clang/docs/ReleaseNotes.rst - llvm-project - Git at Google

 ========================================
 Clang 14.0.0 (In-Progress) Release Notes
 ========================================

 .. contents::
    :local:
    :depth: 2

 Written by the `LLVM Team <https://llvm.org/>`_

 .. warning::

    These are in-progress notes for the upcoming Clang 14 release.
    Release notes for previous releases can be found on
    `the Download Page <https://releases.llvm.org/download.html>`_.

 Introduction
 ============

 This document contains the release notes for the Clang C/C++/Objective-C
 frontend, part of the LLVM Compiler Infrastructure, release 14.0.0. Here we
 describe the status of Clang in some detail, including major
 improvements from the previous release and new feature work. For the
 general LLVM release notes, see `the LLVM
 documentation <https://llvm.org/docs/ReleaseNotes.html>`_. All LLVM
 releases may be downloaded from the `LLVM releases web
 site <https://llvm.org/releases/>`_.

 For more information about Clang or LLVM, including information about the
 latest release, please see the `Clang Web Site <https://clang.llvm.org>`_ or the
 `LLVM Web Site <https://llvm.org>`_.

 Note that if you are reading this file from a Git checkout or the
 main Clang web page, this document applies to the *next* release, not
 the current one. To see the release notes for a specific release, please
 see the `releases page <https://llvm.org/releases/>`_.

 What's New in Clang 14.0.0?
 ===========================

 Some of the major new features and improvements to Clang are listed
 here. Generic improvements to Clang as a whole or to its underlying
 infrastructure are described first, followed by language-specific
 sections with improvements to Clang's support for those languages.

 Major New Features
 ------------------

 -  ...

 Improvements to Clang's diagnostics
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 - -Wbitwise-instead-of-logical (part of -Wbool-operation) warns about use of bitwise operators with boolean operands which have side effects.

 Non-comprehensive list of changes in this release
 -------------------------------------------------

 - Maximum _ExtInt size was decreased from 16,777,215 bits to 8,388,608 bits.
   Motivation for this was discussed in PR51829.

 New Compiler Flags
 ------------------

 - Clang plugin arguments can now be passed through the compiler driver via
   ``-fplugin-arg-pluginname-arg``, similar to GCC's ``-fplugin-arg``.

 Deprecated Compiler Flags
 -------------------------

 - -Wweak-template-vtables has been deprecated and no longer has any effect. The
   flag will be removed in the next release.

 Modified Compiler Flags
 -----------------------

 - Support has been added for the following processors (``-mcpu`` identifiers in parentheses):

   - RISC-V SiFive E20 (``sifive-e20``).
   - RISC-V SiFive E21 (``sifive-e21``).
   - RISC-V SiFive E24 (``sifive-e24``).
   - RISC-V SiFive E34 (``sifive-e34``).
   - RISC-V SiFive S21 (``sifive-s21``).
   - RISC-V SiFive S51 (``sifive-s51``).
   - RISC-V SiFive S54 (``sifive-s54``).
   - RISC-V SiFive S76 (``sifive-s76``).

 - Support has been added for the following architectures (``-march`` identifiers in parentheses):

   - Armv9-A (``armv9-a``).
   - Armv9.1-A (``armv9.1-a``).
   - Armv9.2-A (``armv9.2-a``).

 Removed Compiler Flags
 -------------------------

 - ...

 New Pragmas in Clang
 --------------------

 - ...

 Attribute Changes in Clang
 --------------------------

 - Attributes loaded as clang plugins which are sensitive to LangOpts must
   now override ``acceptsLangOpts`` instead of ``diagLangOpts``.
   Returning false will produce a generic "attribute ignored" diagnostic, as
   with clang's built-in attributes.
   If plugins want to provide richer diagnostics, they can do so when the
   attribute is handled instead, e.g. in ``handleDeclAttribute``.
   (This was changed in order to better support attributes in code completion).

 - __has_cpp_attribute, __has_c_attribute, __has_attribute, and __has_declspec
   will now macro expand their argument. This causes a change in behavior for
   code using ``__has_cpp_attribute(__clang__::attr)`` (and same for
   ``__has_c_attribute``) where it would previously expand to ``0`` for all
   attributes, but will now issue an error due to the expansion of the
   predefined ``__clang__`` macro.

