diff options
Diffstat (limited to 'docs/ReleaseNotes.rst')
| -rw-r--r-- | docs/ReleaseNotes.rst | 249 |
1 files changed, 80 insertions, 169 deletions
diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst index e4fa953f9319..11ee88f4ae20 100644 --- a/docs/ReleaseNotes.rst +++ b/docs/ReleaseNotes.rst @@ -1,6 +1,6 @@ -======================= -Clang 3.9 Release Notes -======================= +======================================= +Clang 4.0.0 (In-Progress) Release Notes +======================================= .. contents:: :local: @@ -8,11 +8,17 @@ Clang 3.9 Release Notes Written by the `LLVM Team <http://llvm.org/>`_ +.. warning:: + + These are in-progress notes for the upcoming Clang 4.0.0 release. You may + prefer the `Clang 3.9 Release Notes + <http://llvm.org/releases/3.9.0/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 3.9. Here we +frontend, part of the LLVM Compiler Infrastructure, release 4.0.0. 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 @@ -25,8 +31,13 @@ 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>`_. -What's New in Clang 3.9? -======================== +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 4.0.0? +========================== Some of the major new features and improvements to Clang are listed here. Generic improvements to Clang as a whole or to its underlying @@ -36,224 +47,124 @@ sections with improvements to Clang's support for those languages. Major New Features ------------------ -- Clang will no longer pass ``--build-id`` by default to the linker. In modern - linkers that is a relatively expensive option. It can be passed explicitly - with ``-Wl,--build-id``. To have clang always pass it, build clang with - ``-DENABLE_LINKER_BUILD_ID``. -- On Itanium ABI targets, attribute abi_tag is now supported for compatibility - with GCC. Clang's implementation of abi_tag is mostly compatible with GCC ABI - version 10. +- ... 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 3.8 release include: +- ... + +New Compiler Flags +------------------ + +The option -Og has been added to optimize the debugging experience. +For now, this option is exactly the same as -O1. However, in the future, +some other optimizations might be enabled or disabled. -- ``-Wcomma`` is a new warning to show most uses of the builtin comma operator. -- ``-Wfloat-conversion`` has two new sub-warnings to give finer grain control for - floating point to integer conversion warnings. +The option .... - - ``-Wfloat-overflow-conversion`` detects when a constant floating point value - is converted to an integer type and will overflow the target type. +New Pragmas in Clang +----------------------- + +Clang now supports the ... - - ``-Wfloat-zero-conversion`` detects when a non-zero floating point value is - converted to a zero integer value. Attribute Changes in Clang -------------------------- -- The ``nodebug`` attribute may now be applied to static, global, and local - variables (but not parameters or non-static data members). This will suppress - all debugging information for the variable (and its type, if there are no - other uses of the type). - +- ... Windows Support --------------- -TLS is enabled for Cygwin and defaults to -femulated-tls. +Clang's support for building native Windows programs ... -Proper support, including correct mangling and overloading, added for -MS-specific "__unaligned" type qualifier. - -clang-cl now has limited support for the precompiled header flags /Yc, /Yu, and -/Fp. If the precompiled header is passed on the compile command with /FI, then -the precompiled header flags are honored. But if the precompiled header is -included by an ``#include <stdafx.h>`` in each source file instead of by a -``/FIstdafx.h`` flag, these flag continue to be ignored. - -clang-cl has a new flag, ``/imsvc <dir>``, for adding a directory to the system -include search path (where warnings are disabled by default) without having to -set ``%INCLUDE%``. C Language Changes in Clang --------------------------- -The -faltivec and -maltivec flags no longer silently include altivec.h on Power platforms. - -`RenderScript -<https://developer.android.com/guide/topics/renderscript/compute.html>`_ -support has been added to the frontend and enabled by the '-x renderscript' -option or the '.rs' file extension. - - -C++ Language Changes in Clang ------------------------------ - -- Clang now enforces the rule that a *using-declaration* cannot name an enumerator of a - scoped enumeration. - .. code-block:: c++ +- ... - namespace Foo { enum class E { e }; } - namespace Bar { - using Foo::E::e; // error - constexpr auto e = Foo::E::e; // ok - } +... -- Clang now enforces the rule that an enumerator of an unscoped enumeration declared at - class scope can only be named by a *using-declaration* in a derived class. +C11 Feature Support +^^^^^^^^^^^^^^^^^^^ - .. code-block:: c++ +... - class Foo { enum E { e }; } - using Foo::e; // error - static constexpr auto e = Foo::e; // ok +C++ Language Changes in Clang +----------------------------- +... C++1z Feature Support ^^^^^^^^^^^^^^^^^^^^^ -Clang's experimental support for the upcoming C++1z standard can be enabled with ``-std=c++1z``. -Changes to C++1z features since Clang 3.8: - -- The ``[[fallthrough]]``, ``[[nodiscard]]``, and ``[[maybe_unused]]`` attributes are - supported in C++11 onwards, and are largely synonymous with Clang's existing attributes - ``[[clang::fallthrough]]``, ``[[gnu::warn_unused_result]]``, and ``[[gnu::unused]]``. - Use ``-Wimplicit-fallthrough`` to warn on unannotated fallthrough within ``switch`` - statements. - -- In C++1z mode, aggregate initialization can be performed for classes with base classes: - - .. code-block:: c++ - - struct A { int n; }; - struct B : A { int x, y; }; - B b = { 1, 2, 3 }; // b.n == 1, b.x == 2, b.y == 3 - -- The range in a range-based ``for`` statement can have different types for its ``begin`` - and ``end`` iterators. This is permitted