Bump the trunk major version to 11

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

Extra Clang Tools 10.0.0 (In-Progress) Release Notes

Extra Clang Tools 11.0.0 (In-Progress) Release Notes

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

.. contents::

.. warning::

   These are in-progress notes for the upcoming Extra Clang Tools 10 release.

   These are in-progress notes for the upcoming Extra Clang Tools 11 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 10.0.0. Here we describe the status of the Extra Clang Tools in

Clang release 11.0.0. 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 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 Subversion checkout or the

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 Extra Clang Tools 10.0.0?

What's New in Extra Clang Tools 11.0.0?

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

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

Improvements to clang-doc

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

- :doc:`clang-doc <clang-doc>` now generates documentation in HTML format.

The improvements are...

Improvements to clang-query

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

New checks

^^^^^^^^^^

- New :doc:`bugprone-bad-signal-to-kill-thread

  <clang-tidy/checks/bugprone-bad-signal-to-kill-thread>` check.

  Finds ``pthread_kill`` function calls when a thread is terminated by 

  raising ``SIGTERM`` signal.

- New :doc:`bugprone-dynamic-static-initializers

  <clang-tidy/checks/bugprone-dynamic-static-initializers>` check.

  Finds instances where variables with static storage are initialized

  dynamically in header files.

- New :doc:`bugprone-infinite-loop

  <clang-tidy/checks/bugprone-infinite-loop>` check.

  Finds obvious infinite loops (loops where the condition variable is not

  changed at all).

- New :doc:`bugprone-not-null-terminated-result

  <clang-tidy/checks/bugprone-not-null-terminated-result>` check

  Finds function calls where it is possible to cause a not null-terminated

  result.

- New :doc:`bugprone-signed-char-misuse

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

  Finds ``signed char`` to integer conversions which might indicate a

  programming error.

- New :doc:`cert-mem57-cpp

  <clang-tidy/checks/cert-mem57-cpp>` check.

  Checks if an object of type with extended alignment is allocated by using

  the default ``operator new``.

- New :doc:`cert-oop58-cpp

  <clang-tidy/checks/cert-oop58-cpp>` check.

  Finds assignments to the copied object and its direct or indirect members

  in copy constructors and copy assignment operators.

- New :doc:`cppcoreguidelines-init-variables

  <clang-tidy/checks/cppcoreguidelines-init-variables>` check.

  Checks whether there are local variables that are declared without an initial

  value.

- New :doc:`darwin-dispatch-once-nonstatic

  <clang-tidy/checks/darwin-dispatch-once-nonstatic>` check.

  Finds declarations of ``dispatch_once_t`` variables without static or global

  storage.

- New :doc:`google-upgrade-googletest-case

  <clang-tidy/checks/google-upgrade-googletest-case>` check.

  Finds uses of deprecated Googletest APIs with names containing ``case`` and

  replaces them with equivalent APIs with ``suite``.

- New :doc:`linuxkernel-must-use-errs

  <clang-tidy/checks/linuxkernel-must-use-errs>` check.

  Checks Linux kernel code to see if it uses the results from the functions in

  ``linux/err.h``.

- New :doc:`llvm-prefer-register-over-unsigned

  <clang-tidy/checks/llvm-prefer-register-over-unsigned>` check.

  Finds historical use of ``unsigned`` to hold vregs and physregs and rewrites

  them to use ``Register``

- New :doc:`objc-missing-hash

  <clang-tidy/checks/objc-missing-hash>` check.

  Finds Objective-C implementations that implement ``-isEqual:`` without also

  appropriately implementing ``-hash``.

- New :doc:`performance-no-automatic-move

  <clang-tidy/checks/performance-no-automatic-move>` check.

  Finds local variables that cannot be automatically moved due to constness.

- New :doc:`performance-trivially-destructible

  <clang-tidy/checks/performance-trivially-destructible>` check.

  Finds types that could be made trivially-destructible by removing out-of-line

  defaulted destructor declarations.

- New :doc:`readability-make-member-function-const

  <clang-tidy/checks/readability-make-member-function-const>` check.

  Finds non-static member functions that can be made ``const``

  because the functions don't use ``this`` in a non-const way.

