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========================================
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Clang 10.0.0 (In-Progress) Release Notes
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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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These are in-progress notes for the upcoming Clang 10 release.
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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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frontend, part of the LLVM Compiler Infrastructure, release 10.0.0. Here we
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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 Subversion 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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What's New in Clang 10.0.0?
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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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- ...
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Improvements to Clang's diagnostics
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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- ...
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Non-comprehensive list of changes in this release
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-------------------------------------------------
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- For X86 target, -march=skylake-avx512, -march=icelake-client,
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-march=icelake-server, -march=cascadelake, -march=cooperlake will default to
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not using 512-bit zmm registers in vectorized code unless 512-bit intrinsics
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are used in the source code. 512-bit operations are known to cause the CPUs
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to run at a lower frequency which can impact performance. This behavior can be
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changed by passing -mprefer-vector-width=512 on the command line.
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New Compiler Flags
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------------------
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- ...
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Deprecated Compiler Flags
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-------------------------
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The following options are deprecated and ignored. They will be removed in
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future versions of Clang.
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- -mmpx used to enable the __MPX__ preprocessor define for the Intel MPX
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instructions. There were no MPX intrinsics.
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- -mno-mpx used to disable -mmpx and is the default behavior.
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- ...
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Modified Compiler Flags
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-----------------------
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- ...
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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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- ...
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Windows Support
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---------------
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- ...
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C Language Changes in Clang
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---------------------------
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- ...
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C11 Feature Support
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^^^^^^^^^^^^^^^^^^^
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...
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C++ Language Changes in Clang
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-----------------------------
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- ...
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C++1z Feature Support
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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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- ...
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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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- gcc passes vectors of __int128 in memory on X86-64. Clang historically
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broke the vectors into multiple scalars using two 64-bit values for each
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element. Clang now matches the gcc behavior on Linux and NetBSD. You can
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switch back to old API behavior with flag: -fclang-abi-compat=9.0.
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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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Internal API Changes
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--------------------
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These are major API changes that have happened since the 9.0.0 release of
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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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- libTooling APIs that transfer ownership of `FrontendAction` objects now pass
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them by `unique_ptr`, making the ownership transfer obvious in the type
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system. `FrontendActionFactory::create()` now returns a
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`unique_ptr<FrontendAction>`. `runToolOnCode`, `runToolOnCodeWithArgs`,
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`ToolInvocation::ToolInvocation()` now take a `unique_ptr<FrontendAction>`.
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Build System Changes
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--------------------
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These are major changes to the build system that have happened since the 9.0.0
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release of Clang. Users of the build system should adjust accordingly.
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- In 8.0.0 and below, the install-clang-headers target would install clang's
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resource directory headers. This installation is now performed by the
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install-clang-resource-headers target. Users of the old install-clang-headers
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target should switch to the new install-clang-resource-headers target. The
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install-clang-headers target now installs clang's API headers (corresponding
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to its libraries), which is consistent with the install-llvm-headers target.
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- In 9.0.0 and later Clang added a new target, clang-cpp, which generates a
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shared library comprised of all the clang component libraries and exporting
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the clang C++ APIs. Additionally the build system gained the new
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"CLANG_LINK_CLANG_DYLIB" option, which defaults Off, and when set to On, will
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force clang (and clang-based tools) to link the clang-cpp library instead of
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statically linking clang's components. This option will reduce the size of
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binary distributions at the expense of compiler performance.
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- ...
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AST Matchers
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------------
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- ...
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clang-format
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------------
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- ...
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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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- ...
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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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API documentation which are up-to-date with the Subversion version of
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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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