ReleaseNotes.rst

Extra Clang Tools |release| |ReleaseNotesTitle|

• Introduction
• What's New in Extra Clang Tools |release|?
  • Major New Features
  • Improvements to clangd
    • Inlay hints
    • Compile flags
    • Hover
    • Code completion
    • Code actions
    • Signature help
    • Cross-references
    • Objective-C
    • Miscellaneous
  • Improvements to clang-doc
  • Improvements to clang-query
  • Improvements to clang-rename
  • Improvements to clang-tidy
    • New checks
    • New check aliases
    • Changes in existing checks
    • Removed checks
  • Improvements to include-cleaner
  • Improvements to clang-include-fixer
  • Improvements to modularize
  • Improvements to pp-trace
  • Clang-tidy Visual Studio plugin

Written by the LLVM Team

.. 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.

For more information about Clang or LLVM, including information about the latest release, please see the Clang Web Site or the LLVM Web Site.

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.

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

Inlay hints

• Type hints

  • Improved heuristics for showing sugared vs. desguared types
  • Some hints which provide no information (e.g. <dependent-type>) are now omitted

• Parameter hints

  • Parameter hints are now shown for calls through function pointers
  • Parameter hints are now shown for calls to a class's operator()
  • No longer show bogus parameter hints for some builtins like __builtin_dump_struct

Compile flags

• System include extractor (--query-driver) improvements

  • The directory containing builtin headers is now excluded from extracted system includes
  • Various flags which can affect the system includes (--target, --stdlib, -specs) are now forwarded to the driver
  • Fixed a bug where clangd would sometimes try to call a driver that didn't have obj-c support with -x objective-c++-header
  • The driver path is now dot-normalized before being compared to the --query-driver pattern
  • --query-driver is now supported by clangd-indexer

• Fixed a regression in clangd 17 where response files would not be expanded

Hover

• Hover now shows alignment info for fields and records

Code completion

• Refined heuristics for determining whether the use of a function can be a call or not

Code actions

• The extract variable tweak gained support for extracting lambda expressions to a variable.
• A new tweak was added for turning unscoped into scoped enums.

Signature help

• Improved support for calls through function pointer types

Cross-references

• Improved support for C++20 concepts
• Find-references now works for labels
• Improvements to template heuristics

Objective-C

Miscellaneous

• Various stability improvements, e.g. crash fixes
• Improved error recovery on invalid code
• Clangd now bails gracefully on assembly and IR source files

Improvements to clang-doc

Improvements to clang-query

The improvements are...

Improvements to clang-rename

The improvements are...

Improvements to clang-tidy

• Preprocessor-level module header parsing is now disabled by default due to the problems it caused in C++20 and above, leading to performance and code parsing issues regardless of whether modules were used or not. This change will impact only the following checks: :doc:`modernize-replace-disallow-copy-and-assign-macro <clang-tidy/checks/modernize/replace-disallow-copy-and-assign-macro>`, :doc:`bugprone-reserved-identifier <clang-tidy/checks/bugprone/reserved-identifier>`, and :doc:`readability-identifier-naming <clang-tidy/checks/readability/identifier-naming>`. Those checks will no longer see macros defined in modules. Users can still enable this functionality using the newly added command line option --enable-module-headers-parsing.
• Remove configuration option AnalyzeTemporaryDestructors, which was deprecated since :program:`clang-tidy` 16.
• Improved --dump-config to print check options in alphabetical order.

• Improved :program:`clang-tidy-diff.py` script.

  • Return exit code 1 if any :program:`clang-tidy` subprocess exits with a non-zero code or if exporting fixes fails.
  • Accept a directory as a value for -export-fixes to export individual yaml files for each compilation unit.
  • Introduce a -config-file option that forwards a configuration file to :program:`clang-tidy`. Corresponds to the --config-file option in :program:`clang-tidy`.

• Improved :program:`run-clang-tidy.py` script. It now accepts a directory as a value for -export-fixes to export individual yaml files for each compilation unit.

New checks

• New :doc:`bugprone-casting-through-void <clang-tidy/checks/bugprone/casting-through-void>` check.

  Detects unsafe or redundant two-step casting operations involving void*.

• New :doc:`bugprone-chained-comparison <clang-tidy/checks/bugprone/chained-comparison>` check.

  Check detects chained comparison operators that can lead to unintended behavior or logical errors.