- New :doc:`readability-qualified-auto

  <clang-tidy/checks/readability-qualified-auto>` check.

  Adds pointer and ``const`` qualifications to ``auto``-typed variables 

  that are deduced to pointers and ``const`` pointers.

- New :doc:`readability-redundant-access-specifiers

  <clang-tidy/checks/readability-redundant-access-specifiers>` check.

  Finds classes, structs, and unions that contain redundant member

  access specifiers.

New aliases

^^^^^^^^^^^

- New alias :doc:`cert-pos44-c

  <clang-tidy/checks/cert-pos44-c>` to

  :doc:`bugprone-bad-signal-to-kill-thread

  <clang-tidy/checks/bugprone-bad-signal-to-kill-thread>` was added.

- New alias :doc:`llvm-qualified-auto

  <clang-tidy/checks/llvm-qualified-auto>` to

  :doc:`readability-qualified-auto

  <clang-tidy/checks/readability-qualified-auto>` was added.

Changes in existing checks

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

- Improved :doc:`bugprone-posix-return

  <clang-tidy/checks/bugprone-posix-return>` check.

  Now also checks if any calls to ``pthread_*`` functions expect negative

  return values.

- Improved :doc:`hicpp-signed-bitwise

  <clang-tidy/checks/hicpp-signed-bitwise>` check.

  The check now supports the `IgnorePositiveIntegerLiterals` option.

- Improved :doc:`modernize-avoid-bind

  <clang-tidy/checks/modernize-avoid-bind>` check.

  The check now supports supports diagnosing and fixing arbitrary callables

  instead of only simple free functions. The `PermissiveParameterList` option

  has also been added to address situations where the existing fix-it logic

  would sometimes generate code that no longer compiles.

- The :doc:`modernize-use-equals-default

  <clang-tidy/checks/modernize-use-equals-default>` fix no longer adds

  semicolons where they would be redundant.

- Improved :doc:`modernize-use-override

  <clang-tidy/checks/modernize-use-override>` check.

  The check now supports the `AllowOverrideAndFinal` option to eliminate

  conflicts with `gcc -Wsuggest-override` or `gcc -Werror=suggest-override`.

- The :doc:`modernize-use-using

  <clang-tidy/checks/modernize-use-using>` check now converts typedefs

  containing struct definitions and multiple comma-separated types.

- Improved :doc:`readability-magic-numbers

  <clang-tidy/checks/readability-magic-numbers>` check.

  The check now supports the `IgnoreBitFieldsWidths` option to suppress

  the warning for numbers used to specify bit field widths.

  The check was updated to eliminate some false positives (such as using

  class enumeration as non-type template parameters, or the synthetically

  computed length of a static user string literal.)

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

  <clang-tidy/checks/readability-redundant-member-init>` check.

  The check  now supports the `IgnoreBaseInCopyConstructors` option to avoid

  `"base class 'Foo' should be explicitly initialized in the copy constructor"`

  warnings or errors with `gcc -Wextra` or `gcc -Werror=extra`.

- The :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.

Renamed checks

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

- The 'objc-avoid-spinlock' check was renamed to :doc:`darwin-avoid-spinlock

  <clang-tidy/checks/darwin-avoid-spinlock>`

Improvements to include-fixer

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

Clang-tidy visual studio plugin

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

The clang-tidy-vs plugin has been removed from clang, as

it's no longer maintained. Users should migrate to

`Clang Power Tools <https://marketplace.visualstudio.com/items?itemName=caphyon.ClangPowerTools>`_

instead.

# built documents.

#

# The short version.

version = '10'

version = '11'

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

release = '10'

release = '11'

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

# for a list of supported languages.

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

Clang 10.0.0 (In-Progress) Release Notes

Clang 11.0.0 (In-Progress) Release Notes

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

.. contents::

.. warning::

   These are in-progress notes for the upcoming Clang 10 release.

   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>`_.

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

This document contains the release notes for the Clang C/C++/Objective-C

frontend, part of the LLVM Compiler Infrastructure, release 10.0.0. Here we

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

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 Subversion checkout or the

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 10.0.0?

What's New in Clang 11.0.0?

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

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

Improvements to Clang's diagnostics

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

- -Wtautological-overlap-compare will warn on negative numbers and non-int

  types.

