29992cfd62
This patch adds a human readable trap category and message to UBSan traps. The category and message are encoded in a fake frame in the debug info where the function is a fake inline function where the name encodes the trap category and message. This is the same mechanism used by Clang’s `__builtin_verbose_trap()`. This change allows consumers of binaries built with trapping UBSan to more easily identify the reason for trapping. In particular LLDB already has a frame recognizer that recognizes the fake function names emitted in debug info by this patch. A patch testing this behavior in LLDB will be added in a separately. The human readable trap messages are based on the messages currently emitted by the userspace runtime for UBSan in compiler-rt. Note the wording is not identical because the userspace UBSan runtime has access to dynamic information that is not available during Clang’s codegen. Test cases for each UBSan trap kind are included. This complements the [`-fsanitize-annotate-debug-info` feature](https://github.com/llvm/llvm-project/pull/141997). While `-fsanitize-annotate-debug-info` attempts to annotate all UBSan-added instructions, this feature (`-fsanitize-debug-trap-reasons`) only annotates the final trap instruction using SanitizerHandler information. This work is part of a GSoc 2025 project.
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===========================================
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Clang |release| |ReleaseNotesTitle|
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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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.. only:: PreRelease
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.. warning::
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These are in-progress notes for the upcoming Clang |version| release.
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Release notes for previous releases can be found on
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`the Releases Page <https://llvm.org/releases/>`_.
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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 |release|. 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>`_. For the libc++ release notes,
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see `this page <https://libcxx.llvm.org/ReleaseNotes.html>`_. All LLVM releases
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may be downloaded from the `LLVM releases web 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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Potentially Breaking Changes
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============================
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C/C++ Language Potentially Breaking Changes
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-------------------------------------------
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C++ Specific Potentially Breaking Changes
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-----------------------------------------
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- For C++20 modules, the Reduced BMI mode will be the default option. This may introduce
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regressions if your build system supports two-phase compilation model but haven't support
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reduced BMI or it is a compiler bug or a bug in users code.
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ABI Changes in This Version
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---------------------------
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AST Dumping Potentially Breaking Changes
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----------------------------------------
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Clang Frontend Potentially Breaking Changes
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-------------------------------------------
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Clang Python Bindings Potentially Breaking Changes
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--------------------------------------------------
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What's New in Clang |release|?
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==============================
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C++ Language Changes
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--------------------
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C++2c Feature Support
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^^^^^^^^^^^^^^^^^^^^^
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C++23 Feature Support
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^^^^^^^^^^^^^^^^^^^^^
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C++20 Feature Support
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^^^^^^^^^^^^^^^^^^^^^
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C++17 Feature Support
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^^^^^^^^^^^^^^^^^^^^^
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Resolutions to C++ Defect Reports
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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C Language Changes
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------------------
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C2y Feature Support
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^^^^^^^^^^^^^^^^^^^
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C23 Feature Support
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^^^^^^^^^^^^^^^^^^^
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Non-comprehensive list of changes in this release
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-------------------------------------------------
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- Added ``__builtin_elementwise_minnumnum`` and ``__builtin_elementwise_maxnumnum``.
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- Trapping UBSan (e.g. ``-fsanitize-trap=undefined``) now emits a string describing the reason for
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trapping into the generated debug info. This feature allows debuggers (e.g. LLDB) to display
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the reason for trapping if the trap is reached. The string is currently encoded in the debug
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info as an artificial frame that claims to be inlined at the trap location. The function used
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for the artificial frame is an artificial function whose name encodes the reason for trapping.
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The encoding used is currently the same as ``__builtin_verbose_trap`` but might change in the future.
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This feature is enabled by default but can be disabled by compiling with
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``-fno-sanitize-annotate-debug-info-traps``.
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New Compiler Flags
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------------------
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- New option ``-fno-sanitize-annotate-debug-info-traps`` added to disable emitting trap reasons into the debug info when compiling with trapping UBSan (e.g. ``-fsanitize-trap=undefined``).
