Bump the trunk major version to 12

====================================================

Extra Clang Tools 11.0.0 (In-Progress) Release Notes

Extra Clang Tools 12.0.0 (In-Progress) Release Notes

====================================================

.. contents::

.. warning::

   These are in-progress notes for the upcoming Extra Clang Tools 11 release.

   These are in-progress notes for the upcoming Extra Clang Tools 12 release.

   Release notes for previous releases can be found on

   `the Download Page <https://releases.llvm.org/download.html>`_.

============

This document contains the release notes for the Extra Clang Tools, part of the

Clang release 11.0.0. Here we describe the status of the Extra Clang Tools in

Clang release 12.0.0. Here we describe the status of the Extra Clang Tools in

some detail, including major improvements from the previous release and new

feature work. All LLVM releases may be downloaded from the `LLVM releases web

site <https://llvm.org/releases/>`_.

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 Extra Clang Tools 11.0.0?

What's New in Extra Clang Tools 12.0.0?

=======================================

Some of the major new features and improvements to Extra Clang Tools are listed

Improvements to clang-tidy

--------------------------

New module

^^^^^^^^^^

- New module `llvmlibc`.

  This module contains checks related to the LLVM-libc coding standards.

New checks

^^^^^^^^^^

- New :doc:`abseil-string-find-str-contains

  <clang-tidy/checks/abseil-string-find-str-contains>` check.

  Finds ``s.find(...) == string::npos`` comparisons (for various string-like types)

  and suggests replacing with ``absl::StrContains()``.

- New :doc:`cppcoreguidelines-avoid-non-const-global-variables

  <clang-tidy/checks/cppcoreguidelines-avoid-non-const-global-variables>` check.

  Finds non-const global variables as described in check I.2 of C++ Core

  Guidelines.

- New :doc:`bugprone-misplaced-pointer-arithmetic-in-alloc

  <clang-tidy/checks/bugprone-misplaced-pointer-arithmetic-in-alloc>` check.

  Finds cases where an integer expression is added to or subtracted from the

  result of a memory allocation function (``malloc()``, ``calloc()``,

  ``realloc()``, ``alloca()``) instead of its argument.

- New :doc:`bugprone-no-escape

  <clang-tidy/checks/bugprone-no-escape>` check.

  Finds pointers with the ``noescape`` attribute that are captured by an

  asynchronously-executed block.

- New :doc:`bugprone-spuriously-wake-up-functions

  <clang-tidy/checks/bugprone-spuriously-wake-up-functions>` check.

  Finds ``cnd_wait``, ``cnd_timedwait``, ``wait``, ``wait_for``, or

  ``wait_until`` function calls when the function is not invoked from a loop

  that checks whether a condition predicate holds or the function has a

  condition parameter.

- New :doc:`bugprone-reserved-identifier

  <clang-tidy/checks/bugprone-reserved-identifier>` check.

  Checks for usages of identifiers reserved for use by the implementation.

- New :doc:`bugprone-suspicious-include

  <clang-tidy/checks/bugprone-suspicious-include>` check.

  Finds cases where an include refers to what appears to be an implementation

  file, which often leads to hard-to-track-down ODR violations, and diagnoses

  them.

- New :doc:`cert-oop57-cpp

  <clang-tidy/checks/cert-oop57-cpp>` check.

  Flags use of the `C` standard library functions ``memset``, ``memcpy`` and

  ``memcmp`` and similar derivatives on non-trivial types.

- New :doc:`llvmlibc-callee-namespace

  <clang-tidy/checks/llvmlibc-callee-namespace>` check.

  Checks all calls resolve to functions within ``__llvm_libc`` namespace.

- New :doc:`llvmlibc-implementation-in-namespace

  <clang-tidy/checks/llvmlibc-implementation-in-namespace>` check.

  Checks all llvm-libc implementation is within the correct namespace.

- New :doc:`llvmlibc-restrict-system-libc-headers

  <clang-tidy/checks/llvmlibc-restrict-system-libc-headers>` check.

  Finds includes of system libc headers not provided by the compiler within

  llvm-libc implementations.

- New :doc:`modernize-replace-disallow-copy-and-assign-macro

  <clang-tidy/checks/modernize-replace-disallow-copy-and-assign-macro>` check.

  Finds macro expansions of ``DISALLOW_COPY_AND_ASSIGN`` and replaces them with

  a deleted copy constructor and a deleted assignment operator.

- New :doc:`objc-dealloc-in-category

  <clang-tidy/checks/objc-dealloc-in-category>` check.

  Finds implementations of -dealloc in Objective-C categories.

- New :doc:`misc-no-recursion

  <clang-tidy/checks/misc-no-recursion>` check.

  Finds recursive functions and diagnoses them.

- New :doc:`objc-nsinvocation-argument-lifetime

  <clang-tidy/checks/objc-nsinvocation-argument-lifetime>` check.

  Finds calls to ``NSInvocation`` methods under ARC that don't have proper

  argument object lifetimes.