- -Wtautological-compare for self comparisons and

  -Wtautological-overlap-compare will now look through member and array

  access to determine if two operand expressions are the same.

- -Wtautological-bitwise-compare is a new warning group.  This group has the

  current warning which diagnoses the tautological comparison of a bitwise

  operation and a constant. The group also has the new warning which diagnoses

  when a bitwise-or with a non-negative value is converted to a bool, since

  that bool will always be true.

- -Wbitwise-conditional-parentheses will warn on operator precedence issues

  when mixing bitwise-and (&) and bitwise-or (|) operator with the

  conditional operator (?:).

- -Wrange-loop-analysis got several improvements. It no longer warns about a

  copy being made when the result is bound to an rvalue reference. It no longer

  warns when an object of a small, trivially copyable type is copied. The

  warning now offers fixits. It is now part of -Wall.

- ...

Non-comprehensive list of changes in this release

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

* In both C and C++ (C17 ``6.5.6p8``, C++ ``[expr.add]``), pointer arithmetic is

  only permitted within arrays. In particular, the behavior of a program is not

  defined if it adds a non-zero offset (or in C, any offset) to a null pointer,

  or if it forms a null pointer by subtracting an integer from a non-null

  pointer, and the LLVM optimizer now uses those guarantees for transformations.

  This may lead to unintended behavior in code that performs these operations.

  The Undefined Behavior Sanitizer ``-fsanitize=pointer-overflow`` check has

  been extended to detect these cases, so that code relying on them can be

  detected and fixed.

* The Implicit Conversion Sanitizer (``-fsanitize=implicit-conversion``) has

  learned to sanitize pre/post increment/decrement of types with bit width

  smaller than ``int``.

- For X86 target, -march=skylake-avx512, -march=icelake-client,

  -march=icelake-server, -march=cascadelake, -march=cooperlake will default to

  not using 512-bit zmm registers in vectorized code unless 512-bit intrinsics

  are used in the source code. 512-bit operations are known to cause the CPUs

  to run at a lower frequency which can impact performance. This behavior can be

  changed by passing -mprefer-vector-width=512 on the command line.

* clang now defaults to ``.init_array`` on Linux. It used to use ``.ctors`` if

  the found gcc installation is older than 4.7.0. Add ``-fno-use-init-array`` to

  get the old behavior (``.ctors``).

New Compiler Flags

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

- The -fgnuc-version= flag now controls the value of ``__GNUC__`` and related

  macros. This flag does not enable or disable any GCC extensions implemented in

  Clang. Setting the version to zero causes Clang to leave ``__GNUC__`` and

  other GNU-namespaced macros, such as ``__GXX_WEAK__``, undefined.

- vzeroupper insertion on X86 targets can now be disabled with -mno-vzeroupper.

  You can also force vzeroupper insertion to be used on CPUs that normally

  wouldn't with -mvzeroupper.

Deprecated Compiler Flags

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

The following options are deprecated and ignored. They will be removed in

future versions of Clang.

- -mmpx used to enable the __MPX__ preprocessor define for the Intel MPX

  instructions. There were no MPX intrinsics.

- -mno-mpx used to disable -mmpx and is the default behavior.

- ...

Modified Compiler Flags

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

- RISC-V now sets the architecture (riscv32/riscv64) based on the value provided

  to the ``-march`` flag, overriding the target provided by ``-triple``.

New Pragmas in Clang

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

Windows Support

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

- Previous Clang versions contained a work-around to avoid an issue with the

  standard library headers in Visual Studio 2019 versions prior to 16.3. This

  work-around has now been removed, and users of Visual Studio 2019 are

  encouraged to upgrade to 16.3 or later, otherwise they may see link errors as

  below:

  .. code-block:: console

    error LNK2005: "bool const std::_Is_integral<int>" (??$_Is_integral@H@std@@3_NB) already defined

C Language Changes in Clang

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

C++ Language Changes in Clang

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

- The behaviour of the `gnu_inline` attribute now matches GCC, for cases

  where used without the `extern` keyword. As this is a change compared to

  how it behaved in previous Clang versions, a warning is emitted for this

  combination.