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Deprecated Compiler Flags
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-------------------------
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Modified Compiler Flags
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-----------------------
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Removed Compiler Flags
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-------------------------
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Attribute Changes in Clang
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--------------------------
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Improvements to Clang's diagnostics
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-----------------------------------
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- Added a separate diagnostic group ``-Wfunction-effect-redeclarations``, for the more pedantic
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diagnostics for function effects (``[[clang::nonblocking]]`` and ``[[clang::nonallocating]]``).
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Moved the warning for a missing (though implied) attribute on a redeclaration into this group.
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Added a new warning in this group for the case where the attribute is missing/implicit on
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an override of a virtual method.
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Improvements to Clang's time-trace
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----------------------------------
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Improvements to Coverage Mapping
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--------------------------------
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Bug Fixes in This Version
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-------------------------
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- Fix a crash when marco name is empty in ``#pragma push_macro("")`` or
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``#pragma pop_macro("")``. (#GH149762).
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Bug Fixes to Compiler Builtins
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Bug Fixes to Attribute Support
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Bug Fixes to C++ Support
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^^^^^^^^^^^^^^^^^^^^^^^^
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- Diagnose binding a reference to ``*nullptr`` during constant evaluation. (#GH48665)
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- Suppress ``-Wdeprecated-declarations`` in implicitly generated functions. (#GH147293)
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- Fix a crash when deleting a pointer to an incomplete array (#GH150359).
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Bug Fixes to AST Handling
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^^^^^^^^^^^^^^^^^^^^^^^^^
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Miscellaneous Bug Fixes
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^^^^^^^^^^^^^^^^^^^^^^^
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Miscellaneous Clang Crashes Fixed
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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OpenACC Specific Changes
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------------------------
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Target Specific Changes
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-----------------------
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AMDGPU Support
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^^^^^^^^^^^^^^
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NVPTX Support
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^^^^^^^^^^^^^^
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X86 Support
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^^^^^^^^^^^
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Arm and AArch64 Support
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^^^^^^^^^^^^^^^^^^^^^^^
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Android Support
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^^^^^^^^^^^^^^^
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Windows Support
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^^^^^^^^^^^^^^^
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LoongArch Support
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^^^^^^^^^^^^^^^^^
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RISC-V Support
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^^^^^^^^^^^^^^
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CUDA/HIP Language Changes
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^^^^^^^^^^^^^^^^^^^^^^^^^
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CUDA Support
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^^^^^^^^^^^^
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AIX Support
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^^^^^^^^^^^
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NetBSD Support
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^^^^^^^^^^^^^^
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WebAssembly Support
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^^^^^^^^^^^^^^^^^^^
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AVR Support
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^^^^^^^^^^^
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DWARF Support in Clang
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----------------------
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Floating Point Support in Clang
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-------------------------------
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Fixed Point Support in Clang
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----------------------------
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AST Matchers
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------------
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- Ensure ``hasBitWidth`` doesn't crash on bit widths that are dependent on template
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parameters.
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clang-format
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------------
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libclang
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--------
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Code Completion
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---------------
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Static Analyzer
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---------------
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- The Clang Static Analyzer now handles parenthesized initialization.
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(#GH148875)
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New features
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^^^^^^^^^^^^
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Crash and bug fixes
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^^^^^^^^^^^^^^^^^^^
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Improvements
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^^^^^^^^^^^^
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Moved checkers
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^^^^^^^^^^^^^^
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.. _release-notes-sanitizers:
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Sanitizers
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----------
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Python Binding Changes
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----------------------
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OpenMP Support
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--------------
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- Added parsing and semantic analysis support for the ``need_device_addr``
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modifier in the ``adjust_args`` clause.
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- Allow array length to be omitted in array section subscript expression.
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Improvements
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^^^^^^^^^^^^
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Additional Information
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======================
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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
|
|
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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|
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If you have any questions or comments about Clang, please feel free to
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contact us on the `Discourse forums (Clang Frontend category)
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<https://discourse.llvm.org/c/clang/6>`_.
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