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========================================
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Clang 11.0.0 (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 11 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 11.0.0. 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 11.0.0?
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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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- -Wpointer-to-int-cast is a new warning group. This group warns about C-style
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casts of pointers to a integer type too small to hold all possible values.
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Non-comprehensive list of changes in this release
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-------------------------------------------------
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New Compiler Flags
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------------------
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- -fstack-clash-protection will provide a protection against the stack clash
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attack for x86 architecture through automatic probing of each page of
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allocated stack.
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- -ffp-exception-behavior={ignore,maytrap,strict} allows the user to specify
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the floating-point exception behavior. The default setting is ``ignore``.
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- -ffp-model={precise,strict,fast} provides the user an umbrella option to
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simplify access to the many single purpose floating point options. The default
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setting is ``precise``.
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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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- ...
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Modified Compiler Flags
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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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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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- Clang now implements a restriction on giving non-C-compatible anonymous
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structs a typedef name for linkage purposes, as described in C++ committee
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paper `P1766R1 <http://wg21.link/p1766r1>`. This paper was adopted by the
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C++ committee as a Defect Report resolution, so it is applied retroactively
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to all C++ standard versions. This affects code such as:
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.. code-block:: c++
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typedef struct {
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int f() { return 0; }
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} S;
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Previous versions of Clang rejected some constructs of this form
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(specifically, where the linkage of the type happened to be computed
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before the parser reached the typedef name); those cases are still rejected
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in Clang 11. In addition, cases that previous versions of Clang did not
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reject now produce an extension warning. This warning can be disabled with
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the warning flag ``-Wno-non-c-typedef-for-linkage``.
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Affected code should be updated to provide a tag name for the anonymous
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struct:
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.. code-block:: c++
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struct S {
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int f() { return 0; }
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};
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If the code is shared with a C compilation (for example, if the parts that
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are not C-compatible are guarded with ``#ifdef __cplusplus``), the typedef
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declaration should be retained, but a tag name should still be provided:
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.. code-block:: c++
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typedef struct S {
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int f() { return 0; }
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} S;
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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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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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Internal API Changes
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--------------------
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These are major API changes that have happened since the 10.0.0 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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Build System Changes
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--------------------
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These are major changes to the build system that have happened since the 10.0.0
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release of Clang. Users of the build system should adjust accordingly.
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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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- Option ``IndentCaseBlocks`` has been added to support treating the block
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following a switch case label as a scope block which gets indented itself.
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It helps avoid having the closing bracket align with the switch statement's
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closing bracket (when ``IndentCaseLabels`` is ``false``).
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- Option ``ObjCBreakBeforeNestedBlockParam`` has been added to optionally apply
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linebreaks for function arguments declarations before nested blocks.
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.. code-block:: c++
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switch (fool) { vs. switch (fool) {
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case 1: case 1: {
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{ bar();
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bar(); } break;
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} default: {
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break; plop();
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default: }
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{ }
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plop();
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}
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}
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- Option ``InsertTrailingCommas`` can be set to ``TCS_Wrapped`` to insert
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trailing commas in container literals (arrays and objects) that wrap across
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multiple lines. It is currently only available for JavaScript and disabled by
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default (``TCS_None``).
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- Option ``BraceWrapping.BeforeLambdaBody`` has been added to manage lambda
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line break inside function parameter call in Allman style.
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.. code-block:: c++
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true:
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connect(
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[]()
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{
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foo();
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bar();
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});
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false:
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connect([]() {
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foo();
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bar();
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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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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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