 Windows Support
 ---------------

 - An MSVC compatibility workaround for C++ operator names was removed. As a
   result, the ``<query.h>`` Windows SDK header may not compile out of the box.
   Users should use a recent SDK and pass ``-DQUERY_H_RESTRICTION_PERMISSIVE``
   or pass ``/permissive`` to disable C++ operator names altogether. See
   `PR42427 <https://llvm.org/pr42427>` for more info.

 C Language Changes in Clang
 ---------------------------

 - The value of ``__STDC_VERSION__`` has been bumped to ``202000L`` when passing
   ``-std=c2x`` so that it can be distinguished from C17 mode. This value is
   expected to change again when C23 is published.
 - Wide multi-characters literals such as ``L'ab'`` that would previously be interpreted as ``L'b'``
   are now ill-formed in all language modes. The motivation for this change is outlined in
   `P2362 <wg21.link/P2362>`_.
 - Support for ``__attribute__((error("")))`` and
   ``__attribute__((warning("")))`` function attributes have been added.
 - The maximum allowed alignment has been increased from 2^29 to 2^32.

 C++ Language Changes in Clang
 -----------------------------

 - ...

 C++20 Feature Support
 ^^^^^^^^^^^^^^^^^^^^^
 ...

 C++2b Feature Support
 ^^^^^^^^^^^^^^^^^^^^^
 - Implemented `P1938R3: if consteval <https://wg21.link/P1938R3>`_.
 - Implemented `P2360R0: Extend init-statement to allow alias-declaration <https://wg21.link/P2360R0>`_.


 CUDA Language Changes in Clang
 ------------------------------

 - Clang now supports CUDA versions up to 11.5.
 - Default GPU architecture has been changed from sm_20 to sm_35.

 Objective-C Language Changes in Clang
 -------------------------------------

 OpenCL C Language Changes in Clang
 ----------------------------------

 ...

 ABI Changes in Clang
 --------------------

 OpenMP Support in Clang
 -----------------------

 - ``clang-nvlink-wrapper`` tool introduced to support linking of cubin files archived in an archive. See :doc:`ClangNvlinkWrapper`.


 CUDA Support in Clang
 ---------------------

 - ...

 X86 Support in Clang
 --------------------

 - Support for ``AVX512-FP16`` instructions has been added.

 Arm and AArch64 Support in Clang
 --------------------------------

 - Support has been added for the following processors (command-line identifiers in parentheses):
   - Arm Cortex-A510 (``cortex-a510``)
   - Arm Cortex-X2 (``cortex-x2``)
   - Arm Cortex-A710 (``cortex-A710``)

 - The -mtune flag is no longer ignored for AArch64. It is now possible to
   tune code generation for a particular CPU with -mtune without setting any
   architectural features. For example, compiling with
   "-mcpu=generic -mtune=cortex-a57" will not enable any Cortex-A57 specific
   architecture features, but will enable certain optimizations specific to
   Cortex-A57 CPUs and enable the use of a more accurate scheduling model.


 Floating Point Support in Clang
 -------------------------------
 - The default setting of FP contraction (FMA) is now -ffp-contract=on (for
   languages other than CUDA/HIP) even when optimization is off. Previously,
   the default behavior was equivalent to -ffp-contract=off (-ffp-contract
   was not set).
   Related to this, the switch -ffp-model=precise now implies -ffp-contract=on
   rather than -ffp-contract=fast, and the documentation of these features has
   been clarified. Previously, the documentation claimed that -ffp-model=precise
   was the default, but this was incorrect because the precise model implied
   -ffp-contract=fast, wheras the (now corrected) default behavior is
   -ffp-contract=on.
   -ffp-model=precise is now exactly the default mode of the compiler.

 Internal API Changes
 --------------------

 - ...

 Build System Changes
 --------------------

 - ...