• New :doc:`bugprone-compare-pointer-to-member-virtual-function <clang-tidy/checks/bugprone/compare-pointer-to-member-virtual-function>` check.

  Detects equality comparison between pointer to member virtual function and anything other than null-pointer-constant.

• New :doc:`bugprone-inc-dec-in-conditions <clang-tidy/checks/bugprone/inc-dec-in-conditions>` check.

  Detects when a variable is both incremented/decremented and referenced inside a complex condition and suggests moving them outside to avoid ambiguity in the variable's value.

• New :doc:`bugprone-incorrect-enable-if <clang-tidy/checks/bugprone/incorrect-enable-if>` check.

  Detects incorrect usages of std::enable_if that don't name the nested type type.

• New :doc:`bugprone-multi-level-implicit-pointer-conversion <clang-tidy/checks/bugprone/multi-level-implicit-pointer-conversion>` check.

  Detects implicit conversions between pointers of different levels of indirection.

• New :doc:`bugprone-optional-value-conversion <clang-tidy/checks/bugprone/optional-value-conversion>` check.

  Detects potentially unintentional and redundant conversions where a value is extracted from an optional-like type and then used to create a new instance of the same optional-like type.

• New :doc:`bugprone-unused-local-non-trivial-variable <clang-tidy/checks/bugprone/unused-local-non-trivial-variable>` check.

  Warns when a local non trivial variable is unused within a function.

• New :doc:`cppcoreguidelines-no-suspend-with-lock <clang-tidy/checks/cppcoreguidelines/no-suspend-with-lock>` check.

  Flags coroutines that suspend while a lock guard is in scope at the suspension point.

• New :doc:`hicpp-ignored-remove-result <clang-tidy/checks/hicpp/ignored-remove-result>` check.

  Ensure that the result of std::remove, std::remove_if and std::unique are not ignored according to rule 17.5.1.

• New :doc:`misc-coroutine-hostile-raii <clang-tidy/checks/misc/coroutine-hostile-raii>` check.

  Detects when objects of certain hostile RAII types persists across suspension points in a coroutine. Such hostile types include scoped-lockable types and types belonging to a configurable denylist.

• New :doc:`misc-use-free-function-variants <clang-tidy/checks/misc/use-free-function-variants>` check.

  FIXME: add release notes.

• New :doc:`modernize-use-constraints <clang-tidy/checks/modernize/use-constraints>` check.

  Replace enable_if with C++20 requires clauses.

• New :doc:`modernize-use-starts-ends-with <clang-tidy/checks/modernize/use-starts-ends-with>` check.

  Checks whether a find or rfind result is compared with 0 and suggests replacing with starts_with when the method exists in the class. Notably, this will work with std::string and std::string_view.

• New :doc:`modernize-use-std-numbers <clang-tidy/checks/modernize/use-std-numbers>` check.

  Finds constants and function calls to math functions that can be replaced with C++20's mathematical constants from the numbers header and offers fix-it hints.

• New :doc:`performance-enum-size <clang-tidy/checks/performance/enum-size>` check.

  Recommends the smallest possible underlying type for an enum or enum class based on the range of its enumerators.

• New :doc:`readability-avoid-nested-conditional-operator <clang-tidy/checks/readability/avoid-nested-conditional-operator>` check.

  Identifies instances of nested conditional operators in the code.

• New :doc:`readability-avoid-return-with-void-value <clang-tidy/checks/readability/avoid-return-with-void-value>` check.

  Finds return statements with void values used within functions with void result types.

• New :doc:`readability-redundant-casting <clang-tidy/checks/readability/redundant-casting>` check.

  Detects explicit type casting operations that involve the same source and destination types, and subsequently recommend their removal.

• New :doc:`readability-redundant-inline-specifier <clang-tidy/checks/readability/redundant-inline-specifier>` check.

  Detects redundant inline specifiers on function and variable declarations.

• New :doc:`readability-reference-to-constructed-temporary <clang-tidy/checks/readability/reference-to-constructed-temporary>` check.

  Detects C++ code where a reference variable is used to extend the lifetime of a temporary object that has just been constructed.

New check aliases

• New alias :doc:`cppcoreguidelines-macro-to-enum <clang-tidy/checks/cppcoreguidelines/macro-to-enum>` to :doc:`modernize-macro-to-enum <clang-tidy/checks/modernize/macro-to-enum>` was added.

