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

 ========================================
 Clang 11.0.0 (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 11 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 11.0.0. 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 11.0.0?
 ===========================

 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
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 - -Wpointer-to-int-cast is a new warning group. This group warns about C-style
   casts of pointers to a integer type too small to hold all possible values.

 - -Wuninitialized-const-reference is a new warning controlled by
   -Wuninitialized. It warns on cases where uninitialized variables are passed
   as const reference arguments to a function.

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

 - For the ARM target, C-language intrinsics are now provided for the full Arm
   v8.1-M MVE instruction set. ``<arm_mve.h>`` supports the complete API defined
   in the Arm C Language Extensions.

 - For the ARM target, C-language intrinsics ``<arm_cde.h>`` for the CDE
   instruction set are now provided.

 - clang adds support for a set of  extended integer types (``_ExtInt(N)``) that
   permit non-power of 2 integers, exposing the LLVM integer types. Since a major
   motivating use case for these types is to limit 'bit' usage, these types don't
   automatically promote to 'int' when operations are done between two
   ``ExtInt(N)`` types, instead math occurs at the size of the largest
   ``ExtInt(N)`` type.

 - Users of UBSan, PGO, and coverage on Windows will now need to add clang's
   library resource directory to their library search path. These features all
   use runtime libraries, and Clang provides these libraries in its resource
   directory. For example, if LLVM is installed in ``C:\Program Files\LLVM``,
   then the profile runtime library will appear at
   ``C:\Program Files\LLVM\lib\clang\11.0.0\lib\windows\clang_rt.profile-x86_64.lib``.
   To ensure that the linker can find the appropriate library, users should pass
   ``/LIBPATH:C:\Program Files\LLVM\lib\clang\11.0.0\lib\windows`` to the
   linker. If the user links the program with the ``clang`` or ``clang-cl``
   drivers, the driver will pass this flag for them.

 - Clang's profile files generated through ``-fprofile-instr-generate`` are using
   a fixed hashing algorithm that prevents some collision when loading
   out-of-date profile informations. Clang can still read old profile files.

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

 - -fstack-clash-protection will provide a protection against the stack clash
   attack for x86, s390x and ppc64 architectures through automatic probing of
   each page of allocated stack.

 - -ffp-exception-behavior={ignore,maytrap,strict} allows the user to specify
   the floating-point exception behavior. The default setting is ``ignore``.

 - -ffp-model={precise,strict,fast} provides the user an umbrella option to
   simplify access to the many single purpose floating point options. The default
   setting is ``precise``.

 - The default module cache has moved from /tmp to a per-user cache directory.
   By default, this is ~/.cache but on some platforms or installations, this
   might be elsewhere. The -fmodules-cache-path=... flag continues to work.

 - -fpch-instantiate-templates tries to instantiate templates already while
   generating a precompiled header. Such templates do not need to be
   instantiated every time the precompiled header is used, which saves compile
   time. This may result in an error during the precompiled header generation
   if the source header file is not self-contained. This option is enabled
   by default for clang-cl.

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

 The following options are deprecated and ignored. They will be removed in
 future versions of Clang.

 - ...

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

 - -fno-common has been enabled as the default for all targets.  Therefore, C
   code that uses tentative definitions as definitions of a variable in multiple
   translation units will trigger multiple-definition linker errors. Generally,
   this occurs when the use of the ``extern`` keyword is neglected in the
   declaration of a variable in a header file. In some cases, no specific
   translation unit provides a definition of the variable. The previous
   behavior can be restored by specifying ``-fcommon``.
 - -Wasm-ignored-qualifier (ex. `asm const ("")`) has been removed and replaced
   with an error (this matches a recent change in GCC-9).
 - -Wasm-file-asm-volatile (ex. `asm volatile ("")` at global scope) has been
   removed and replaced with an error (this matches GCC's behavior).
 - Duplicate qualifiers on asm statements (ex. `asm volatile volatile ("")`) no
   longer produces a warning via -Wduplicate-decl-specifier, but now an error
   (this matches GCC's behavior).
 - The deprecated argument ``-f[no-]sanitize-recover`` has changed to mean
   ``-f[no-]sanitize-recover=all`` instead of
   ``-f[no-]sanitize-recover=undefined,integer`` and is no longer deprecated.
 - The argument to ``-f[no-]sanitize-trap=...`` is now optional and defaults to
   ``all``.
 - ``-fno-char8_t`` now disables the ``char8_t`` keyword, not just the use of
   ``char8_t`` as the character type of ``u8`` literals. This restores the
   Clang 8 behavior that regressed in Clang 9 and 10.
 - -print-targets has been added to print the registered targets.

