====================================================
Extra Clang Tools |release| |ReleaseNotesTitle|
====================================================

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

.. only:: PreRelease

  .. warning::
     These are in-progress notes for the upcoming Extra Clang Tools |version| 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 Extra Clang Tools, part of the
Clang release |release|. 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/>`_.

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 Extra Clang Tools |release|?
==========================================

Some of the major new features and improvements to Extra Clang Tools are listed
here. Generic improvements to Extra Clang Tools as a whole or to its underlying
infrastructure are described first, followed by tool-specific sections.

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

Improvements to clangd
----------------------

Language feature support
^^^^^^^^^^^^^^^^^^^^^^^^

- Performance improvements and bugfixes to C++20 Modules support
- Improved support for C++23 "deducing this"
- Improvements to objective-c++ support

New Language Server Protocol features
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

- Added support for `textDocument/rangesFormatting`
- Added support for `positionEncoding`

Compile flags
^^^^^^^^^^^^^

- Added `BuiltinHeaders` config key which controls whether clangd's built-in
  headers are used or ones extracted from the driver.

Hover
^^^^^

- Fixed a bug that would sometimes prevent documentation comments of standard library functions
  from being shown

Code completion
^^^^^^^^^^^^^^^

- Added `HeaderInsertion` config option to control whether code completion inserts a missing
  header needed for the symbol being completed. This is equivalent to the `--header-insertion`
  command-line option.
- Added a `CodePatterns` config option to control whether code completion should offer code
  patterns as completions in addition to symbols.

Cross-references
^^^^^^^^^^^^^^^^

- References to symbols are now collected in array designators
- Find-references now works for operators new and delete
- Improvements to code navigation in templated code

Call hierarchy
^^^^^^^^^^^^^^

- Call hierarchy now works with the remote index
- Fixed a bug where call hierarchy could sometimes return bogus results

Inlay hints
^^^^^^^^^^^

- Parameter hint forwarding now works for variadic forwarding functions declared in header files
- Improved presentation of block-end hints

Code actions
^^^^^^^^^^^^

- Improved the rename refactor's name collision checking logic

Clang-tidy integration
^^^^^^^^^^^^^^^^^^^^^^

- Disabled the cppcoreguidelines-macro-to-enum checker which is incompatible with clangd

Include-cleaner integration
^^^^^^^^^^^^^^^^^^^^^^^^^^^

- Clangd now respects the `AngledHeaders` and `QuotedHeaders` config options for headers
  inserted to resolve include-cleaner diagnostics

Miscellaneous
^^^^^^^^^^^^^

- Various crash fixes and other stability improvements

Improvements to clang-doc
-------------------------

Improvements to clang-query
---------------------------

Improvements to include-cleaner
-------------------------------
- Deprecated the ``-insert`` and ``-remove`` command line options, and added
  the ``-disable-remove`` and ``-disable-insert`` command line options as
  replacements. The previous command line options were confusing because they
  did not imply the default state of the option (which is inserts and removes
  being enabled). The new options are easier to understand the semantics of.

Improvements to clang-tidy
--------------------------

- Changed the :program:`check_clang_tidy.py` tool to use FileCheck's
  ``--match-full-lines`` instead of ``strict-whitespace`` for ``CHECK-FIXES``
  clauses. Added a ``--match-partial-fixes`` option to keep previous behavior on
  specific tests. This may break tests for users with custom out-of-tree checks
  who use :program:`check_clang_tidy.py` as-is.

- Improved :program:`clang-tidy-diff.py` script. Add the `-warnings-as-errors`
  argument to treat warnings as errors.

- Improved :program:`clang-tidy` to show `CheckOptions` only for checks enabled
  in `Checks` when running ``--dump-config``.

- Fixed bug in :program:`clang-tidy` by which `HeaderFilterRegex` did not take
  effect when passed via the `.clang-tidy` file.

- Fixed bug in :program:`run_clang_tidy.py` where the program would not
  correctly display the checks enabled by the top-level `.clang-tidy` file.

New checks
^^^^^^^^^^

- New :doc:`bugprone-capturing-this-in-member-variable
  <clang-tidy/checks/bugprone/capturing-this-in-member-variable>` check.