 AST Matchers
 ------------

 - ``TypeLoc`` AST Matchers are now available. These matchers provide helpful
   utilities for matching ``TypeLoc`` nodes, such as the ``pointerTypeLoc``
   matcher or the ``hasReturnTypeLoc`` matcher. The addition of these matchers
   was made possible by changes to the handling of ``TypeLoc`` nodes that
   allows them to enjoy the same static type checking as other AST node kinds.
 - ``LambdaCapture`` AST Matchers are now available. These matchers allow for
   the binding of ``LambdaCapture`` nodes. The ``LambdaCapture`` matchers added
   include the ``lambdaCapture`` node matcher, the ``capturesVar`` traversal
   matcher, and ``capturesThis`` narrowing matcher.
 - The ``hasAnyCapture`` matcher now only accepts an inner matcher of type
   ``Matcher<LambdaCapture>``. The matcher originally accepted an inner matcher
   of type ``Matcher<CXXThisExpr>`` or ``Matcher<VarDecl>``.

 clang-format
 ------------

 - Option ``AllowShortEnumsOnASingleLine: false`` has been improved, it now
   correctly places the opening brace according to ``BraceWrapping.AfterEnum``.

 - Option ``QualifierAligment`` has been added in order to auto-arrange the
   positioning of specifiers/qualifiers
   `const` `volatile` `static` `inline` `constexpr` `restrict`
   in variable and parameter declarations to be either ``Right`` aligned
   or ``Left`` aligned or ``Custom`` using ``QualifierOrder``.

 - Option ``QualifierOrder`` has been added to allow the order
   `const` `volatile` `static` `inline` `constexpr` `restrict`
   to be controlled relative to the `type`.

 - Add a ``Custom`` style to ``SpaceBeforeParens``, to better configure the
   space before parentheses. The custom options can be set using
   ``SpaceBeforeParensOptions``.

 - Improved Cpp20 Modules support.

 libclang
 --------

 - ...

 Static Analyzer
 ---------------

 - ...

 .. _release-notes-ubsan:

 Undefined Behavior Sanitizer (UBSan)
 ------------------------------------

 Core Analysis Improvements
 ==========================

 - ...

 New Issues Found
 ================

 - ...

 Python Binding Changes
 ----------------------

 The following methods have been added:

 -  ...

 Significant Known Problems
 ==========================

 Additional Information
 ======================

 A wide variety of additional information is available on the `Clang web
 page <https://clang.llvm.org/>`_. The web page contains versions of the
 API documentation which are up-to-date with the Git version of
 the source code. You can access versions of these documents specific to
 this release by going into the "``clang/docs/``" directory in the Clang
 tree.

 If you have any questions or comments about Clang, please feel free to
 contact us via the `mailing
 list <https://lists.llvm.org/mailman/listinfo/cfe-dev>`_.
	========================================
	Clang 14.0.0 (In-Progress) Release Notes
	========================================

	.. contents::
	:local:
	:depth: 2

	Written by the `LLVM Team <https://llvm.org/>`_

	.. warning::

	These are in-progress notes for the upcoming Clang 14 release.
	Release notes for previous releases can be found on
	`the Download Page <https://releases.llvm.org/download.html>`_.

	Introduction
	============

	This document contains the release notes for the Clang C/C++/Objective-C
	frontend, part of the LLVM Compiler Infrastructure, release 14.0.0. Here we
	describe the status of Clang in some detail, including major
	improvements from the previous release and new feature work. For the
	general LLVM release notes, see `the LLVM
	documentation <https://llvm.org/docs/ReleaseNotes.html>`_. All LLVM
	releases may be downloaded from the `LLVM releases web
	site <https://llvm.org/releases/>`_.

	For more information about Clang or LLVM, including information about the
	latest release, please see the `Clang Web Site <https://clang.llvm.org>`_ or the
	`LLVM Web Site <https://llvm.org>`_.

	Note that if you are reading this file from a Git checkout or the
	main Clang web page, this document applies to the next release, not
	the current one. To see the release notes for a specific release, please
	see the `releases page <https://llvm.org/releases/>`_.

	What's New in Clang 14.0.0?
	===========================

	Some of the major new features and improvements to Clang are listed
	here. Generic improvements to Clang as a whole or to its underlying
	infrastructure are described first, followed by language-specific
	sections with improvements to Clang's support for those languages.

	Major New Features
	------------------

	- ...

	Improvements to Clang's diagnostics
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

	- -Wbitwise-instead-of-logical (part of -Wbool-operation) warns about use of bitwise operators with boolean operands which have side effects.

	Non-comprehensive list of changes in this release
	-------------------------------------------------

	- Maximum _ExtInt size was decreased from 16,777,215 bits to 8,388,608 bits.
	Motivation for this was discussed in PR51829.

	New Compiler Flags
	------------------

	- Clang plugin arguments can now be passed through the compiler driver via
	``-fplugin-arg-pluginname-arg``, similar to GCC's ``-fplugin-arg``.