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

 - ...

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

 - Attributes can now be specified by clang plugins. See the
   `Clang Plugins <ClangPlugins.html#defining-attributes>`_ documentation for
   details.

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

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

 - The default C language standard used when `-std=` is not specified has been
   upgraded from gnu11 to gnu17.

 - Clang now supports the GNU C extension `asm inline`; it won't do anything
   *yet*, but it will be parsed.

 - ...

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

 - Clang now implements a restriction on giving non-C-compatible anonymous
   structs a typedef name for linkage purposes, as described in C++ committee
   paper `P1766R1 <http://wg21.link/p1766r1>`. This paper was adopted by the
   C++ committee as a Defect Report resolution, so it is applied retroactively
   to all C++ standard versions. This affects code such as:

   .. code-block:: c++

     typedef struct {
       int f() { return 0; }
     } S;

   Previous versions of Clang rejected some constructs of this form
   (specifically, where the linkage of the type happened to be computed
   before the parser reached the typedef name); those cases are still rejected
   in Clang 11. In addition, cases that previous versions of Clang did not
   reject now produce an extension warning. This warning can be disabled with
   the warning flag ``-Wno-non-c-typedef-for-linkage``.

   Affected code should be updated to provide a tag name for the anonymous
   struct:

   .. code-block:: c++

     struct S {
       int f() { return 0; }
     };

   If the code is shared with a C compilation (for example, if the parts that
   are not C-compatible are guarded with ``#ifdef __cplusplus``), the typedef
   declaration should be retained, but a tag name should still be provided:

   .. code-block:: c++

     typedef struct S {
       int f() { return 0; }
     } S;

 C++1z Feature Support
 ^^^^^^^^^^^^^^^^^^^^^

 ...

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

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

 ...

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

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

 - ...

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

 - ...

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

 These are major API changes that have happened since the 10.0.0 release of
 Clang. If upgrading an external codebase that uses Clang as a library,
 this section should help get you past the largest hurdles of upgrading.

 - ``RecursiveASTVisitor`` no longer calls separate methods to visit specific
   operator kinds. Previously, ``RecursiveASTVisitor`` treated unary, binary,
   and compound assignment operators as if they were subclasses of the
   corresponding AST node. For example, the binary operator plus was treated as
   if it was a ``BinAdd`` subclass of the ``BinaryOperator`` class: during AST
   traversal of a ``BinaryOperator`` AST node that had a ``BO_Add`` opcode,
   ``RecursiveASTVisitor`` was calling the ``TraverseBinAdd`` method instead of
   ``TraverseBinaryOperator``. This feature was contributing a non-trivial
   amount of complexity to the implementation of ``RecursiveASTVisitor``, it was
   used only in a minor way in Clang, was not tested, and as a result it was
   buggy. Furthermore, this feature was creating a non-uniformity in the API.
   Since this feature was not documented, it was quite difficult to figure out
   how to use ``RecursiveASTVisitor`` to visit operators.

   To update your code to the new uniform API, move the code from separate
   visitation methods into methods that correspond to the actual AST node and
   perform case analysis based on the operator opcode as needed:

   * ``TraverseUnary*() => TraverseUnaryOperator()``
   * ``WalkUpFromUnary*() => WalkUpFromUnaryOperator()``
   * ``VisitUnary*() => VisiUnaryOperator()``
   * ``TraverseBin*() => TraverseBinaryOperator()``
   * ``WalkUpFromBin*() => WalkUpFromBinaryOperator()``
   * ``VisitBin*() => VisiBinaryOperator()``
   * ``TraverseBin*Assign() => TraverseCompoundAssignOperator()``
   * ``WalkUpFromBin*Assign() => WalkUpFromCompoundAssignOperator()``
   * ``VisitBin*Assign() => VisiCompoundAssignOperator()``

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

 These are major changes to the build system that have happened since the 10.0.0
 release of Clang. Users of the build system should adjust accordingly.

 - clang-tidy and clang-include-fixer are no longer compiled into libclang by
   default. You can set ``LIBCLANG_INCLUDE_CLANG_TOOLS_EXTRA=ON`` to undo that,
   but it's expected that that setting will go away eventually. If this is
   something you need, please reach out to the mailing list to discuss possible
   ways forward.

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

 - ...

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

 - Option ``IndentExternBlock`` has been added to optionally apply indenting inside ``extern "C"`` and ``extern "C++"`` blocks.

 - ``IndentExternBlock`` option accepts ``AfterExternBlock`` to use the old behavior, as well as Indent and NoIndent options, which map to true and false, respectively.

