1 ===================================== 2 Clang 3.9 (In-Progress) Release Notes 3 ===================================== 4 5 .. contents:: 6 :local: 7 :depth: 2 8 9 Written by the `LLVM Team <http://llvm.org/>`_ 10 11 .. warning:: 12 13 These are in-progress notes for the upcoming Clang 3.9 release. You may 14 prefer the `Clang 3.8 Release Notes 15 <http://llvm.org/releases/3.8.0/tools/clang/docs/ReleaseNotes.html>`_. 16 17 Introduction 18 ============ 19 20 This document contains the release notes for the Clang C/C++/Objective-C 21 frontend, part of the LLVM Compiler Infrastructure, release 3.9. Here we 22 describe the status of Clang in some detail, including major 23 improvements from the previous release and new feature work. For the 24 general LLVM release notes, see `the LLVM 25 documentation <http://llvm.org/docs/ReleaseNotes.html>`_. All LLVM 26 releases may be downloaded from the `LLVM releases web 27 site <http://llvm.org/releases/>`_. 28 29 For more information about Clang or LLVM, including information about 30 the latest release, please check out the main please see the `Clang Web 31 Site <http://clang.llvm.org>`_ or the `LLVM Web 32 Site <http://llvm.org>`_. 33 34 Note that if you are reading this file from a Subversion checkout or the 35 main Clang web page, this document applies to the *next* release, not 36 the current one. To see the release notes for a specific release, please 37 see the `releases page <http://llvm.org/releases/>`_. 38 39 What's New in Clang 3.9? 40 ======================== 41 42 Some of the major new features and improvements to Clang are listed 43 here. Generic improvements to Clang as a whole or to its underlying 44 infrastructure are described first, followed by language-specific 45 sections with improvements to Clang's support for those languages. 46 47 Major New Features 48 ------------------ 49 50 - Clang will no longer passes --build-id by default to the linker. In modern 51 linkers that is a relatively expensive option. It can be passed explicitly 52 with -Wl,--build-id. To have clang always pass it, build clang with 53 -DENABLE_LINKER_BUILD_ID. 54 55 Improvements to Clang's diagnostics 56 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 57 58 Clang's diagnostics are constantly being improved to catch more issues, 59 explain them more clearly, and provide more accurate source information 60 about them. The improvements since the 3.7 release include: 61 62 - ... 63 64 New Compiler Flags 65 ------------------ 66 67 The option .... 68 69 70 New Pragmas in Clang 71 ----------------------- 72 73 Clang now supports the ... 74 75 Windows Support 76 --------------- 77 78 Clang's support for building native Windows programs ... 79 80 TLS is enabled for Cygwin defaults to -femulated-tls. 81 82 83 C Language Changes in Clang 84 --------------------------- 85 The -faltivec and -maltivec flags no longer silently include altivec.h on Power platforms. 86 87 `RenderScript 88 <https://developer.android.com/guide/topics/renderscript/compute.html>`_ 89 support added to the Frontend and enabled by the '-x renderscript' option or 90 the '.rs' file extension. 91 92 ... 93 94 C11 Feature Support 95 ^^^^^^^^^^^^^^^^^^^ 96 97 ... 98 99 C++ Language Changes in Clang 100 ----------------------------- 101 102 - Clang now enforces the rule that a *using-declaration* cannot name an enumerator of a 103 scoped enumeration. 104 105 .. code-block:: c++ 106 107 namespace Foo { enum class E { e }; } 108 namespace Bar { 109 using Foo::E::e; // error 110 constexpr auto e = Foo::E::e; // ok 111 } 112 113 - Clang now enforces the rule that an enumerator of an unscoped enumeration declared at 114 class scope can only be named by a *using-declaration* in a derived class. 115 116 .. code-block:: c++ 117 118 class Foo { enum E { e }; } 119 using Foo::e; // error 120 static constexpr auto e = Foo::e; // ok 121 122 ... 123 124 C++1z Feature Support 125 ^^^^^^^^^^^^^^^^^^^^^ 126 127 Clang's experimental support for the upcoming C++1z standard can be enabled with ``-std=c++1z``. 