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========================================
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Clang 14.0.0 (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 14 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 14.0.0. 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 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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What's New in Clang 14.0.0?
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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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- -Wbitwise-instead-of-logical (part of -Wbool-operation) warns about use of bitwise operators with boolean operands which have side effects.
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Non-comprehensive list of changes in this release
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-------------------------------------------------
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- Maximum _ExtInt size was decreased from 16,777,215 bits to 8,388,608 bits.
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Motivation for this was discussed in PR51829.
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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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- ...
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Modified Compiler Flags
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-----------------------
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- Support has been added for the following processors (``-mcpu`` identifiers in parentheses):
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- RISC-V SiFive E20 (``sifive-e20``).
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- RISC-V SiFive E21 (``sifive-e21``).
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- RISC-V SiFive E24 (``sifive-e24``).
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- RISC-V SiFive E34 (``sifive-e34``).
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- RISC-V SiFive S21 (``sifive-s21``).
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- RISC-V SiFive S51 (``sifive-s51``).
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- RISC-V SiFive S54 (``sifive-s54``).
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- RISC-V SiFive S76 (``sifive-s76``).
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- Support has been added for the following architectures (``-march`` identifiers in parentheses):
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- Armv9-A (``armv9-a``).
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- Armv9.1-A (``armv9.1-a``).
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- Armv9.2-A (``armv9.2-a``).
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Removed 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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- Attributes loaded as clang plugins which are sensitive to LangOpts must
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now override ``acceptsLangOpts`` instead of ``diagLangOpts``.
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Returning false will produce a generic "attribute ignored" diagnostic, as
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with clang's built-in attributes.
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If plugins want to provide richer diagnostics, they can do so when the
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attribute is handled instead, e.g. in ``handleDeclAttribute``.
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(This was changed in order to better support attributes in code completion).
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- __has_cpp_attribute, __has_c_attribute, __has_attribute, and __has_declspec
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will now macro expand their argument. This causes a change in behavior for
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code using ``__has_cpp_attribute(__clang__::attr)`` (and same for
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``__has_c_attribute``) where it would previously expand to ``0`` for all
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attributes, but will now issue an error due to the expansion of the
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predefined ``__clang__`` macro.
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Windows Support
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---------------
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- An MSVC compatibility workaround for C++ operator names was removed. As a
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result, the ``<query.h>`` Windows SDK header may not compile out of the box.
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Users should use a recent SDK and pass ``-DQUERY_H_RESTRICTION_PERMISSIVE``
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or pass ``/permissive`` to disable C++ operator names altogether. See
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`PR42427 <https://llvm.org/pr42427>` for more info.
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C Language Changes in Clang
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---------------------------
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- The value of ``__STDC_VERSION__`` has been bumped to ``202000L`` when passing
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``-std=c2x`` so that it can be distinguished from C17 mode. This value is
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expected to change again when C23 is published.
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- Wide multi-characters literals such as ``L'ab'`` that would previously be interpreted as ``L'b'``
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are now ill-formed in all language modes. The motivation for this change is outlined in
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`P2362 <wg21.link/P2362>`_.
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- Support for ``__attribute__((error("")))`` and
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``__attribute__((warning("")))`` function attributes have been added.
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- The maximum allowed alignment has been increased from 2^29 to 2^32.
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C++ Language Changes in Clang
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-----------------------------
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- ...
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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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^^^^^^^^^^^^^^^^^^^^^
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- Implemented `P1938R3: if consteval <https://wg21.link/P1938R3>`_.
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- Implemented `P2360R0: Extend init-statement to allow alias-declaration <https://wg21.link/P2360R0>`_.
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CUDA Language Changes in Clang
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------------------------------
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- Clang now supports CUDA versions up to 11.4.
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- Default GPU architecture has been changed from sm_20 to sm_35.
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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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- ``clang-nvlink-wrapper`` tool introduced to support linking of cubin files archived in an archive. See :doc:`ClangNvlinkWrapper`.
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CUDA Support in Clang
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---------------------
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- ...
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X86 Support in Clang
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--------------------
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- Support for ``AVX512-FP16`` instructions has been added.
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Arm and AArch64 Support in Clang
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--------------------------------
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- Support has been added for the following processors (command-line identifiers in parentheses):
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- Arm Cortex-A510 (``cortex-a510``)
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- The -mtune flag is no longer ignored for AArch64. It is now possible to
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tune code generation for a particular CPU with -mtune without setting any
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architectural features. For example, compiling with
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"-mcpu=generic -mtune=cortex-a57" will not enable any Cortex-A57 specific
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architecture features, but will enable certain optimizations specific to
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Cortex-A57 CPUs and enable the use of a more accurate scheduling model.
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Internal API Changes
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--------------------
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- ...
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Build System Changes
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--------------------
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- ...
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AST Matchers
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------------
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- ``TypeLoc`` AST Matchers are now available. These matchers provide helpful
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utilities for matching ``TypeLoc`` nodes, such as the ``pointerTypeLoc``
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matcher or the ``hasReturnTypeLoc`` matcher. The addition of these matchers
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was made possible by changes to the handling of ``TypeLoc`` nodes that
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allows them to enjoy the same static type checking as other AST node kinds.
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clang-format
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------------
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- Option ``AllowShortEnumsOnASingleLine: false`` has been improved, it now
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correctly places the opening brace according to ``BraceWrapping.AfterEnum``.
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- Option ``QualifierAligment`` has been added in order to auto-arrange the
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positioning of specifiers/qualifiers
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`const` `volatile` `static` `inline` `constexpr` `restrict`
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in variable and parameter declarations to be either ``Right`` aligned
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or ``Left`` aligned or ``Custom`` using ``QualifierOrder``.
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- Option ``QualifierOrder`` has been added to allow the order
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`const` `volatile` `static` `inline` `constexpr` `restrict`
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to be controlled relative to the `type`.
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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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API documentation which are up-to-date with the Git 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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