   .. code-block:: c++

     Indent:                       NoIndent:
      #ifdef __cplusplus          #ifdef __cplusplus
      extern "C" {                extern "C++" {
      #endif                      #endif

           void f(void);          void f(void);

      #ifdef __cplusplus          #ifdef __cplusplus
      }                           }
      #endif                      #endif

 - Option ``IndentCaseBlocks`` has been added to support treating the block
   following a switch case label as a scope block which gets indented itself.
   It helps avoid having the closing bracket align with the switch statement's
   closing bracket (when ``IndentCaseLabels`` is ``false``).

   .. code-block:: c++

     switch (fool) {                vs.     switch (fool) {
     case 1:                                case 1: {
       {                                      bar();
          bar();                            } break;
       }                                    default: {
       break;                                 plop();
     default:                               }
       {                                    }
         plop();
       }
     }

 - Option ``ObjCBreakBeforeNestedBlockParam`` has been added to optionally apply
   linebreaks for function arguments declarations before nested blocks.

 - Option ``InsertTrailingCommas`` can be set to ``TCS_Wrapped`` to insert
   trailing commas in container literals (arrays and objects) that wrap across
   multiple lines. It is currently only available for JavaScript and disabled by
   default (``TCS_None``).

 - Option ``BraceWrapping.BeforeLambdaBody`` has been added to manage lambda
   line break inside function parameter call in Allman style.

   .. code-block:: c++

       true:
       connect(
         []()
         {
           foo();
           bar();
         });

       false:
       connect([]() {
           foo();
           bar();
         });

 - Option ``AlignConsecutiveBitFields`` has been added to align bit field
   declarations across multiple adjacent lines

   .. code-block:: c++

       true:
         bool aaa  : 1;
         bool a    : 1;
         bool bb   : 1;

       false:
         bool aaa : 1;
         bool a : 1;
         bool bb : 1;

 - Option ``BraceWrapping.BeforeWhile`` has been added to allow wrapping
   before the ```while`` in a do..while loop. By default the value is (``false``)

   In previous releases ``IndentBraces`` implied ``BraceWrapping.BeforeWhile``.
   If using a Custom BraceWrapping style you may need to now set
   ``BraceWrapping.BeforeWhile`` to (``true``) to be explicit.

   .. code-block:: c++

       true:
       do {
         foo();
       }
       while(1);

       false:
       do {
         foo();
       } while(1);

 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 11.0.0 (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 11 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 11.0.0. 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 11.0.0?
	===========================

	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
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

	- -Wpointer-to-int-cast is a new warning group. This group warns about C-style
	casts of pointers to a integer type too small to hold all possible values.

	- -Wuninitialized-const-reference is a new warning controlled by
	-Wuninitialized. It warns on cases where uninitialized variables are passed
	as const reference arguments to a function.

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

	- For the ARM target, C-language intrinsics are now provided for the full Arm
	v8.1-M MVE instruction set. ``<arm_mve.h>`` supports the complete API defined
	in the Arm C Language Extensions.

	- For the ARM target, C-language intrinsics ``<arm_cde.h>`` for the CDE
	instruction set are now provided.

	- clang adds support for a set of extended integer types (``_ExtInt(N)``) that
	permit non-power of 2 integers, exposing the LLVM integer types. Since a major
	motivating use case for these types is to limit 'bit' usage, these types don't
	automatically promote to 'int' when operations are done between two
	``ExtInt(N)`` types, instead math occurs at the size of the largest
	``ExtInt(N)`` type.

	- Users of UBSan, PGO, and coverage on Windows will now need to add clang's
	library resource directory to their library search path. These features all
	use runtime libraries, and Clang provides these libraries in its resource
	directory. For example, if LLVM is installed in ``C:\Program Files\LLVM``,
	then the profile runtime library will appear at
	``C:\Program Files\LLVM\lib\clang\11.0.0\lib\windows\clang_rt.profile-x86_64.lib``.
	To ensure that the linker can find the appropriate library, users should pass
	``/LIBPATH:C:\Program Files\LLVM\lib\clang\11.0.0\lib\windows`` to the
	linker. If the user links the program with the ``clang`` or ``clang-cl``
	drivers, the driver will pass this flag for them.

	- Clang's profile files generated through ``-fprofile-instr-generate`` are using
	a fixed hashing algorithm that prevents some collision when loading
	out-of-date profile informations. Clang can still read old profile files.

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

	- -fstack-clash-protection will provide a protection against the stack clash
	attack for x86, s390x and ppc64 architectures through automatic probing of
	each page of allocated stack.