  Finds lambda captures and ``bind`` function calls that capture the ``this``
  pointer and store it as class members without handle the copy and move
  constructors and the assignments.

- New :doc:`bugprone-misleading-setter-of-reference
  <clang-tidy/checks/bugprone/misleading-setter-of-reference>` check.

  Finds setter-like member functions that take a pointer parameter and set a
  reference member of the same class with the pointed value.

- New :doc:`bugprone-unintended-char-ostream-output
  <clang-tidy/checks/bugprone/unintended-char-ostream-output>` check.

  Finds unintended character output from ``unsigned char`` and ``signed char``
  to an ``ostream``.

- New :doc:`cppcoreguidelines-use-enum-class
  <clang-tidy/checks/cppcoreguidelines/use-enum-class>` check.

  Finds unscoped (non-class) ``enum`` declarations and suggests using
  ``enum class`` instead.

- New :doc:`llvm-prefer-static-over-anonymous-namespace
  <clang-tidy/checks/llvm/prefer-static-over-anonymous-namespace>` check.

  Finds function and variable declarations inside anonymous namespace and
  suggests replacing them with ``static`` declarations.

- New :doc:`modernize-use-scoped-lock
  <clang-tidy/checks/modernize/use-scoped-lock>` check.

  Finds uses of ``std::lock_guard`` and suggests replacing them with C++17's
  alternative ``std::scoped_lock``.

- New :doc:`portability-avoid-pragma-once
  <clang-tidy/checks/portability/avoid-pragma-once>` check.

  Finds uses of ``#pragma once`` and suggests replacing them with standard
  include guards (``#ifndef``/``#define``/``#endif``) for improved portability.

- New :doc:`readability-ambiguous-smartptr-reset-call
  <clang-tidy/checks/readability/ambiguous-smartptr-reset-call>` check.

  Finds potentially erroneous calls to ``reset`` method on smart pointers when
  the pointee type also has a ``reset`` method.

- New :doc:`readability-use-concise-preprocessor-directives
  <clang-tidy/checks/readability/use-concise-preprocessor-directives>` check.

  Finds uses of ``#if`` that can be simplified to ``#ifdef`` or ``#ifndef`` and,
  since C23 and C++23, uses of ``#elif`` that can be simplified to ``#elifdef``
  or ``#elifndef``.

New check aliases
^^^^^^^^^^^^^^^^^

Changes in existing checks
^^^^^^^^^^^^^^^^^^^^^^^^^^

- Improved :doc:`bugprone-crtp-constructor-accessibility
  <clang-tidy/checks/bugprone/crtp-constructor-accessibility>` check by fixing
  false positives on deleted constructors that cannot be used to construct
  objects, even if they have public or protected access.

- Improved :doc:`bugprone-exception-escape
  <clang-tidy/checks/bugprone/exception-escape>` check to print stack trace
  of a potentially escaped exception.

- Added an option to :doc:`bugprone-multi-level-implicit-pointer-conversion
  <clang-tidy/checks/bugprone/multi-level-implicit-pointer-conversion>` to
  choose whether to enable the check in C code or not.

- Improved :doc:`bugprone-optional-value-conversion
  <clang-tidy/checks/bugprone/optional-value-conversion>` check to detect
  conversion in argument of ``std::make_optional``.

- Improved :doc:`bugprone-sizeof-expression
  <clang-tidy/checks/bugprone/sizeof-expression>` check by adding
  `WarnOnSizeOfInLoopTermination` option to detect misuses of ``sizeof``
  expression in loop conditions.

- Improved :doc:`bugprone-string-constructor
  <clang-tidy/checks/bugprone/string-constructor>` check to find suspicious
  calls of ``std::string`` constructor with char pointer, start position and
  length parameters.

- Improved :doc:`bugprone-unchecked-optional-access
  <clang-tidy/checks/bugprone/unchecked-optional-access>` fixing false
  positives from smart pointer accessors repeated in checking ``has_value``
  and accessing ``value``. The option `IgnoreSmartPointerDereference` should
  no longer be needed and will be removed. Also fixing false positive from
  const reference accessors to objects containing optional member.

- Improved :doc:`bugprone-unsafe-functions
  <clang-tidy/checks/bugprone/unsafe-functions>` check to allow specifying
  additional C++ member functions to match.