C++1z Feature Support

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

Objective-C Language Changes in Clang

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

- In both Objective-C and

  Objective-C++, ``-Wcompare-distinct-pointer-types`` will now warn when

  comparing ObjC ``Class`` with an ObjC instance type pointer.

  .. code-block:: objc

    Class clz = ...;

    MyType *instance = ...;

    bool eq = (clz == instance); // Previously undiagnosed, now warns.

- Objective-C++ now diagnoses conversions between ``Class`` and ObjC

  instance type pointers. Such conversions already emitted an

  on-by-default ``-Wincompatible-pointer-types`` warning in Objective-C

  mode, but had inadvertently been missed entirely in

  Objective-C++. This has been fixed, and they are now diagnosed as

  errors, consistent with the usual C++ treatment for conversions

  between unrelated pointer types.

  .. code-block:: objc

    Class clz = ...;

    MyType *instance = ...;

    clz = instance; // Previously undiagnosed, now an error.

    instance = clz; // Previously undiagnosed, now an error.

  One particular issue you may run into is attempting to use a class

  as a key in a dictionary literal. This will now result in an error,

  because ``Class`` is not convertable to ``id<NSCopying>``. (Note that

  this was already a warning in Objective-C mode.) While an arbitrary

  ``Class`` object is not guaranteed to implement ``NSCopying``, the

  default metaclass implementation does. Therefore, the recommended

  solution is to insert an explicit cast to ``id``, which disables the

  type-checking here.

 .. code-block:: objc

    Class cls = ...;

    // Error: cannot convert from Class to id<NSCoding>.

    NSDictionary* d = @{cls : @"Hello"};

    // Fix: add an explicit cast to 'id'.

    NSDictionary* d = @{(id)cls : @"Hello"};

OpenCL C Language Changes in Clang

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

ABI Changes in Clang

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

- gcc passes vectors of __int128 in memory on X86-64. Clang historically

  broke the vectors into multiple scalars using two 64-bit values for each

  element. Clang now matches the gcc behavior on Linux and NetBSD. You can

  switch back to old API behavior with flag: -fclang-abi-compat=9.0.

- RISC-V now chooses a default ``-march=`` and ``-mabi=`` to match (in almost

  all cases) the GCC defaults. On baremetal targets, where neither ``-march=``

  nor ``-mabi=`` are specified, Clang now differs from GCC by defaulting to

  ``-march=rv32imac -mabi=ilp32`` or ``-march=rv64imac -mabi=lp64`` depending on

  the architecture in the target triple. These do not always match the defaults

  in Clang 9. We strongly suggest that you explicitly pass `-march=` and

  `-mabi=` when compiling for RISC-V, due to how extensible this architecture

  is.

OpenMP Support in Clang

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

Internal API Changes

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

These are major API changes that have happened since the 9.0.0 release of

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.

- libTooling APIs that transfer ownership of `FrontendAction` objects now pass

  them by `unique_ptr`, making the ownership transfer obvious in the type

  system. `FrontendActionFactory::create()` now returns a

  `unique_ptr<FrontendAction>`. `runToolOnCode`, `runToolOnCodeWithArgs`,

  `ToolInvocation::ToolInvocation()` now take a `unique_ptr<FrontendAction>`.

Build System Changes

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

These are major changes to the build system that have happened since the 9.0.0

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.

- In 8.0.0 and below, the install-clang-headers target would install clang's

  resource directory headers. This installation is now performed by the

  install-clang-resource-headers target. Users of the old install-clang-headers

  target should switch to the new install-clang-resource-headers target. The

  install-clang-headers target now installs clang's API headers (corresponding

  to its libraries), which is consistent with the install-llvm-headers target.

- In 9.0.0 and later Clang added a new target, clang-cpp, which generates a

  shared library comprised of all the clang component libraries and exporting

  the clang C++ APIs. Additionally the build system gained the new

  "CLANG_LINK_CLANG_DYLIB" option, which defaults Off, and when set to On, will

  force clang (and clang-based tools) to link the clang-cpp library instead of

  statically linking clang's components. This option will reduce the size of

  binary distributions at the expense of compiler performance.

- ...

AST Matchers

clang-format

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

- The ``Standard`` style option specifies which version of C++ should be used

  when parsing and formatting C++ code. The set of allowed values has changed:

  - ``Latest`` will always enable new C++ language features.

