ReleaseNotes.rst

Extra Clang Tools

Written by the LLVM Team

PreRelease

Warning

These are in-progress notes for the upcoming Extra Clang Tools release. Release notes for previous releases can be found on the Download Page.

Introduction

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

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

Diagnostics

Semantic Highlighting

Compile flags

Hover

Code completion

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

Cross-references

Objective-C

Miscellaneous

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: modernize-replace-disallow-copy-and-assign-macro <clang-tidy/checks/modernize/replace-disallow-copy-and-assign-macro>, bugprone-reserved-identifier <clang-tidy/checks/bugprone/reserved-identifier>, and 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 clang-tidy 16.
• Improved --dump-config to print check options in alphabetical order.

• Improved clang-tidy-diff.py script.

  • Return exit code 1 if any 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 clang-tidy. Corresponds to the --config-file option in clang-tidy.

• Improved 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 bugprone-casting-through-void <clang-tidy/checks/bugprone/casting-through-void> check.

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

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

  Replace enable_if with C++20 requires clauses.

• New 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 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 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 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 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 check aliases

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

Changes in existing checks

• Improved 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 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 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 bugprone-lambda-function-name <clang-tidy/checks/bugprone/lambda-function-name> check by adding option IgnoreMacros to ignore warnings in macros.
• Improved 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 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 bugprone-sizeof-expression <clang-tidy/checks/bugprone/sizeof-expression> check diagnostics to precisely highlight specific locations, providing more accurate guidance.
• Improved bugprone-unchecked-optional-access <clang-tidy/checks/bugprone/unchecked-optional-access> check, so that it does not crash during handling of optional values.
• Improved bugprone-undefined-memory-manipulation <clang-tidy/checks/bugprone/undefined-memory-manipulation> check to support fixed-size arrays of non-trivial types.
• Improved 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 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 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 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 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.
• Improved 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 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 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 cppcoreguidelines-pro-type-member-init <clang-tidy/checks/cppcoreguidelines/pro-type-member-init> check to ignore dependent delegate constructors.
• Improved 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 cppcoreguidelines-pro-type-vararg <clang-tidy/checks/cppcoreguidelines/pro-type-vararg> check to ignore false-positives in unevaluated context (e.g., decltype, sizeof, ...).
• Improved 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 llvm-namespace-comment <clang-tidy/checks/llvm/namespace-comment> check to provide fixes for inline namespaces in the same format as clang-format.
• Improved llvmlibc-callee-namespace <clang-tidy/checks/llvmlibc/callee-namespace> to support customizable namespace. This matches the change made to implementation in namespace.
• Improved 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 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 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 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 misc-redundant-expression <clang-tidy/checks/misc/redundant-expression> check to ignore false-positives in unevaluated context (e.g., decltype).
• Improved misc-unused-using-decls <clang-tidy/checks/misc/unused-using-decls> check to avoid false positive when using in elaborated type.
• Improved 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 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.
• Improved 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 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 modernize-use-emplace <clang-tidy/checks/modernize/use-emplace> to not replace aggregates that emplace cannot construct with aggregate initialization.
• Improved 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 modernize-use-nullptr <clang-tidy/checks/modernize/use-nullptr> check by adding option IgnoredTypes that can be used to exclude some pointer types.
• Improved modernize-use-std-print <clang-tidy/checks/modernize/use-std-print> check to accurately generate fixes for reordering arguments.
• Improved 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 performance-faster-string-find <clang-tidy/checks/performance/faster-string-find> check to properly escape single quotes.
• Improved performance-noexcept-move-constructor <clang-tidy/checks/performance/noexcept-move-constructor> to better handle conditional noexcept expressions, eliminating false-positives.
• Improved 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.
• Improved readability-braces-around-statements <clang-tidy/checks/readability/braces-around-statements> check to ignore false-positive for if constexpr in lambda expression.
• Improved readability-avoid-const-params-in-decls <clang-tidy/checks/readability/avoid-const-params-in-decls> diagnositics to highlight the const location
• Improved readability-container-contains <clang-tidy/checks/readability/container-contains> to correctly handle interger literals with suffixes in fix-its.
• Improved 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().
• Improved readability-function-size <clang-tidy/checks/readability/function-size> check configuration to use none rather than -1 to disable some parameters.
• Improved 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 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.
• Improved readability-misleading-indentation <clang-tidy/checks/readability/misleading-indentation> check to ignore false-positives for line started with empty macro.
• Improved readability-non-const-parameter <clang-tidy/checks/readability/non-const-parameter> check to ignore false-positives in initializer list of record.
• Improved 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 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-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