-is-this``). C Language Changes in Clang --------------------------- +- Added new checked arithmetic builtins for security critical applications. + 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. +- Fixed an ABI regression, introduced in Clang 3.2, which affected + member offsets for classes inheriting from certain classes with tail padding. + See PR16537. + +- Clang 3.4 supports the 2013-08-28 draft of the ISO WG21 SG10 feature test + macro recommendations. These aim to provide a portable method to determine + whether a compiler supports a language feature, much like Clang's + |has_feature macro|_. + +.. |has_feature macro| replace:: ``__has_feature`` macro +.. _has_feature macro: LanguageExtensions.html#has-feature-and-has-extension + +C++1y Feature Support +^^^^^^^^^^^^^^^^^^^^^ + +Clang 3.4 supports all the features in the current working draft of the +upcoming C++ standard, provisionally named C++1y. Support for the following +major new features has been added since Clang 3.3: + +- Generic lambdas and initialized lambda captures. +- Deduced function return types (``auto f() { return 0; }``). +- Generalized ``constexpr`` support (variable mutation and loops). +- Variable templates and static data member templates. +- Use of ``'`` as a digit separator in numeric literals. +- Support for sized ``::operator delete`` functions. + +In addition, ``[[deprecated]]`` is now accepted as a synonym for Clang's +existing ``deprecated`` attribute. + +Use ``-std=c++1y`` to enable C++1y mode. + +OpenCL C Language Changes in Clang +---------------------------------- + +- OpenCL C "long" now always has a size of 64 bit, and all OpenCL C + types are aligned as specified in the OpenCL C standard. Also, + "char" is now always signed. Internal API Changes -------------------- -These are major API changes that have happened since the 3.2 release of +These are major API changes that have happened since the 3.3 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. +Wide Character Types +^^^^^^^^^^^^^^^^^^^^ + +The ASTContext class now keeps track of two different types for wide character +types: WCharTy and WideCharTy. WCharTy represents the built-in wchar_t type +available in C++. WideCharTy is the type used for wide character literals; in +C++ it is the same as WCharTy, but in C99, where wchar_t is a typedef, it is an +integer type. 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. +The static analyzer has been greatly improved. This impacts the overall analyzer quality and reduces a number of false positives. +In particular, this release provides enhanced C++ support, reasoning about initializer lists, zeroing constructors, noreturn destructors and modeling of destructor calls on calls to delete. -Core Analysis Improvements -========================== +Clang Format +------------ + +Clang now includes a new tool ``clang-format`` which can be used to +automatically format C, C++ and Objective-C source code. ``clang-format`` +automatically chooses linebreaks and indentation and can be easily integrated +into editors, IDEs and version control systems. It supports several pre-defined +styles as well as precise style control using a multitude of formatting +options. ``clang-format`` itself is just a thin wrapper around a library which +can also be used directly from code refactoring and code translation tools. +More information can be found on `Clang Format's +site <http://clang.llvm.org/docs/ClangFormat.html>`_. + +Windows Support +--------------- -- 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 +- `clang-cl <UsersManual.html#clang-cl>`_ provides a new driver mode that is + designed for compatibility with Visual Studio's compiler, cl.exe. This driver + mode makes Clang accept the same kind of command-line options as cl.exe. The + installer will attempt to expose clang-cl in any Visual Studio installations + on the system as a Platform Toolset, e.g. "LLVM-vs2012". clang-cl targets the + Microsoft ABI by default. Please note that this driver mode and compatibility + with the MS ABI is highly experimental. -New Issues Found -================ +Python Binding Changes +---------------------- -- 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. +The following methods have been added: Significant Known Problems ========================== @@ -135,11 +271,13 @@ 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. +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 revision 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>`_. +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>`_. |