- Improved :doc:`cert-err33-c
  <clang-tidy/checks/cert/err33-c>` check by fixing false positives when
  a function name is just prefixed with a targeted function name.

- Improved :doc:`concurrency-mt-unsafe
  <clang-tidy/checks/concurrency/mt-unsafe>` check by fixing a false positive
  where ``strerror`` was flagged as MT-unsafe.

- Improved :doc:`cppcoreguidelines-avoid-goto
  <clang-tidy/checks/cppcoreguidelines/avoid-goto>` check by adding the option
  `IgnoreMacros` to ignore ``goto`` labels defined in macros.

- Improved :doc:`cppcoreguidelines-interfaces-global-init
  <clang-tidy/checks/cppcoreguidelines/interfaces-global-init>` check by
  fixing false positives on uses of ``constinit`` variables.

- Improved :doc:`cppcoreguidelines-missing-std-forward
  <clang-tidy/checks/cppcoreguidelines/missing-std-forward>` check by adding a
  flag to specify the function used for forwarding instead of ``std::forward``.

- Improved :doc:`cppcoreguidelines-pro-bounds-pointer-arithmetic
  <clang-tidy/checks/cppcoreguidelines/pro-bounds-pointer-arithmetic>` check by
  fixing false positives when calling indexing operators that do not perform
  pointer arithmetic in template, for example ``std::map::operator[]`` and
  when pointer arithmetic was used through type aliases.

- Improved :doc:`cppcoreguidelines-rvalue-reference-param-not-moved
  <clang-tidy/checks/cppcoreguidelines/rvalue-reference-param-not-moved>` check
  by adding a flag to specify the function used for moving instead of
  ``std::move``.

- Improved :doc:`cppcoreguidelines-special-member-functions
  <clang-tidy/checks/cppcoreguidelines/special-member-functions>` check by
  adding the option `IgnoreMacros` to ignore classes defined in macros.

- Improved :doc:`google-readability-namespace-comments
  <clang-tidy/checks/google/readability-namespace-comments>` check by adding
  the option `AllowOmittingNamespaceComments` to accept if a namespace comment
  is omitted entirely.

- Improved :doc:`hicpp-avoid-goto
  <clang-tidy/checks/hicpp/avoid-goto>` check by adding the option
  `IgnoreMacros` to ignore ``goto`` labels defined in macros.

- Improved :doc:`hicpp-special-member-functions
  <clang-tidy/checks/hicpp/special-member-functions>` check by adding the
  option `IgnoreMacros` to ignore classes defined in macros.

- Improved :doc:`llvm-namespace-comment
  <clang-tidy/checks/llvm/namespace-comment>` check by adding the option
  `AllowOmittingNamespaceComments` to accept if a namespace comment is omitted
  entirely.

- Improved :doc:`misc-const-correctness
  <clang-tidy/checks/misc/const-correctness>` check by adding the option
  `AllowedTypes`, that excludes specified types from const-correctness
  checking and fixing false positives when modifying variant by ``operator[]``
  with template in parameters and supporting to check pointee mutation by
  `AnalyzePointers` option and fixing false positives when using const array
  type.

- Improved :doc:`misc-include-cleaner
  <clang-tidy/checks/misc/include-cleaner>` check by adding the options
  `UnusedIncludes` and `MissingIncludes`, which specify whether the check should
  report unused or missing includes respectively.

- Improved :doc:`misc-redundant-expression
  <clang-tidy/checks/misc/redundant-expression>` check by providing additional
  examples and fixing some macro related false positives.

- Improved :doc:`misc-unconventional-assign-operator
  <clang-tidy/checks/misc/unconventional-assign-operator>` check by fixing
  false positives when copy assignment operator function in a template class
  returns the result of another assignment to ``*this`` (``return *this=...``).

- Improved :doc:`misc-unused-using-decls
  <clang-tidy/checks/misc/unused-using-decls>` check by fixing false positives
  on ``operator""`` with template parameters.

- Improved :doc:`misc-use-internal-linkage
  <clang-tidy/checks/misc/use-internal-linkage>` check by fix false positives
  for function or variable in header file which contains macro expansion and
  excluding variables with ``thread_local`` storage class specifier from being
  matched.