	- -ffp-exception-behavior={ignore,maytrap,strict} allows the user to specify
	the floating-point exception behavior. The default setting is ``ignore``.

	- -ffp-model={precise,strict,fast} provides the user an umbrella option to
	simplify access to the many single purpose floating point options. The default
	setting is ``precise``.

	- The default module cache has moved from /tmp to a per-user cache directory.
	By default, this is ~/.cache but on some platforms or installations, this
	might be elsewhere. The -fmodules-cache-path=... flag continues to work.

	- -fpch-instantiate-templates tries to instantiate templates already while
	generating a precompiled header. Such templates do not need to be
	instantiated every time the precompiled header is used, which saves compile
	time. This may result in an error during the precompiled header generation
	if the source header file is not self-contained. This option is enabled
	by default for clang-cl.

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

	The following options are deprecated and ignored. They will be removed in
	future versions of Clang.

	- ...

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

	- -fno-common has been enabled as the default for all targets. Therefore, C
	code that uses tentative definitions as definitions of a variable in multiple
	translation units will trigger multiple-definition linker errors. Generally,
	this occurs when the use of the ``extern`` keyword is neglected in the
	declaration of a variable in a header file. In some cases, no specific
	translation unit provides a definition of the variable. The previous
	behavior can be restored by specifying ``-fcommon``.
	- -Wasm-ignored-qualifier (ex. `asm const ("")`) has been removed and replaced
	with an error (this matches a recent change in GCC-9).
	- -Wasm-file-asm-volatile (ex. `asm volatile ("")` at global scope) has been
	removed and replaced with an error (this matches GCC's behavior).
	- Duplicate qualifiers on asm statements (ex. `asm volatile volatile ("")`) no
	longer produces a warning via -Wduplicate-decl-specifier, but now an error
	(this matches GCC's behavior).
	- The deprecated argument ``-f[no-]sanitize-recover`` has changed to mean
	``-f[no-]sanitize-recover=all`` instead of
	``-f[no-]sanitize-recover=undefined,integer`` and is no longer deprecated.
	- The argument to ``-f[no-]sanitize-trap=...`` is now optional and defaults to
	``all``.
	- ``-fno-char8_t`` now disables the ``char8_t`` keyword, not just the use of
	``char8_t`` as the character type of ``u8`` literals. This restores the
	Clang 8 behavior that regressed in Clang 9 and 10.
	- -print-targets has been added to print the registered targets.

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

	- ...

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

	- Attributes can now be specified by clang plugins. See the
	`Clang Plugins <ClangPlugins.html#defining-attributes>`_ documentation for
	details.

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

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

	- The default C language standard used when `-std=` is not specified has been
	upgraded from gnu11 to gnu17.

	- Clang now supports the GNU C extension `asm inline`; it won't do anything
	yet, but it will be parsed.

	- ...

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

	- Clang now implements a restriction on giving non-C-compatible anonymous
	structs a typedef name for linkage purposes, as described in C++ committee
	paper `P1766R1 <http://wg21.link/p1766r1>`. This paper was adopted by the
	C++ committee as a Defect Report resolution, so it is applied retroactively
	to all C++ standard versions. This affects code such as:

	.. code-block:: c++

	typedef struct {
	int f() { return 0; }
	} S;

	Previous versions of Clang rejected some constructs of this form
	(specifically, where the linkage of the type happened to be computed
	before the parser reached the typedef name); those cases are still rejected
	in Clang 11. In addition, cases that previous versions of Clang did not
	reject now produce an extension warning. This warning can be disabled with
	the warning flag ``-Wno-non-c-typedef-for-linkage``.

	Affected code should be updated to provide a tag name for the anonymous
	struct:

	.. code-block:: c++

	struct S {
	int f() { return 0; }
	};

	If the code is shared with a C compilation (for example, if the parts that
	are not C-compatible are guarded with ``#ifdef __cplusplus``), the typedef
	declaration should be retained, but a tag name should still be provided:

	.. code-block:: c++

	typedef struct S {
	int f() { return 0; }
	} S;

	C++1z Feature Support
	^^^^^^^^^^^^^^^^^^^^^

	...

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

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

	...

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

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

	- ...

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

	- ...

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

	These are major API changes that have happened since the 10.0.0 release of
	Clang. If upgrading an external codebase that uses Clang as a library,
	this section should help get you past the largest hurdles of upgrading.