	Deprecated Compiler Flags
	-------------------------

	- -Wweak-template-vtables has been deprecated and no longer has any effect. The
	flag will be removed in the next release.

	Modified Compiler Flags
	-----------------------

	- Support has been added for the following processors (``-mcpu`` identifiers in parentheses):

	- RISC-V SiFive E20 (``sifive-e20``).
	- RISC-V SiFive E21 (``sifive-e21``).
	- RISC-V SiFive E24 (``sifive-e24``).
	- RISC-V SiFive E34 (``sifive-e34``).
	- RISC-V SiFive S21 (``sifive-s21``).
	- RISC-V SiFive S51 (``sifive-s51``).
	- RISC-V SiFive S54 (``sifive-s54``).
	- RISC-V SiFive S76 (``sifive-s76``).

	- Support has been added for the following architectures (``-march`` identifiers in parentheses):

	- Armv9-A (``armv9-a``).
	- Armv9.1-A (``armv9.1-a``).
	- Armv9.2-A (``armv9.2-a``).

	Removed Compiler Flags
	-------------------------

	- ...

	New Pragmas in Clang
	--------------------

	- ...

	Attribute Changes in Clang
	--------------------------

	- Attributes loaded as clang plugins which are sensitive to LangOpts must
	now override ``acceptsLangOpts`` instead of ``diagLangOpts``.
	Returning false will produce a generic "attribute ignored" diagnostic, as
	with clang's built-in attributes.
	If plugins want to provide richer diagnostics, they can do so when the
	attribute is handled instead, e.g. in ``handleDeclAttribute``.
	(This was changed in order to better support attributes in code completion).

	- __has_cpp_attribute, __has_c_attribute, __has_attribute, and __has_declspec
	will now macro expand their argument. This causes a change in behavior for
	code using ``__has_cpp_attribute(__clang__::attr)`` (and same for
	``__has_c_attribute``) where it would previously expand to ``0`` for all
	attributes, but will now issue an error due to the expansion of the
	predefined ``__clang__`` macro.

	Windows Support
	---------------

	- An MSVC compatibility workaround for C++ operator names was removed. As a
	result, the ``<query.h>`` Windows SDK header may not compile out of the box.
	Users should use a recent SDK and pass ``-DQUERY_H_RESTRICTION_PERMISSIVE``
	or pass ``/permissive`` to disable C++ operator names altogether. See
	`PR42427 <https://llvm.org/pr42427>` for more info.

	C Language Changes in Clang
	---------------------------

	- The value of ``__STDC_VERSION__`` has been bumped to ``202000L`` when passing
	``-std=c2x`` so that it can be distinguished from C17 mode. This value is
	expected to change again when C23 is published.
	- Wide multi-characters literals such as ``L'ab'`` that would previously be interpreted as ``L'b'``
	are now ill-formed in all language modes. The motivation for this change is outlined in
	`P2362 <wg21.link/P2362>`_.
	- Support for ``__attribute__((error("")))`` and
	``__attribute__((warning("")))`` function attributes have been added.
	- The maximum allowed alignment has been increased from 2^29 to 2^32.

	C++ Language Changes in Clang
	-----------------------------

	- ...

	C++20 Feature Support
	^^^^^^^^^^^^^^^^^^^^^
	...

	C++2b Feature Support
	^^^^^^^^^^^^^^^^^^^^^
	- Implemented `P1938R3: if consteval <https://wg21.link/P1938R3>`_.
	- Implemented `P2360R0: Extend init-statement to allow alias-declaration <https://wg21.link/P2360R0>`_.


	CUDA Language Changes in Clang
	------------------------------

	- Clang now supports CUDA versions up to 11.5.
	- Default GPU architecture has been changed from sm_20 to sm_35.

	Objective-C Language Changes in Clang
	-------------------------------------

	OpenCL C Language Changes in Clang
	----------------------------------

	...

	ABI Changes in Clang
	--------------------

	OpenMP Support in Clang
	-----------------------

	- ``clang-nvlink-wrapper`` tool introduced to support linking of cubin files archived in an archive. See :doc:`ClangNvlinkWrapper`.


	CUDA Support in Clang
	---------------------

	- ...

	X86 Support in Clang
	--------------------

	- Support for ``AVX512-FP16`` instructions has been added.

