2021-05-04 00:32:36 +08:00
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========================================
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2021-01-27 11:37:08 +08:00
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Clang 13.0.0 (In-Progress) Release Notes
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2020-02-14 05:46:33 +08:00
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========================================
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.. contents::
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:local:
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:depth: 2
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Written by the `LLVM Team <https://llvm.org/>`_
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.. warning::
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2021-01-27 11:37:08 +08:00
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These are in-progress notes for the upcoming Clang 13 release.
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2020-02-14 05:46:33 +08:00
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Release notes for previous releases can be found on
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`the Download Page <https://releases.llvm.org/download.html>`_.
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Introduction
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============
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This document contains the release notes for the Clang C/C++/Objective-C
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2021-01-27 11:37:08 +08:00
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frontend, part of the LLVM Compiler Infrastructure, release 13.0.0. Here we
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2020-02-14 05:46:33 +08:00
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describe the status of Clang in some detail, including major
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improvements from the previous release and new feature work. For the
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general LLVM release notes, see `the LLVM
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documentation <https://llvm.org/docs/ReleaseNotes.html>`_. All LLVM
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releases may be downloaded from the `LLVM releases web
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site <https://llvm.org/releases/>`_.
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For more information about Clang or LLVM, including information about the
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latest release, please see the `Clang Web Site <https://clang.llvm.org>`_ or the
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`LLVM Web Site <https://llvm.org>`_.
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Note that if you are reading this file from a Git checkout or the
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main Clang web page, this document applies to the *next* release, not
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the current one. To see the release notes for a specific release, please
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see the `releases page <https://llvm.org/releases/>`_.
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2021-01-27 11:37:08 +08:00
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What's New in Clang 13.0.0?
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2020-02-14 05:46:33 +08:00
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===========================
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Some of the major new features and improvements to Clang are listed
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here. Generic improvements to Clang as a whole or to its underlying
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infrastructure are described first, followed by language-specific
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sections with improvements to Clang's support for those languages.
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Major New Features
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------------------
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2021-04-16 07:49:19 +08:00
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- Guaranteed tail calls are now supported with statement attributes
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``[[clang::musttail]]`` in C++ and ``__attribute__((musttail))`` in C. The
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attribute is applied to a return statement (not a function declaration),
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and an error is emitted if a tail call cannot be guaranteed, for example if
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the function signatures of caller and callee are not compatible. Guaranteed
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tail calls enable a class of algorithms that would otherwise use an
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arbitrary amount of stack space.
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2020-02-14 05:46:33 +08:00
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Improvements to Clang's diagnostics
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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2020-07-15 17:40:53 +08:00
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- ...
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2020-06-05 00:45:04 +08:00
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2020-02-14 05:46:33 +08:00
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Non-comprehensive list of changes in this release
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-------------------------------------------------
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2021-05-28 07:38:09 +08:00
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- The default value of _MSC_VER was raised from 1911 to 1914. MSVC 19.14 has the
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support to overaligned objects on x86_32 which is required for some LLVM
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passes.
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2020-05-26 02:44:35 +08:00
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2020-02-14 05:46:33 +08:00
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New Compiler Flags
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------------------
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2020-12-09 16:26:27 +08:00
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- ``-Wreserved-identifier`` emits warning when user code uses reserved
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identifiers.
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2020-07-11 21:07:27 +08:00
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2021-04-15 04:54:47 +08:00
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- ``-fstack-usage`` generates an extra .su file per input source file. The .su
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file contains frame size information for each function defined in the source
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file.
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2020-02-14 05:46:33 +08:00
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Deprecated Compiler Flags
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-------------------------
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- ...
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Modified Compiler Flags
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-----------------------
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2021-02-24 04:48:15 +08:00
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- -Wshadow now also checks for shadowed structured bindings
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2021-03-20 06:42:18 +08:00
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- ``-B <prefix>`` (when ``<prefix>`` is a directory) was overloaded to additionally
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detect GCC installations under ``<prefix>`` (``lib{,32,64}/gcc{,-cross}/$triple``).