Changes in existing checks

• Improved :doc:`abseil-string-find-startswith <clang-tidy/checks/abseil/string-find-startswith>` check to also consider std::basic_string_view in addition to std::basic_string by default.
• Improved :doc:`bugprone-assert-side-effect <clang-tidy/checks/bugprone/assert-side-effect>` check to report usage of non-const << and >> operators in assertions and fixed some false-positives with const operators.
• Improved :doc:`bugprone-dangling-handle <clang-tidy/checks/bugprone/dangling-handle>` check to support functional casting during type conversions at variable initialization, now with improved compatibility for C++17 and later versions.
• Improved :doc:`bugprone-exception-escape <clang-tidy/checks/bugprone/exception-escape>` check by extending the default check function names to include iter_swap and iter_move.
• Improved :doc:`bugprone-implicit-widening-of-multiplication-result <clang-tidy/checks/bugprone/implicit-widening-of-multiplication-result>` check to correctly emit fixes.
• Improved :doc:`bugprone-lambda-function-name <clang-tidy/checks/bugprone/lambda-function-name>` check by adding option IgnoreMacros to ignore warnings in macros.
• Improved :doc:`bugprone-non-zero-enum-to-bool-conversion <clang-tidy/checks/bugprone/non-zero-enum-to-bool-conversion>` check by eliminating false positives resulting from direct usage of bitwise operators.
• Improved :doc:`bugprone-reserved-identifier <clang-tidy/checks/bugprone/reserved-identifier>` check, so that it does not warn on macros starting with underscore and lowercase letter.
• Improved :doc:`bugprone-sizeof-expression <clang-tidy/checks/bugprone/sizeof-expression>` check diagnostics to precisely highlight specific locations, providing more accurate guidance.
• Improved :doc:`bugprone-unchecked-optional-access <clang-tidy/checks/bugprone/unchecked-optional-access>` check, so that it does not crash during handling of optional values.
• Improved :doc:`bugprone-undefined-memory-manipulation <clang-tidy/checks/bugprone/undefined-memory-manipulation>` check to support fixed-size arrays of non-trivial types.
• Improved :doc:`bugprone-unused-return-value <clang-tidy/checks/bugprone/unused-return-value>` check diagnostic message, added support for detection of unused results when cast to non-void type. Casting to void no longer suppresses issues by default, control this behavior with the new AllowCastToVoid option.
• Improved :doc:`cppcoreguidelines-avoid-non-const-global-variables <clang-tidy/checks/cppcoreguidelines/avoid-non-const-global-variables>` check to ignore static variables declared within the scope of class/struct.
• Improved :doc:`cppcoreguidelines-avoid-reference-coroutine-parameters <clang-tidy/checks/cppcoreguidelines/avoid-reference-coroutine-parameters>` check to ignore false positives related to matching parameters of non coroutine functions and increase issue detection for cases involving type aliases with references.
• Improved :doc:`cppcoreguidelines-missing-std-forward <clang-tidy/checks/cppcoreguidelines/missing-std-forward>` check to address false positives in the capture list and body of lambdas.
• Improved :doc:`cppcoreguidelines-narrowing-conversions <clang-tidy/checks/cppcoreguidelines/narrowing-conversions>` check by extending the IgnoreConversionFromTypes option to include types without a declaration, such as built-in types.
• Improved :doc:`cppcoreguidelines-prefer-member-initializer <clang-tidy/checks/cppcoreguidelines/prefer-member-initializer>` check to ignore delegate constructors and ignore re-assignment for reference or when initialization depend on field that is initialized before. Additionally, it now provides valid fixes for member variables initialized with macros.
• Improved :doc:`cppcoreguidelines-pro-bounds-array-to-pointer-decay <clang-tidy/checks/cppcoreguidelines/pro-bounds-array-to-pointer-decay>` check to ignore predefined expression (e.g., __func__, ...).
• Improved :doc:`cppcoreguidelines-pro-bounds-constant-array-index <clang-tidy/checks/cppcoreguidelines/pro-bounds-constant-array-index>` check to perform checks on derived classes of std::array.
• Improved :doc:`cppcoreguidelines-pro-type-const-cast <clang-tidy/checks/cppcoreguidelines/pro-type-const-cast>` check to ignore casts to const or volatile type (controlled by StrictMode option) and casts in implicitly invoked code.
• Improved :doc:`cppcoreguidelines-pro-type-member-init <clang-tidy/checks/cppcoreguidelines/pro-type-member-init>` check to ignore dependent delegate constructors.
• Improved :doc:`cppcoreguidelines-pro-type-static-cast-downcast <clang-tidy/checks/cppcoreguidelines/pro-type-static-cast-downcast>` check to disregard casts on non-polymorphic types when the StrictMode option is set to false.
