| ======================================= |
| Clang 5.0.0 (In-Progress) Release Notes |
| ======================================= |
| |
| .. contents:: |
| :local: |
| :depth: 2 |
| |
| Written by the `LLVM Team <http://llvm.org/>`_ |
| |
| .. warning:: |
| |
| These are in-progress notes for the upcoming Clang 5 release. |
| Release notes for previous releases can be found on |
| `the Download Page <http://releases.llvm.org/download.html>`_. |
| |
| Introduction |
| ============ |
| |
| This document contains the release notes for the Clang C/C++/Objective-C |
| frontend, part of the LLVM Compiler Infrastructure, release 5.0.0. 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 |
| 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>`_. |
| |
| What's New in Clang 5.0.0? |
| ========================== |
| |
| Some of the major new features and improvements to Clang are listed |
| here. Generic improvements to Clang as a whole or to its underlying |
| infrastructure are described first, followed by language-specific |
| sections with improvements to Clang's support for those languages. |
| |
| Major New Features |
| ------------------ |
| |
| - Enhanced devirtualization with |
| `-fstrict-vtable-pointers <UsersManual.html#cmdoption-fstrict-vtable-pointers>`_. |
| Clang devirtualizes across different basic blocks, like loops: |
| |
| .. code-block:: c++ |
| |
| struct A { |
| virtual void foo(); |
| }; |
| void indirect(A &a, int n) { |
| for (int i = 0 ; i < n; i++) |
| a.foo(); |
| } |
| void test(int n) { |
| A a; |
| indirect(a, n); |
| } |
| |
| |
| - ... |
| |
| Improvements to ThinLTO (-flto=thin) |
| ------------------------------------ |
| - Integration with profile data (PGO). When available, profile data enables |
| more accurate function importing decisions, as well as cross-module indirect |
| call promotion. |
| - Significant build-time and binary-size improvements when compiling with debug |
| info (-g). |
| |
| Improvements to Clang's diagnostics |
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| |
| - -Wunused-lambda-capture warns when a variable explicitly captured |
| by a lambda is not used in the body of the lambda. |
| |
| New Compiler Flags |
| ------------------ |
| |
| The option .... |
| |
| New Pragmas in Clang |
| ----------------------- |
| |
| Clang now supports the ... |
| |
| |
| Attribute Changes in Clang |
| -------------------------- |
| |
| - ... |
| |
| Windows Support |
| --------------- |
| |
| Clang's support for building native Windows programs ... |
| |
| |
| C Language Changes in Clang |
| --------------------------- |
| |
| - ... |
| |
| ... |
| |
| C11 Feature Support |
| ^^^^^^^^^^^^^^^^^^^ |
| |
| ... |
| |
| C++ Language Changes in Clang |
| ----------------------------- |
| |
| ... |
| |
| C++1z Feature Support |
| ^^^^^^^^^^^^^^^^^^^^^ |
| |
| ... |
| |
| Objective-C Language Changes in Clang |
| ------------------------------------- |
| |
| ... |
| |
| OpenCL C Language Changes in Clang |
| ---------------------------------- |
| |
| ... |
| |
| OpenMP Support in Clang |
| ---------------------------------- |
| |
| ... |
| |
| Internal API Changes |
| -------------------- |
| |
| These are major API changes that have happened since the 4.0.0 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 |
| ------------ |
| |
| ... |
| |
| |
| clang-format |
| ------------ |
| |
| * Option **BreakBeforeInheritanceComma** added to break before ``:`` and ``,`` in case of |
| multiple inheritance in a class declaration. Enabled by default in the Mozilla coding style. |
| |
| +---------------------+----------------------------------------+ |
| | true | false | |
| +=====================+========================================+ |
| | .. code-block:: c++ | .. code-block:: c++ | |
| | | | |
| | class MyClass | class MyClass : public X, public Y { | |
| | : public X | }; | |
| | , public Y { | | |
| | }; | | |
| +---------------------+----------------------------------------+ |
| |
| * Align block comment decorations. |
| |
| +----------------------+---------------------+ |
| | Before | After | |
| +======================+=====================+ |
| | .. code-block:: c++ | .. code-block:: c++ | |
| | | | |
| | /* line 1 | /* line 1 | |
| | * line 2 | * line 2 | |
| | */ | */ | |
| +----------------------+---------------------+ |
| |
| * The :doc:`ClangFormatStyleOptions` documentation provides detailed examples for most options. |
| |
| * Namespace end comments are now added or updated automatically. |
| |
| +---------------------+---------------------+ |
| | Before | After | |
| +=====================+=====================+ |
| | .. code-block:: c++ | .. code-block:: c++ | |
| | | | |
| | namespace A { | namespace A { | |
| | int i; | int i; | |
| | int j; | int j; | |
| | } | } | |
| +---------------------+---------------------+ |
| |
| * Comment reflow support added. Overly long comment lines will now be reflown with the rest of |
| the paragraph instead of just broken. Option **ReflowComments** added and enabled by default. |
| |
| libclang |
| -------- |
| |
| ... |
| |
| |
| Static Analyzer |
| --------------- |
| |
| ... |
| |
| Undefined Behavior Sanitizer (UBSan) |
| ------------------------------------ |
| |
| - The Undefined Behavior Sanitizer has a new check for pointer overflow. This |
| check is on by default. The flag to control this functionality is |
| -fsanitize=pointer-overflow. |
| |
| Pointer overflow is an indicator of undefined behavior: when a pointer |
| indexing expression wraps around the address space, or produces other |
| unexpected results, its result may not point to a valid object. |
| |
| - UBSan has several new checks which detect violations of nullability |
| annotations. These checks are off by default. The flag to control this group |
| of checks is -fsanitize=nullability. The checks can be individially enabled |
| by -fsanitize=nullability-arg (which checks calls), |
| -fsanitize=nullability-assign (which checks assignments), and |
| -fsanitize=nullability-return (which checks return statements). |
| |
| - UBSan can now detect invalid loads from bitfields and from ObjC BOOLs. |
| |
| - UBSan can now avoid emitting unnecessary type checks in C++ class methods and |
| in several other cases where the result is known at compile-time. UBSan can |
| also avoid emitting unnecessary overflow checks in arithmetic expressions |
| with promoted integer operands. |
| |
| 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 <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. |
| |
| If you have any questions or comments about Clang, please feel free to |
| contact us via the `mailing |
| list <http://lists.llvm.org/mailman/listinfo/cfe-dev>`_. |