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This behavior was incompatible with GCC, caused interop issues with
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``--gcc-toolchain``, and was thus dropped. Specify ``--gcc-toolchain=<dir>``
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instead. ``-B``'s other GCC-compatible semantics are preserved:
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``$prefix/$triple-$file`` and ``$prefix$file`` are searched for executables,
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libraries, includes, and data files used by the compiler.
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2020-02-14 05:46:33 +08:00
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2020-12-17 22:23:02 +08:00
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Removed Compiler Flags
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-------------------------
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2021-02-02 21:10:26 +08:00
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- The clang-cl ``/fallback`` flag, which made clang-cl invoke Microsoft Visual
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C++ on files it couldn't compile itself, has been removed.
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2020-12-17 22:23:02 +08:00
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2021-02-24 17:01:51 +08:00
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- ``-Wreturn-std-move-in-c++11``, which checked whether an entity is affected by
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`CWG1579 <https://wg21.link/CWG1579>`_ to become implicitly movable, has been
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removed.
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2020-02-14 05:46:33 +08:00
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New Pragmas in Clang
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--------------------
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- ...
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Attribute Changes in Clang
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--------------------------
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2021-01-27 11:37:08 +08:00
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- ...
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2020-02-14 05:46:33 +08:00
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2021-06-01 04:18:30 +08:00
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- Added support for C++11-style ``[[]]`` attributes on using-declarations, as a
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clang extension.
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2020-02-14 05:46:33 +08:00
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Windows Support
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---------------
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C Language Changes in Clang
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---------------------------
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2020-03-03 01:33:14 +08:00
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- ...
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2020-02-14 05:46:33 +08:00
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C++ Language Changes in Clang
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-----------------------------
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2021-04-14 19:18:23 +08:00
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- The oldest supported GNU libstdc++ is now 4.8.3 (released 2014-05-22).
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Clang workarounds for bugs in earlier versions have been removed.
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2020-07-15 17:40:53 +08:00
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- ...
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2020-02-14 05:46:33 +08:00
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2021-04-14 19:18:23 +08:00
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C++20 Feature Support
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^^^^^^^^^^^^^^^^^^^^^
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...
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C++2b Feature Support
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2020-02-14 05:46:33 +08:00
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^^^^^^^^^^^^^^^^^^^^^
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...
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Objective-C Language Changes in Clang
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-------------------------------------
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OpenCL C Language Changes in Clang
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----------------------------------
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...
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ABI Changes in Clang
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--------------------
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OpenMP Support in Clang
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-----------------------
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- ...
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CUDA Support in Clang
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---------------------
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- ...
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2020-08-21 04:37:51 +08:00
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X86 Support in Clang
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--------------------
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2021-01-27 11:37:08 +08:00
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- ...
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2020-10-30 12:58:05 +08:00
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2020-02-14 05:46:33 +08:00
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Internal API Changes
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--------------------
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2021-01-27 11:37:08 +08:00
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These are major API changes that have happened since the 12.0.0 release of
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2020-02-14 05:46:33 +08:00
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Clang. If upgrading an external codebase that uses Clang as a library,
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this section should help get you past the largest hurdles of upgrading.
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2020-07-15 17:40:53 +08:00
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- ...
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Removed a RecursiveASTVisitor feature to visit operator kinds with different methods
Summary:
This feature was only used in two places, but contributed a non-trivial
amount to the complexity of RecursiveASTVisitor, and was buggy (see my
recent patches where I was fixing the bugs that I noticed). I don't
think the convenience benefit of this feature is worth the complexity.
Besides complexity, another issue with the current state of
RecursiveASTVisitor is the non-uniformity in how it handles different
AST nodes. All AST nodes follow a regular pattern, but operators are
special -- and this special behavior not documented. Correct usage of
RecursiveASTVisitor relies on shadowing member functions with specific
names and signatures. Near misses don't cause any compile-time errors,
incorrectly named or typed methods are just silently ignored. Therefore,
predictability of RecursiveASTVisitor API is quite important.