• Improved :doc:`cppcoreguidelines-pro-type-vararg <clang-tidy/checks/cppcoreguidelines/pro-type-vararg>` check to ignore false-positives in unevaluated context (e.g., decltype, sizeof, ...).
• Improved :doc:`cppcoreguidelines-rvalue-reference-param-not-moved <clang-tidy/checks/cppcoreguidelines/rvalue-reference-param-not-moved>` check to ignore unused parameters when they are marked as unused and parameters of deleted functions and constructors.
• Improved :doc:`google-readability-casting <clang-tidy/checks/google/readability-casting>` check to ignore constructor calls disguised as functional casts.
• Improved :doc:`google-runtime-int <clang-tidy/checks/google/runtime-int>` check to ignore false positives on user defined-literals.
• Improved :doc:`llvm-namespace-comment <clang-tidy/checks/llvm/namespace-comment>` check to provide fixes for inline namespaces in the same format as :program:`clang-format`.
• Improved :doc:`llvmlibc-callee-namespace <clang-tidy/checks/llvmlibc/callee-namespace>` to support customizable namespace. This matches the change made to implementation in namespace.
• Improved :doc:`llvmlibc-implementation-in-namespace <clang-tidy/checks/llvmlibc/implementation-in-namespace>` to support customizable namespace. This further allows for testing the libc when the system-libc is also LLVM's libc.
• Improved :doc:`llvmlibc-inline-function-decl <clang-tidy/checks/llvmlibc/inline-function-decl>` to properly ignore implicit functions, such as struct constructors, and explicitly deleted functions.
• Improved :doc:`misc-const-correctness <clang-tidy/checks/misc/const-correctness>` check to avoid false positive when using pointer to member function. Additionally, the check no longer emits a diagnostic when a variable that is not type-dependent is an operand of a type-dependent binary operator. Improved performance of the check through optimizations. The check no longer emits a diagnostic for non-parameter-pack variables in C++17 fold expressions.
• Improved :doc:`misc-include-cleaner <clang-tidy/checks/misc/include-cleaner>` check by adding option DeduplicateFindings to output one finding per symbol occurrence, avoid inserting the same header multiple times, fix a bug where IgnoreHeaders option won't work with verbatim/std headers.
• Improved :doc:`misc-redundant-expression <clang-tidy/checks/misc/redundant-expression>` check to ignore false-positives in unevaluated context (e.g., decltype).
• Improved :doc:`misc-static-assert <clang-tidy/checks/misc/static-assert>` check to ignore false-positives when referring to non-constexpr variables in non-unevaluated context.
• Improved :doc:`misc-unused-using-decls <clang-tidy/checks/misc/unused-using-decls>` check to avoid false positive when using in elaborated type and only check C++ files.
• Improved :doc:`modernize-avoid-bind <clang-tidy/checks/modernize/avoid-bind>` check to not emit a return for fixes when the function returns void and to provide valid fixes for cases involving bound C++ operators.
• Improved :doc:`modernize-loop-convert <clang-tidy/checks/modernize/loop-convert>` to support for-loops with iterators initialized by free functions like begin, end, or size and avoid crash for array of dependent array and non-dereferenceable builtin types used as iterators.
• Improved :doc:`modernize-make-shared <clang-tidy/checks/modernize/make-shared>` check to support std::shared_ptr implementations that inherit the reset method from a base class.
• Improved :doc:`modernize-return-braced-init-list <clang-tidy/checks/modernize/return-braced-init-list>` check to ignore false-positives when constructing the container with count copies of elements with value value.
• Improved :doc:`modernize-use-auto <clang-tidy/checks/modernize/use-auto>` to avoid create incorrect fix hints for pointer to array type and pointer to function type.
• Improved :doc:`modernize-use-emplace <clang-tidy/checks/modernize/use-emplace>` to not replace aggregates that emplace cannot construct with aggregate initialization.
• Improved :doc:`modernize-use-equals-delete <clang-tidy/checks/modernize/use-equals-delete>` check to ignore false-positives when special member function is actually used or implicit.
• Improved :doc:`modernize-use-nullptr <clang-tidy/checks/modernize/use-nullptr>` check by adding option IgnoredTypes that can be used to exclude some pointer types.
• Improved :doc:`modernize-use-std-print <clang-tidy/checks/modernize/use-std-print>` check to accurately generate fixes for reordering arguments.
• Improved :doc:`modernize-use-using <clang-tidy/checks/modernize/use-using>` check to fix function pointer and forward declared typedef correctly. Added option IgnoreExternC to ignore typedef declaration in extern "C" scope.