- Improved :doc:`modernize-pass-by-value
  <clang-tidy/checks/modernize/pass-by-value>` check by fixing false positives
  when class passed by const-reference had a private move constructor.

- Improved :doc:`modernize-type-traits
  <clang-tidy/checks/modernize/type-traits>` check by detecting more type traits.

- Improved :doc:`modernize-use-default-member-init
  <clang-tidy/checks/modernize/use-default-member-init>` check by matching
  arithmetic operations, ``constexpr`` and ``static`` values, and detecting
  explicit casting of built-in types within member list initialization.

- Improved :doc:`modernize-use-designated-initializers
  <clang-tidy/checks/modernize/use-designated-initializers>` check by avoiding
  diagnosing designated initializers for ``std::array`` initializations.

- Improved :doc:`modernize-use-ranges
  <clang-tidy/checks/modernize/use-ranges>` check by updating suppress
  warnings logic for ``nullptr`` in ``std::find``.

- Improved :doc:`modernize-use-starts-ends-with
  <clang-tidy/checks/modernize/use-starts-ends-with>` check by adding more
  matched scenarios of ``find`` and ``rfind`` methods and fixing false
  positives when those methods were called with 3 arguments.

- Improved :doc:`modernize-use-std-numbers
  <clang-tidy/checks/modernize/use-std-numbers>` check to support math
  functions of different precisions.

- Improved :doc:`modernize-use-trailing-return-type
  <clang-tidy/checks/modernize/use-trailing-return-type>` check by adding
  support to modernize lambda signatures to use trailing return type and adding
  two new options: `TransformFunctions` and `TransformLambdas` to control
  whether function declarations and lambdas should be transformed by the check.
  Fixed false positives when lambda was matched as a function in C++11 mode.

- Improved :doc:`performance-move-const-arg
  <clang-tidy/checks/performance/move-const-arg>` check by fixing false
  negatives on ternary operators calling ``std::move``.

- Improved :doc:`performance-unnecessary-value-param
  <clang-tidy/checks/performance/unnecessary-value-param>` check performance by
  tolerating fix-it breaking compilation when functions is used as pointers
  to avoid matching usage of functions within the current compilation unit.
  Added an option `IgnoreCoroutines` with the default value `true` to
  suppress this check for coroutines where passing by reference may be unsafe.

- Improved :doc:`readability-convert-member-functions-to-static
  <clang-tidy/checks/readability/convert-member-functions-to-static>` check by
  fixing false positives on member functions with an explicit object parameter.

- Improved :doc:`readability-function-size
  <clang-tidy/checks/readability/function-size>` check by adding new option
  `CountMemberInitAsStmt` that allows counting class member initializers in
  constructors as statements.

- Improved :doc:`readability-math-missing-parentheses
  <clang-tidy/checks/readability/math-missing-parentheses>` check by fixing
  false negatives where math expressions are the operand of assignment operators
  or comparison operators.

- Improved :doc:`readability-named-parameter
  <clang-tidy/checks/readability/named-parameter>` check by adding the option
  `InsertPlainNamesInForwardDecls` to insert parameter names without comments
  for forward declarations only.

- Improved :doc:`readability-qualified-auto
  <clang-tidy/checks/readability/qualified-auto>` check by adding the option
  `AllowedTypes`, that excludes specified types from adding qualifiers.

- Improved :doc:`readability-redundant-inline-specifier
  <clang-tidy/checks/readability/redundant-inline-specifier>` check by fixing
  false positives on out-of-line explicitly defaulted functions.

- Improved :doc:`readability-redundant-smartptr-get
  <clang-tidy/checks/readability/redundant-smartptr-get>` check by fixing
  some false positives involving smart pointers to arrays.

Removed checks
^^^^^^^^^^^^^^

Miscellaneous
^^^^^^^^^^^^^

Improvements to include-fixer
-----------------------------

The improvements are...

Improvements to clang-include-fixer
-----------------------------------

The improvements are...

Improvements to modularize
--------------------------

The improvements are...

Improvements to pp-trace
------------------------

Clang-tidy Visual Studio plugin
-------------------------------
