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diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst index 5ff136e..8c47d69 100644 --- a/docs/ReleaseNotes.rst +++ b/docs/ReleaseNotes.rst @@ -1,6 +1,6 @@ -======================= -Clang 3.5 Release Notes -======================= +===================================== +Clang 3.6 (In-Progress) Release Notes +===================================== .. contents:: :local: @@ -8,11 +8,17 @@ Clang 3.5 Release Notes 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/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 3.5. Here we +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 @@ -30,7 +36,7 @@ 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 3.5? +What's New in Clang 3.6? ======================== Some of the major new features and improvements to Clang are listed @@ -41,213 +47,104 @@ sections with improvements to Clang's support for those languages. Major New Features ------------------ -- Clang uses the new MingW ABI - GCC 4.7 changed the mingw ABI. Clang 3.4 and older use the GCC 4.6 - ABI. Clang 3.5 and newer use the GCC 4.7 abi. - -- The __has_attribute feature test is now target-aware. Older versions of Clang - would return true when the attribute spelling was known, regardless of whether - the attribute was available to the specific target. Clang now returns true - only when the attribute pertains to the current compilation target. - -- Clang 3.5 now has parsing and semantic-analysis support for all OpenMP 3.1 - pragmas (except atomics and ordered). LLVM's OpenMP runtime library, - originally developed by Intel, has been modified to work on ARM, PowerPC, - as well as X86. Code generation support is minimal at this point and will - continue to be developed for 3.6, along with the rest of OpenMP 3.1. - Support for OpenMP 4.0 features, such as SIMD and target accelerator - directives, is also in progress. Contributors to this work include AMD, - Argonne National Lab., IBM, Intel, Texas Instruments, University of Houston - and many others. +- 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. + 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 3.4 release include: - -- GCC compatibility: Clang displays a warning on unsupported gcc - optimization flags instead of an error. - -- Remarks system: Clang supports `-R` flags for enabling remarks. These are - diagnostic messages that provide information about the compilation process, - but don't suggest that a problem has been detected. As such, they cannot - be upgraded to errors with `-Werror` or `-Rerror`. A `-Reverything` flag - is provided (paralleling `-Weverything`) to turn on all remarks. - -- New remark `-Rpass`: Clang provides information about decisions made by - optimization passes during compilation. See :ref:`opt_rpass`. - -- New warning `-Wabsolute-value`: Clang warns about incorrect or useless usage - of the absolute functions (`abs`, `fabsf`, etc). - - .. code-block:: c - - #include <stdlib.h> - void foo() { - unsigned int i=0; - abs(i); - } - - returns - `warning: taking the absolute value of unsigned type 'unsigned int' has no effect [-Wabsolute-value]` - - or - - .. code-block:: c - - #include <stdlib.h> - void plop() { - long long i=0; - abs(i); - } - - returns - `warning: absolute value function 'abs' given an argument of type 'long long' but has parameter of type 'int' which may cause truncation of value [-Wabsolute-value] use function 'llabs' instead` - -- New warning `-Wtautological-pointer-compare`: - - .. code-block:: c++ - - #include <stddef.h> - void foo() { - int arr[5]; - int x; - // warn on these conditionals - if (foo); - if (arr); - if (&x); - if (foo == NULL); - if (arr == NULL); - if (&x == NULL); - } - - returns - `warning: comparison of address of 'x' equal to a null pointer is always false [-Wtautological-pointer-compare]` - -- New warning `-Wtautological-undefined-compare`: - - .. code-block:: c++ - - #include <stddef.h> - void f(int &x) { - if (&x == nullptr) { } - } - - returns - `warning: reference cannot be bound to dereferenced null pointer in well-defined C++ code; comparison may be assumed to always evaluate to false [-Wtautological-undefined-compare]` +about them. The improvements since the 3.5 release include: - ... New Compiler Flags ------------------ -The integrated assembler is now turned on by default on ARM (and Thumb), -so the use of the option `-fintegrated-as` is now redundant on those -architectures. This is an important move to both *eat our own dog food* -and to ease cross-compilation tremendously. +The option .... -We are aware of the problems that this may cause for code bases that -rely on specific GNU syntax or extensions, and we're