• Improved :doc:`performance-faster-string-find <clang-tidy/checks/performance/faster-string-find>` check to properly escape single quotes.
• Improved :doc:`performance-for-range-copy <clang-tidy/checks/performance/for-range-copy>` check to handle cases where the loop variable is a structured binding.
• Improved :doc:`performance-noexcept-move-constructor <clang-tidy/checks/performance/noexcept-move-constructor>` to better handle conditional noexcept expressions, eliminating false-positives.
• Improved :doc:`performance-noexcept-swap <clang-tidy/checks/performance/noexcept-swap>` check to enforce a stricter match with the swap function signature and better handling of condition noexcept expressions, eliminating false-positives. iter_swap function name is checked by default.
• Improved :doc:`readability-braces-around-statements <clang-tidy/checks/readability/braces-around-statements>` check to ignore false-positive for if constexpr in lambda expression.
• Improved :doc:`readability-avoid-const-params-in-decls <clang-tidy/checks/readability/avoid-const-params-in-decls>` diagnostics to highlight the const location
• Improved :doc:`readability-container-contains <clang-tidy/checks/readability/container-contains>` to correctly handle integer literals with suffixes in fix-its.
• Improved :doc:`readability-container-size-empty <clang-tidy/checks/readability/container-size-empty>` check to detect comparison between string and empty string literals and support length() method as an alternative to size(). Resolved false positives tied to negative values from size-like methods, and one triggered by size checks below zero.
• Improved :doc:`readability-function-size <clang-tidy/checks/readability/function-size>` check configuration to use none rather than -1 to disable some parameters.
• Improved :doc:`readability-identifier-naming <clang-tidy/checks/readability/identifier-naming>` check to issue accurate warnings when a type's forward declaration precedes its definition. Additionally, it now provides appropriate warnings for struct and union in C, while also incorporating support for the Leading_upper_snake_case naming convention. The handling of typedef has been enhanced, particularly within complex types like function pointers and cases where style checks were omitted when functions started with macros. Added support for C++20 concept declarations. Camel_Snake_Case and camel_Snake_Case now detect more invalid identifier names. Fields in anonymous records (i.e. anonymous structs and unions) now can be checked with the naming rules associated with their enclosing scopes rather than the naming rules of public struct/union members.
• Improved :doc:`readability-implicit-bool-conversion <clang-tidy/checks/readability/implicit-bool-conversion>` check to take do-while loops into account for the AllowIntegerConditions and AllowPointerConditions options. It also now provides more consistent suggestions when parentheses are added to the return value or expressions. It also ignores false-positives for comparison containing bool bitfield.
• Improved :doc:`readability-misleading-indentation <clang-tidy/checks/readability/misleading-indentation>` check to ignore false-positives for line started with empty macro.
• Improved :doc:`readability-non-const-parameter <clang-tidy/checks/readability/non-const-parameter>` check to ignore false-positives in initializer list of record.
• Improved :doc:`readability-redundant-member-init <clang-tidy/checks/readability/redundant-member-init>` check to now also detect redundant in-class initializers.
• Improved :doc:`readability-simplify-boolean-expr <clang-tidy/checks/readability/simplify-boolean-expr>` check by adding the new option IgnoreMacros that allows to ignore boolean expressions originating from expanded macros.
• Improved :doc:`readability-simplify-subscript-expr <clang-tidy/checks/readability/simplify-subscript-expr>` check by extending the default value of the Types option to include std::span.
• Improved :doc:`readability-static-accessed-through-instance <clang-tidy/checks/readability/static-accessed-through-instance>` check to identify calls to static member functions with out-of-class inline definitions.

Removed checks

Improvements to include-cleaner

• Support for --only-headers flag to limit analysis to headers matching a regex
• Recognizes references through ``concept``s
• Builtin headers are not analyzed
• Handling of references through friend declarations
• Fixes around handling of IWYU pragmas on stdlib headers
• Improved handling around references to/from template specializations

Improvements to clang-include-fixer

The improvements are...

Improvements to modularize

The improvements are...

Improvements to pp-trace

Clang-tidy Visual Studio plugin