128 Changes to C++1z features since Clang 3.8: 129 130 - The ``[[fallthrough]]``, ``[[nodiscard]]``, and ``[[maybe_unused]]`` attributes are 131 supported in C++11 onwards, and are largely synonymous with Clang's existing attributes 132 ``[[clang::fallthrough]]``, ``[[gnu::warn_unused_result]]``, and ``[[gnu::unused]]``. 133 Use ``-Wimplicit-fallthrough`` to warn on unannotated fallthrough within ``switch`` 134 statements. 135 136 - In C++1z mode, aggregate initialization can be performed for classes with base classes: 137 138 .. code-block:: c++ 139 140 struct A { int n; }; 141 struct B : A { int x, y; }; 142 B b = { 1, 2, 3 }; // b.n == 1, b.x == 2, b.y == 3 143 144 - The range in a range-based ``for`` statement can have different types for its ``begin`` 145 and ``end`` iterators. This is permitted as an extension in C++11 onwards. 146 147 - Lambda-expressions can explicitly capture ``*this`` (to capture the surrounding object 148 by copy). This is permitted as an extension in C++11 onwards. 149 150 - Objects of enumeration type can be direct-list-initialized from a value of the underlying 151 type. ``E{n}`` is equivalent to ``E(n)``, except that it implies a check for a narrowing 152 conversion. 153 154 - Unary *fold-expression*\s over an empty pack are now rejected for all operators 155 other than ``&&``, ``||``, and ``,``. 156 157 ... 158 159 Objective-C Language Changes in Clang 160 ------------------------------------- 161 162 ... 163 164 OpenCL C Language Changes in Clang 165 ---------------------------------- 166 167 ... 168 169 OpenMP Support in Clang 170 ---------------------------------- 171 172 Added support for all non-offloading features from OpenMP 4.5, including using 173 data members in private clauses of non-static member functions. Additionally, 174 data members can be used as loop control variables in loop-based directives. 175 176 Currently Clang supports OpenMP 3.1 and all non-offloading features of 177 OpenMP 4.0/4.5. Offloading features are under development. Clang defines macro 178 _OPENMP and sets it to OpenMP 3.1 (in accordance with OpenMP standard) by 179 default. User may change this value using ``-fopenmp-version=[31|40|45]`` option. 180 181 The codegen for OpenMP constructs was significantly improved to produce much 182 more stable and faster code. 183 184 Internal API Changes 185 -------------------- 186 187 These are major API changes that have happened since the 3.8 release of 188 Clang. If upgrading an external codebase that uses Clang as a library, 189 this section should help get you past the largest hurdles of upgrading. 190 191 - ... 192 193 AST Matchers 194 ------------ 195 196 - has and hasAnyArgument: Matchers no longer ignores parentheses and implicit 197 casts on the argument before applying the inner matcher. The fix was done to 198 allow for greater control by the user. In all existing checkers that use this 199 matcher all instances of code ``hasAnyArgument(<inner matcher>)`` or 200 ``has(<inner matcher>)`` must be changed to 201 ``hasAnyArgument(ignoringParenImpCasts(<inner matcher>))`` or 202 ``has(ignoringParenImpCasts(<inner matcher>))``. 203 204 ... 205 206 libclang 207 -------- 208 209 ... 210 211 Static Analyzer 212 --------------- 213 214 ... 215 216 Core Analysis Improvements 217 ========================== 218 219 - ... 220 221 New Issues Found 222 ================ 223 224 - ... 225 226 Python Binding Changes 227 ---------------------- 228 229 The following methods have been added: 230 231 - ... 232 233 Significant Known Problems 234 ========================== 235 236 Additional Information 237 ====================== 238 239 A wide variety of additional information is available on the `Clang web 240 page <http://clang.llvm.org/>`_. The web page contains versions of the 241 API documentation which are up-to-date with the Subversion version of 242 the source code. You can access versions of these documents specific to 243 this release by going into the "``clang/docs/``" directory in the Clang 244 tree. 245 246 If you have any questions or comments about Clang, please feel free to 247 contact us via the `mailing 248 list <http://lists.llvm.org/mailman/listinfo/cfe-dev>`_. 249