- New :doc:`readability-use-anyofallof

  <clang-tidy/checks/readability-use-anyofallof>` check.

  Finds range-based for loops that can be replaced by a call to ``std::any_of``

  or ``std::all_of``.

New check aliases

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

- New alias :doc:`cert-con36-c

  <clang-tidy/checks/cert-con36-c>` to

  :doc:`bugprone-spuriously-wake-up-functions

  <clang-tidy/checks/bugprone-spuriously-wake-up-functions>` was added.

- New alias :doc:`cert-con54-cpp

  <clang-tidy/checks/cert-con54-cpp>` to

  :doc:`bugprone-spuriously-wake-up-functions

  <clang-tidy/checks/bugprone-spuriously-wake-up-functions>` was added.

- New alias :doc:`cert-dcl37-c

  <clang-tidy/checks/cert-dcl37-c>` to

  :doc:`bugprone-reserved-identifier

  <clang-tidy/checks/bugprone-reserved-identifier>` was added.

- New alias :doc:`cert-dcl51-cpp

  <clang-tidy/checks/cert-dcl51-cpp>` to

  :doc:`bugprone-reserved-identifier

  <clang-tidy/checks/bugprone-reserved-identifier>` was added.

- New alias :doc:`cert-str34-c

  <clang-tidy/checks/cert-str34-c>` to

  :doc:`bugprone-signed-char-misuse

  <clang-tidy/checks/bugprone-signed-char-misuse>` was added.

- New alias :doc:`llvm-else-after-return

  <clang-tidy/checks/llvm-else-after-return>` to

  :doc:`readability-else-after-return

  <clang-tidy/checks/readability-else-after-return>` was added.

Changes in existing checks

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

- Improved :doc:`performance-faster-string-find

  <clang-tidy/checks/performance-faster-string-find>` check.

  Now checks ``std::basic_string_view`` by default.

- Improved :doc:`readability-else-after-return

  <clang-tidy/checks/readability-else-after-return>` check now supports a

  `WarnOnConditionVariables` option to control whether to refactor condition

  variables where possible.

- Improved :doc:`readability-identifier-naming

  <clang-tidy/checks/readability-identifier-naming>` check.

  Now able to rename member references in class template definitions with

  explicit access.

- Improved :doc:`readability-qualified-auto

  <clang-tidy/checks/readability-qualified-auto>` check now supports a

  `AddConstToQualified` to enable adding ``const`` qualifiers to variables

  typed with ``auto *`` and ``auto &``.

- Improved :doc:`readability-redundant-string-init

  <clang-tidy/checks/readability-redundant-string-init>` check now supports a

  `StringNames` option enabling its application to custom string classes. The

  check now detects in class initializers and constructor initializers which

  are deemed to be redundant.

- Checks supporting the ``HeaderFileExtensions`` flag now support ``;`` as a

  delimiter in addition to ``,``, with the latter being deprecated as of this

  release. This simplifies how one specifies the options on the command line:

  ``--config="{CheckOptions: [{ key: HeaderFileExtensions, value: h;;hpp;hxx }]}"``

Renamed checks

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

- The 'fuchsia-restrict-system-headers' check was renamed to :doc:`portability-restrict-system-includes

  <clang-tidy/checks/portability-restrict-system-includes>`

Other improvements

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

- For 'run-clang-tidy.py' add option to use alpha checkers from clang-analyzer.

The improvements are...

Improvements to include-fixer

-----------------------------

# built documents.

#

# The short version.

version = '11'

version = '12'

# The full version, including alpha/beta/rc tags.

release = '11'

release = '12'

# The language for content autogenerated by Sphinx. Refer to documentation

# for a list of supported languages.

========================================

Clang 11.0.0 (In-Progress) Release Notes

Clang 12.0.0 (In-Progress) Release Notes

========================================

.. contents::

.. warning::

   These are in-progress notes for the upcoming Clang 11 release.

   These are in-progress notes for the upcoming Clang 12 release.

   Release notes for previous releases can be found on

   `the Download Page <https://releases.llvm.org/download.html>`_.

============

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

frontend, part of the LLVM Compiler Infrastructure, release 12.0.0. 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

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?

What's New in Clang 12.0.0?

===========================

Some of the major new features and improvements to Clang are listed

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

-------------------------

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

Internal API Changes

--------------------

These are major API changes that have happened since the 10.0.0 release of

These are major API changes that have happened since the 11.0.0 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

These are major changes to the build system that have happened since the 11.0.0

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

--------

# built documents.

#

# The short version.

version = '11'

version = '12'

# The full version, including alpha/beta/rc tags.

release = '11'

release = '12'

# The language for content autogenerated by Sphinx. Refer to documentation

# for a list of supported languages.

# built documents.

#

# The short version.

version = '11'

version = '12'

# The full version, including alpha/beta/rc tags.

release = '11'

release = '12'

# The language for content autogenerated by Sphinx. Refer to documentation

# for a list of supported languages.