as an extension in C++11 onwards. - -- Lambda-expressions can explicitly capture ``*this`` (to capture the surrounding object - by copy). This is permitted as an extension in C++11 onwards. +... -- Objects of enumeration type can be direct-list-initialized from a value of the underlying - type. ``E{n}`` is equivalent to ``E(n)``, except that it implies a check for a narrowing - conversion. +Objective-C Language Changes in Clang +------------------------------------- -- Unary *fold-expression*\s over an empty pack are now rejected for all operators - other than ``&&``, ``||``, and ``,``. +... OpenCL C Language Changes in Clang ---------------------------------- -Clang now has support for all OpenCL 2.0 features. In particular, the following -features have been completed since the previous release: - -- Pipe builtin functions (s6.13.16.2-4). -- Dynamic parallelism support via the ``enqueue_kernel`` Clang builtin function, - as well as the kernel query functions from s6.13.17.6. -- Address space conversion functions ``to_{global/local/private}``. -- ``nosvm`` attribute support. -- Improved diagnostic and generation of Clang Blocks used in OpenCL kernel code. -- ``opencl_unroll_hint`` pragma. - -Several miscellaneous improvements have been made: - -- Supported extensions are now part of the target representation to give correct - diagnostics for unsupported target features during compilation. For example, - when compiling for a target that does not support the double precision - floating point extension, Clang will give an error when encountering the - ``cl_khr_fp64`` pragma. Several missing extensions were added covering up to - and including OpenCL 2.0. -- Clang now comes with the OpenCL standard headers declaring builtin types and - functions up to and including OpenCL 2.0 in ``lib/Headers/opencl-c.h``. By - default, Clang will not include this header. It can be included either using - the regular ``-I<path to header location>`` directive or (if the default one - from installation is to be used) using the ``-finclude-default-header`` - frontend flag. - - Example: - - .. code-block:: none - - echo "bool is_wg_uniform(int i){return get_enqueued_local_size(i)==get_local_size(i);}" > test.cl - clang -cc1 -finclude-default-header -cl-std=CL2.0 test.cl - - All builtin function declarations from OpenCL 2.0 will be automatically - visible in test.cl. -- Image types have been improved with better diagnostics for access qualifiers. - Images with one access qualifier type cannot be used in declarations for - another type. Also qualifiers are now propagated from the frontend down to - libraries and backends. -- Diagnostic improvements for OpenCL types, address spaces and vectors. -- Half type literal support has been added. For example, ``1.0h`` represents a - floating point literal in half precision, i.e., the value ``0xH3C00``. -- The Clang driver now accepts OpenCL compiler options ``-cl-*`` (following the - OpenCL Spec v1.1-1.2 s5.8). For example, the ``-cl-std=CL1.2`` option from the - spec enables compilation for OpenCL 1.2, or ``-cl-mad-enable`` will enable - fusing multiply-and-add operations. -- Clang now uses function metadata instead of module metadata to propagate - information related to OpenCL kernels e.g. kernel argument information. +... OpenMP Support in Clang ---------------------------------- -Added support for all non-offloading features from OpenMP 4.5, including using -data members in private clauses of non-static member functions. Additionally, -data members can be used as loop control variables in loop-based directives. +... -Currently Clang supports OpenMP 3.1 and all non-offloading features of -OpenMP 4.0/4.5. Offloading features are under development. Clang defines macro -_OPENMP and sets it to OpenMP 3.1 (in accordance with OpenMP standard) by -default. User may change this value using ``-fopenmp-version=[31|40|45]`` option. +Internal API Changes +-------------------- -The codegen for OpenMP constructs was significantly improved to produce much -more stable and faster code. +These are major API changes that have happened since the 3.9 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. + +- ... AST Matchers ------------ -- has and hasAnyArgument: Matchers no longer ignore parentheses and implicit - casts on the argument before applying the inner matcher. The fix was done to - allow for greater control by the user. In all existing checkers that use this - matcher all instances of code ``hasAnyArgument(<inner matcher>)`` or - ``has(<inner matcher>)`` must be changed to - ``hasAnyArgument(ignoringParenImpCasts(<inner matcher>))`` or - ``has(ignoringParenImpCasts(<inner matcher>))``. +... + +libclang +-------- + +... + +With the option --show-description, scan-build's list of defects will also +show the description of the defects. + Static Analyzer --------------- -The analyzer now checks for incorrect usage of MPI APIs in C and C++. This -check can be enabled by passing the following command to scan-build: -``-enable-checker optin.mpi.MPI-Checker.`` +... + +Core Analysis Improvements +========================== + +- ... + +New Issues Found +================ -The analyzer now checks for improper instance cleanup up in Objective-C -``-dealloc`` methods under manual retain/release. +- ... -On Windows, checks for memory leaks, double frees, and use-after-free problems -are now enabled by default. +Python Binding Changes +---------------------- -The analyzer now includes scan-build-py, an experimental reimplementation of -scan-build in Python that also creates compilation databases. +The following methods have been added: -The scan-build tool now supports a ``--force-analyze-debug-code`` flag that -forces projects to analyze in debug mode. This flag leaves in assertions and so -typically results in fewer false positives. +- ... +Significant Known Problems +========================== Additional Information ====================== |