  - ``c++03``, ``c++11``, ``c++14``, ``c++17``, ``c++20`` will pin to exactly

    that language version.

  - ``Auto`` is the default and detects style from the code (this is unchanged).

  The previous values of ``Cpp03`` and ``Cpp11`` are deprecated. Note that

  ``Cpp11`` is treated as ``Latest``, as this was always clang-format's

  behavior. (One motivation for this change is the new name describes the

  behavior better).

- Clang-format has a new option called ``--dry-run`` or ``-n`` to emit a

  warning for clang-format violations. This can be used together

  with --ferror-limit=N to limit the number of warnings per file and --Werror

  to make warnings into errors.

- Option *IncludeIsMainSourceRegex* has been added to allow for additional

  suffixes and file extensions to be considered as a source file

  for execution of logic that looks for "main *include* file" to put

  it on top.

  By default, clang-format considers *source* files as "main" only when

  they end with: ``.c``, ``.cc``, ``.cpp``, ``.c++``, ``.cxx``,

  ``.m`` or ``.mm`` extensions. This config option allows to

  extend this set of source files considered as "main".

  For example, if this option is configured to ``(Impl\.hpp)$``,

  then a file ``ClassImpl.hpp`` is considered "main" (in addition to

  ``Class.c``, ``Class.cc``, ``Class.cpp`` and so on) and "main

  include file" logic will be executed (with *IncludeIsMainRegex* setting

  also being respected in later phase). Without this option set,

  ``ClassImpl.hpp`` would not have the main include file put on top

  before any other include.

- Options ``DeriveLineEnding`` and  ``UseCRLF`` have been added to allow

  clang-format to control the newlines. ``DeriveLineEnding`` is by default

  ``true`` and reflects is the existing mechanism, which based is on majority

  rule. The new options allows this to be turned off and ``UseCRLF`` to control

  the decision as to which sort of line ending to use.

- Option ``SpaceBeforeSquareBrackets`` has been added to insert a space before

  array declarations.

  .. code-block:: c++

    int a [5];    vs    int a[5];

- Clang-format now supports JavaScript null operators.

  .. code-block:: c++

    const x = foo ?? default;

    const z = foo?.bar?.baz;

libclang

--------

Static Analyzer

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

- The Clang analyzer checker ``DeadStores`` gets a new option called

  ``WarnForDeadNestedAssignments`` to detect nested dead assignments

  (enabled by default).

- ...

.. _release-notes-ubsan:

Undefined Behavior Sanitizer (UBSan)

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

- * The ``pointer-overflow`` check was extended added to catch the cases where

    a non-zero offset is applied to a null pointer, or the result of

    applying the offset is a null pointer.

    .. code-block:: c++

      #include <cstdint> // for intptr_t

      static char *getelementpointer_inbounds(char *base, unsigned long offset) {

        // Potentially UB.

        return base + offset;

      }

      char *getelementpointer_unsafe(char *base, unsigned long offset) {

        // Always apply offset. UB if base is ``nullptr`` and ``offset`` is not

        // zero, or if ``base`` is non-``nullptr`` and ``offset`` is

        // ``-reinterpret_cast<intptr_t>(base)``.

        return getelementpointer_inbounds(base, offset);

      }

      char *getelementpointer_safe(char *base, unsigned long offset) {

        // Cast pointer to integer, perform usual arithmetic addition,

        // and cast to pointer. This is legal.

        char *computed =

            reinterpret_cast<char *>(reinterpret_cast<intptr_t>(base) + offset);

        // If either the pointer becomes non-``nullptr``, or becomes

        // ``nullptr``, we must use ``computed`` result.

        if (((base == nullptr) && (computed != nullptr)) ||

            ((base != nullptr) && (computed == nullptr)))

          return computed;

        // Else we can use ``getelementpointer_inbounds()``.

        return getelementpointer_inbounds(base, offset);

      }

Core Analysis Improvements

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

# built documents.

#

# The short version.

version = '6'

version = '11'

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

release = '6'

release = '11'

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

# for a list of supported languages.

# built documents.

#

# The short version.

version = '10'

version = '11'

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

release = '10'

release = '11'

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

# for a list of supported languages.