This change reduces the size of the `clang` binary by 38 KB (0.2%) in
release mode, and by 7 MB (0.3%) in debug mode. The `clang-tidy` binary
is reduced by 205 KB (0.3%) in release mode, and by 5 MB (0.4%) in debug
mode. I don't think these code size improvements are significant enough
to justify this change on its own (for me, the primary motivation is
reducing code complexity), but they I think are a nice side-effect.
Reviewers: rsmith, sammccall, ymandel, aaron.ballman
Reviewed By: rsmith, sammccall, ymandel, aaron.ballman
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D82921
2020-07-03 23:01:01 +08:00
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2020-02-14 05:46:33 +08:00
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Build System Changes
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--------------------
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2021-01-27 11:37:08 +08:00
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These are major changes to the build system that have happened since the 12.0.0
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2020-02-14 05:46:33 +08:00
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release of Clang. Users of the build system should adjust accordingly.
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2021-03-02 02:20:53 +08:00
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- The option ``LIBCLANG_INCLUDE_CLANG_TOOLS_EXTRA`` no longer exists. There were
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two releases with that flag forced off, and no uses were added that forced it
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on. The recommended replacement is clangd.
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2020-07-15 17:40:53 +08:00
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- ...
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2020-02-14 05:46:33 +08:00
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AST Matchers
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------------
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2021-01-27 11:37:08 +08:00
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- ...
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2020-05-23 09:12:51 +08:00
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2020-02-14 05:46:33 +08:00
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clang-format
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------------
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2021-01-30 05:01:42 +08:00
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- Option ``SpacesInLineCommentPrefix`` has been added to control the
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number of spaces in a line comments prefix.
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2020-12-27 05:04:30 +08:00
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2021-02-02 21:41:55 +08:00
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- Option ``SortIncludes`` has been updated from a ``bool`` to an
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``enum`` with backwards compatibility. In addition to the previous
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2021-03-04 18:13:46 +08:00
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``true``/``false`` states (now ``CaseSensitive``/``Never``), a third
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state has been added (``CaseInsensitive``) which causes an alphabetical sort
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2021-02-02 21:41:55 +08:00
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with case used as a tie-breaker.
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.. code-block:: c++
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// Never (previously false)
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#include "B/A.h"
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#include "A/B.h"
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#include "a/b.h"
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#include "A/b.h"
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#include "B/a.h"
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2021-03-04 18:13:46 +08:00
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// CaseSensitive (previously true)
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2021-02-02 21:41:55 +08:00
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#include "A/B.h"
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#include "A/b.h"
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#include "B/A.h"
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#include "B/a.h"
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#include "a/b.h"
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2021-03-04 18:13:46 +08:00
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// CaseInsensitive
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2021-02-02 21:41:55 +08:00
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#include "A/B.h"
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#include "A/b.h"
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#include "a/b.h"
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#include "B/A.h"
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#include "B/a.h"
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2021-01-29 16:29:00 +08:00
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- ``BasedOnStyle: InheritParentConfig`` allows to use the ``.clang-format`` of
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the parent directories to overwrite only parts of it.
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[clang-format] [PR19056] Add support for access modifiers indentation
Adds support for coding styles that make a separate indentation level for access modifiers, such as Code::Blocks or QtCreator.
The new option, `IndentAccessModifiers`, if enabled, forces the content inside classes, structs and unions (“records”) to be indented twice while removing a level for access modifiers. The value of `AccessModifierOffset` is disregarded in this case, aiming towards an ease of use.
======
The PR (https://bugs.llvm.org/show_bug.cgi?id=19056) had an implementation attempt by @MyDeveloperDay already (https://reviews.llvm.org/D60225) but I've decided to start from scratch. They differ in functionality, chosen approaches, and even the option name. The code tries to re-use the existing functionality to achieve this behavior, limiting possibility of breaking something else.
Reviewed By: MyDeveloperDay, curdeius, HazardyKnusperkeks
Differential Revision: https://reviews.llvm.org/D94661
2021-02-26 16:05:35 +08:00
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- Option ``IndentAccessModifiers`` has been added to be able to give access
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modifiers their own indentation level inside records.
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2021-03-02 04:15:04 +08:00
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- Option ``ShortNamespaceLines`` has been added to give better control
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over ``FixNamespaceComments`` when determining a namespace length.
