clang/docs/ReleaseNotes.rst - 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.

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


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


 - -fstack-clash-protection will provide a protection against the stack clash
   attack for x86 architecture 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``.

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

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

 - ...

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


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

 - ...

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

 - ...

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

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

 - ...

 C11 Feature Support
 ^^^^^^^^^^^^^^^^^^^

 ...

 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.


 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.

 - ...

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

 - ...

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


 - 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``).

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

   .. code-block:: c++

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

 - 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();
         });

 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 Subversion 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.

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


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


	- -fstack-clash-protection will provide a protection against the stack clash
	attack for x86 architecture 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``.

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

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

	- ...

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


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

	- ...

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

	- ...

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

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

	- ...

	C11 Feature Support
	^^^^^^^^^^^^^^^^^^^

	...

	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.


	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.

	- ...

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

	- ...

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


	- 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``).

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

	.. code-block:: c++

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

	- 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();
	});

	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 Subversion 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>`_.