	Arm and AArch64 Support in Clang
	--------------------------------

	- Support has been added for the following processors (command-line identifiers in parentheses):
	- Arm Cortex-A510 (``cortex-a510``)
	- Arm Cortex-X2 (``cortex-x2``)
	- Arm Cortex-A710 (``cortex-A710``)

	- The -mtune flag is no longer ignored for AArch64. It is now possible to
	tune code generation for a particular CPU with -mtune without setting any
	architectural features. For example, compiling with
	"-mcpu=generic -mtune=cortex-a57" will not enable any Cortex-A57 specific
	architecture features, but will enable certain optimizations specific to
	Cortex-A57 CPUs and enable the use of a more accurate scheduling model.


	Floating Point Support in Clang
	-------------------------------
	- The default setting of FP contraction (FMA) is now -ffp-contract=on (for
	languages other than CUDA/HIP) even when optimization is off. Previously,
	the default behavior was equivalent to -ffp-contract=off (-ffp-contract
	was not set).
	Related to this, the switch -ffp-model=precise now implies -ffp-contract=on
	rather than -ffp-contract=fast, and the documentation of these features has
	been clarified. Previously, the documentation claimed that -ffp-model=precise
	was the default, but this was incorrect because the precise model implied
	-ffp-contract=fast, wheras the (now corrected) default behavior is
	-ffp-contract=on.
	-ffp-model=precise is now exactly the default mode of the compiler.

	Internal API Changes
	--------------------

	- ...

	Build System Changes
	--------------------

	- ...

	AST Matchers
	------------

	- ``TypeLoc`` AST Matchers are now available. These matchers provide helpful
	utilities for matching ``TypeLoc`` nodes, such as the ``pointerTypeLoc``
	matcher or the ``hasReturnTypeLoc`` matcher. The addition of these matchers
	was made possible by changes to the handling of ``TypeLoc`` nodes that
	allows them to enjoy the same static type checking as other AST node kinds.
	- ``LambdaCapture`` AST Matchers are now available. These matchers allow for
	the binding of ``LambdaCapture`` nodes. The ``LambdaCapture`` matchers added
	include the ``lambdaCapture`` node matcher, the ``capturesVar`` traversal
	matcher, and ``capturesThis`` narrowing matcher.
	- The ``hasAnyCapture`` matcher now only accepts an inner matcher of type
	``Matcher<LambdaCapture>``. The matcher originally accepted an inner matcher
	of type ``Matcher<CXXThisExpr>`` or ``Matcher<VarDecl>``.

	clang-format
	------------

	- Option ``AllowShortEnumsOnASingleLine: false`` has been improved, it now
	correctly places the opening brace according to ``BraceWrapping.AfterEnum``.

	- Option ``QualifierAligment`` has been added in order to auto-arrange the
	positioning of specifiers/qualifiers
	`const` `volatile` `static` `inline` `constexpr` `restrict`
	in variable and parameter declarations to be either ``Right`` aligned
	or ``Left`` aligned or ``Custom`` using ``QualifierOrder``.

	- Option ``QualifierOrder`` has been added to allow the order
	`const` `volatile` `static` `inline` `constexpr` `restrict`
	to be controlled relative to the `type`.

	- Add a ``Custom`` style to ``SpaceBeforeParens``, to better configure the
	space before parentheses. The custom options can be set using
	``SpaceBeforeParensOptions``.

	- Improved Cpp20 Modules support.

	libclang
	--------

	- ...

	Static Analyzer
	---------------

	- ...

	.. _release-notes-ubsan:

	Undefined Behavior Sanitizer (UBSan)
	------------------------------------

	Core Analysis Improvements
	==========================

	- ...

	New Issues Found
	================

	- ...

	Python Binding Changes
	----------------------

	The following methods have been added:

	- ...

	Significant Known Problems
	==========================

	Additional Information
	======================

	A wide variety of additional information is available on the `Clang web
	page <https://clang.llvm.org/>`_. The web page contains versions of the
	API documentation which are up-to-date with the Git version of
	the source code. You can access versions of these documents specific to
	this release by going into the "``clang/docs/``" directory in the Clang
	tree.

	If you have any questions or comments about Clang, please feel free to
	contact us via the `mailing
	list <https://lists.llvm.org/mailman/listinfo/cfe-dev>`_.