	- ``RecursiveASTVisitor`` no longer calls separate methods to visit specific
	operator kinds. Previously, ``RecursiveASTVisitor`` treated unary, binary,
	and compound assignment operators as if they were subclasses of the
	corresponding AST node. For example, the binary operator plus was treated as
	if it was a ``BinAdd`` subclass of the ``BinaryOperator`` class: during AST
	traversal of a ``BinaryOperator`` AST node that had a ``BO_Add`` opcode,
	``RecursiveASTVisitor`` was calling the ``TraverseBinAdd`` method instead of
	``TraverseBinaryOperator``. This feature was contributing a non-trivial
	amount of complexity to the implementation of ``RecursiveASTVisitor``, it was
	used only in a minor way in Clang, was not tested, and as a result it was
	buggy. Furthermore, this feature was creating a non-uniformity in the API.
	Since this feature was not documented, it was quite difficult to figure out
	how to use ``RecursiveASTVisitor`` to visit operators.

	To update your code to the new uniform API, move the code from separate
	visitation methods into methods that correspond to the actual AST node and
	perform case analysis based on the operator opcode as needed:

	* ``TraverseUnary*() => TraverseUnaryOperator()``
	* ``WalkUpFromUnary*() => WalkUpFromUnaryOperator()``
	* ``VisitUnary*() => VisiUnaryOperator()``
	* ``TraverseBin*() => TraverseBinaryOperator()``
	* ``WalkUpFromBin*() => WalkUpFromBinaryOperator()``
	* ``VisitBin*() => VisiBinaryOperator()``
	* ``TraverseBin*Assign() => TraverseCompoundAssignOperator()``
	* ``WalkUpFromBin*Assign() => WalkUpFromCompoundAssignOperator()``
	* ``VisitBin*Assign() => VisiCompoundAssignOperator()``

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

	These are major changes to the build system that have happened since the 10.0.0
	release of Clang. Users of the build system should adjust accordingly.

	- clang-tidy and clang-include-fixer are no longer compiled into libclang by
	default. You can set ``LIBCLANG_INCLUDE_CLANG_TOOLS_EXTRA=ON`` to undo that,
	but it's expected that that setting will go away eventually. If this is
	something you need, please reach out to the mailing list to discuss possible
	ways forward.

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

	- ...

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

	- Option ``IndentExternBlock`` has been added to optionally apply indenting inside ``extern "C"`` and ``extern "C++"`` blocks.

	- ``IndentExternBlock`` option accepts ``AfterExternBlock`` to use the old behavior, as well as Indent and NoIndent options, which map to true and false, respectively.

	.. code-block:: c++

	Indent: NoIndent:
	#ifdef __cplusplus #ifdef __cplusplus
	extern "C" { extern "C++" {
	#endif #endif

	void f(void); void f(void);

	#ifdef __cplusplus #ifdef __cplusplus
	} }
	#endif #endif

	- Option ``IndentCaseBlocks`` has been added to support treating the block
	following a switch case label as a scope block which gets indented itself.
	It helps avoid having the closing bracket align with the switch statement's
	closing bracket (when ``IndentCaseLabels`` is ``false``).

	.. code-block:: c++

	switch (fool) { vs. switch (fool) {
	case 1: case 1: {
	{ bar();
	bar(); } break;
	} default: {
	break; plop();
	default: }
	{ }
	plop();
	}
	}

	- Option ``ObjCBreakBeforeNestedBlockParam`` has been added to optionally apply
	linebreaks for function arguments declarations before nested blocks.

	- Option ``InsertTrailingCommas`` can be set to ``TCS_Wrapped`` to insert
	trailing commas in container literals (arrays and objects) that wrap across
	multiple lines. It is currently only available for JavaScript and disabled by
	default (``TCS_None``).

	- Option ``BraceWrapping.BeforeLambdaBody`` has been added to manage lambda
	line break inside function parameter call in Allman style.

	.. code-block:: c++

	true:
	connect(
	[]()
	{
	foo();
	bar();
	});

	false:
	connect([]() {
	foo();
	bar();
	});

	- Option ``AlignConsecutiveBitFields`` has been added to align bit field
	declarations across multiple adjacent lines

	.. code-block:: c++

	true:
	bool aaa : 1;
	bool a : 1;
	bool bb : 1;

	false:
	bool aaa : 1;
	bool a : 1;
	bool bb : 1;

	- Option ``BraceWrapping.BeforeWhile`` has been added to allow wrapping
	before the ```while`` in a do..while loop. By default the value is (``false``)

	In previous releases ``IndentBraces`` implied ``BraceWrapping.BeforeWhile``.
	If using a Custom BraceWrapping style you may need to now set
	``BraceWrapping.BeforeWhile`` to (``true``) to be explicit.

	.. code-block:: c++

	true:
	do {
	foo();
	}
	while(1);

	false:
	do {
	foo();
	} while(1);

	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>`_.