working towards -getting them all fixed. Please, report bugs or feature requests if -you find anything. In the meantime, use `-fno-integrated-as` to revert -back the call to GNU assembler. -In order to provide better diagnostics, the integrated assembler validates -inline assembly when the integrated assembler is enabled. Because this is -considered a feature of the compiler, it is controlled via the `fintegrated-as` -and `fno-integrated-as` flags which enable and disable the integrated assembler -respectively. `-integrated-as` and `-no-integrated-as` are now considered -legacy flags (but are available as an alias to prevent breaking existing users), -and users are encouraged to switch to the equivalent new feature flag. +New Pragmas in Clang +----------------------- -Deprecated flags `-faddress-sanitizer`, `-fthread-sanitizer`, -`-fcatch-undefined-behavior` and `-fbounds-checking` were removed in favor of -`-fsanitize=` family of flags. +Clang now supports the ... -It is now possible to get optimization reports from the major transformation -passes via three new flags: `-Rpass`, `-Rpass-missed` and `-Rpass-analysis`. -These flags take a POSIX regular expression which indicates the name -of the pass (or passes) that should emit optimization remarks. +Windows Support +--------------- -Options `-u` and `-z` are forwarded to the linker on gnutools toolchains. +Clang's support for building native Windows programs ... -New Pragmas in Clang ------------------------ +C Language Changes in Clang +--------------------------- + +... -Loop optimization hints can be specified using the new `#pragma clang loop` -directive just prior to the desired loop. The directive allows vectorization and -interleaving to be enabled or disabled. Vector width as well as interleave count -can be manually specified. See :ref:`langext-pragma-loop` for details. +C11 Feature Support +^^^^^^^^^^^^^^^^^^^ + +... C++ Language Changes in Clang ----------------------------- -- Reference parameters and return values from functions are more aggressively - assumed to refer to valid objects when optimizing. Clang will attempt to - issue a warning by default if it sees null checks being performed on - references, and `-fsanitize=null` can be used to detect null references - being formed at runtime. +- ... -C++17 Feature Support +C++11 Feature Support ^^^^^^^^^^^^^^^^^^^^^ -Clang has experimental support for some proposed C++1z (tentatively, C++17) -features. This support can be enabled using the `-std=c++1z` flag. The -supported features are: - -- `static_assert(expr)` with no message - -- `for (identifier : range)` as a synonym for `for (auto &&identifier : range)` +... -- `template<template<...> typename>` as a synonym for `template<template<...> class>` +Objective-C Language Changes in Clang +------------------------------------- -Additionally, trigraphs are not recognized by default in this mode. -`-ftrigraphs` can be used if you need to parse legacy code that uses trigraphs. -Note that these features may be changed or removed in future Clang releases -without notice. +... -OpenMP C/C++ Language Changes in Clang --------------------------------------- - -- `Status of supported OpenMP constructs - <https://github.com/clang-omp/clang/wiki/Status-of-supported-OpenMP-constructs>`_. +OpenCL C Language Changes in Clang +---------------------------------- +... Internal API Changes -------------------- -These are major API changes that have happened since the 3.4 release of +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. -- Clang uses `std::unique_ptr<T>` in many places where it used to use - raw `T *` pointers. +... + +libclang +-------- + +... Static Analyzer --------------- -Check for code testing a variable for 0 after using it as a denominator. -This new checker, alpha.core.TestAfterDivZero, catches issues like this: +... + +Core Analysis Improvements +========================== -.. code-block:: c +- ... - int sum = ... - int avg = sum / count; // potential division by zero... - if (count == 0) { ... } // ...caught here +New Issues Found +================ +- ... -The `-analyzer-config` options are now passed from scan-build through to -ccc-analyzer and then to Clang. +Python Binding Changes +---------------------- -With the option `-analyzer-config stable-report-filename=true`, -instead of `report-XXXXXX.html`, scan-build/clang analyzer generate -`report-<filename>-<function, method name>-<function position>-<id>.html`. -(id = i++ for several issues found in the same function/method). +The following methods have been added: -List the function/method name in the index page of scan-build. +- ... Significant Known Problems ========================== |