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2021-03-06 04:30:47 +08:00
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- Support for Whitesmiths has been improved, with fixes for ``namespace`` blocks
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and ``case`` blocks and labels.
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2021-04-15 23:27:20 +08:00
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- Option ``EmptyLineAfterAccessModifier`` has been added to remove, force or keep
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new lines after access modifiers.
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2021-04-16 16:02:02 +08:00
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- Checks for newlines in option ``EmptyLineBeforeAccessModifier`` are now based
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on the formatted new lines and not on the new lines in the file. (Fixes
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https://llvm.org/PR41870.)
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2021-04-29 14:57:33 +08:00
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- Option ``SpacesInAngles`` has been improved, it now accepts ``Leave`` value
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that allows to keep spaces where they are already present.
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2021-05-03 23:59:32 +08:00
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- Option ``AllowShortIfStatementsOnASingleLine`` has been improved, it now
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accepts ``AllIfsAndElse`` value that allows to put "else if" and "else" short
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statements on a single line. (Fixes https://llvm.org/PR50019.)
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2021-05-27 04:22:44 +08:00
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- Option ``BreakInheritanceList`` gets a new style, ``AfterComma``. It breaks
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only after the commas that separate the base-specifiers.
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2021-05-05 08:41:40 +08:00
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- ``git-clang-format`` no longer formats changes to symbolic links. (Fixes
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https://llvm.org/PR46992.)
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[clang-format] Fix PointerAlignmentRight with AlignConsecutiveDeclarations
This re-applies the old patch D27651, which was never landed, into the
latest "main" branch, without understanding the code. I just applied
the changes "mechanically" and made it compiling again.
This makes the right pointer alignment working as expected.
Fixes https://llvm.org/PR27353
For instance
const char* const* v1;
float const* v2;
SomeVeryLongType const& v3;
was formatted as
const char *const * v1;
float const * v2;
SomeVeryLongType const &v3;
This patch keep the *s or &s aligned to the right, next to their variable.
The above example is now formatted as
const char *const *v1;
float const *v2;
SomeVeryLongType const &v3;
It is a pity that this still does not work with clang-format in 2021,
even though there was a fix available in 2016. IMHO right pointer alignment
is the default case in C, because syntactically the pointer belongs to the
variable.
See
int* a, b, c; // wrong, just the 1st variable is a pointer
vs.
int *a, *b, *c; // right
Prominent example is the Linux kernel coding style.
Some styles argue the left pointer alignment is better and declaration
lists as shown above should be avoided. That's ok, as different projects
can use different styles, but this important style should work too.
I hope that somebody that has a better understanding about the code,
can take over this patch and land it into main.
For now I must maintain this fork to make it working for our projects.
Cheers,
Gerhard.
Differential Revision: https://reviews.llvm.org/D103245
2021-06-03 22:52:55 +08:00
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- Makes ``PointerAligment: Right`` working with ``AlignConsecutiveDeclarations``.
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(Fixes https://llvm.org/PR27353)
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2020-02-14 05:46:33 +08:00
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libclang
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--------
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- ...
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Static Analyzer
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---------------
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- ...
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.. _release-notes-ubsan:
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Undefined Behavior Sanitizer (UBSan)
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------------------------------------
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Core Analysis Improvements
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==========================
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- ...
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New Issues Found
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================
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- ...
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Python Binding Changes
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----------------------
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The following methods have been added:
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- ...
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Significant Known Problems
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==========================
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Additional Information
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======================
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A wide variety of additional information is available on the `Clang web
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page <https://clang.llvm.org/>`_. The web page contains versions of the
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2020-03-23 05:18:40 +08:00
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API documentation which are up-to-date with the Git version of
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2020-02-14 05:46:33 +08:00
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the source code. You can access versions of these documents specific to
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this release by going into the "``clang/docs/``" directory in the Clang
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tree.
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If you have any questions or comments about Clang, please feel free to
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contact us via the `mailing
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list <https://lists.llvm.org/mailman/listinfo/cfe-dev>`_.
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