Extra Clang Tools 18.1.0rc Release Notes¶
Written by the LLVM Team
Introduction¶
This document contains the release notes for the Extra Clang Tools, part of the Clang release 18.1.0rc. 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 18.1.0rc?¶
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, bugprone-reserved-identifier, and 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 check.
Detects unsafe or redundant two-step casting operations involving
void*
.New bugprone-chained-comparison check.
Check detects chained comparison operators that can lead to unintended behavior or logical errors.
New 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 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 check.
Detects incorrect usages of
std::enable_if
that don’t name the nestedtype
type.New bugprone-multi-level-implicit-pointer-conversion check.
Detects implicit conversions between pointers of different levels of indirection.
New 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 check.
Warns when a local non trivial variable is unused within a function.
New 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 check.
Ensure that the result of
std::remove
,std::remove_if
andstd::unique
are not ignored according to rule 17.5.1.New 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 check.
Replace
enable_if
with C++20 requires clauses.New modernize-use-starts-ends-with check.
Checks whether a
find
orrfind
result is compared with 0 and suggests replacing withstarts_with
when the method exists in the class. Notably, this will work withstd::string
andstd::string_view
.New 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 check.
Recommends the smallest possible underlying type for an
enum
orenum
class based on the range of its enumerators.New readability-avoid-nested-conditional-operator check.
Identifies instances of nested conditional operators in the code.
New readability-avoid-return-with-void-value check.
Finds return statements with
void
values used within functions withvoid
result types.New readability-redundant-casting check.
Detects explicit type casting operations that involve the same source and destination types, and subsequently recommend their removal.
New readability-redundant-inline-specifier check.
Detects redundant
inline
specifiers on function and variable declarations.New 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 cppcoreguidelines-macro-to-enum to modernize-macro-to-enum was added.
Changes in existing checks¶
Improved abseil-string-find-startswith check to also consider
std::basic_string_view
in addition tostd::basic_string
by default.Improved 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 check to support functional casting during type conversions at variable initialization, now with improved compatibility for C++17 and later versions.
Improved bugprone-exception-escape check by extending the default check function names to include
iter_swap
anditer_move
.Improved bugprone-implicit-widening-of-multiplication-result check to correctly emit fixes.
Improved bugprone-lambda-function-name check by adding option IgnoreMacros to ignore warnings in macros.
Improved bugprone-non-zero-enum-to-bool-conversion check by eliminating false positives resulting from direct usage of bitwise operators.
Improved bugprone-reserved-identifier check, so that it does not warn on macros starting with underscore and lowercase letter.
Improved bugprone-sizeof-expression check diagnostics to precisely highlight specific locations, providing more accurate guidance.
Improved bugprone-unchecked-optional-access check, so that it does not crash during handling of optional values.
Improved bugprone-undefined-memory-manipulation check to support fixed-size arrays of non-trivial types.
Improved bugprone-unused-return-value check diagnostic message, added support for detection of unused results when cast to non-
void
type. Casting tovoid
no longer suppresses issues by default, control this behavior with the new AllowCastToVoid option.Improved cppcoreguidelines-avoid-non-const-global-variables check to ignore
static
variables declared within the scope ofclass
/struct
.Improved 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-missing-std-forward check to address false positives in the capture list and body of lambdas.
Improved 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 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 cppcoreguidelines-pro-bounds-array-to-pointer-decay check to ignore predefined expression (e.g.,
__func__
, …).Improved cppcoreguidelines-pro-bounds-constant-array-index check to perform checks on derived classes of
std::array
.Improved cppcoreguidelines-pro-type-const-cast check to ignore casts to
const
orvolatile
type (controlled by StrictMode option) and casts in implicitly invoked code.Improved cppcoreguidelines-pro-type-member-init check to ignore dependent delegate constructors.
Improved 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 check to ignore false-positives in unevaluated context (e.g.,
decltype
,sizeof
, …).Improved 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 google-readability-casting check to ignore constructor calls disguised as functional casts.
Improved google-runtime-int check to ignore false positives on user defined-literals.
Improved llvm-namespace-comment check to provide fixes for
inline
namespaces in the same format as clang-format.Improved llvmlibc-callee-namespace to support customizable namespace. This matches the change made to implementation in namespace.
Improved 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 to properly ignore implicit functions, such as struct constructors, and explicitly deleted functions.
Improved 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 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 check to ignore false-positives in unevaluated context (e.g.,
decltype
).Improved misc-static-assert check to ignore false-positives when referring to non-
constexpr
variables in non-unevaluated context.Improved misc-unused-using-decls check to avoid false positive when using in elaborated type and only check C++ files.
Improved modernize-avoid-bind check to not emit a
return
for fixes when the function returnsvoid
and to provide valid fixes for cases involving bound C++ operators.Improved modernize-loop-convert to support for-loops with iterators initialized by free functions like
begin
,end
, orsize
and avoid crash for array of dependent array and non-dereferenceable builtin types used as iterators.Improved modernize-make-shared check to support
std::shared_ptr
implementations that inherit thereset
method from a base class.Improved modernize-return-braced-init-list check to ignore false-positives when constructing the container with
count
copies of elements with valuevalue
.Improved modernize-use-auto to avoid create incorrect fix hints for pointer to array type and pointer to function type.
Improved modernize-use-emplace to not replace aggregates that
emplace
cannot construct with aggregate initialization.Improved modernize-use-equals-delete check to ignore false-positives when special member function is actually used or implicit.
Improved modernize-use-nullptr check by adding option IgnoredTypes that can be used to exclude some pointer types.
Improved modernize-use-std-print check to accurately generate fixes for reordering arguments.
Improved modernize-use-using check to fix function pointer and forward declared
typedef
correctly. Added option IgnoreExternC to ignoretypedef
declaration inextern "C"
scope.Improved performance-faster-string-find check to properly escape single quotes.
Improved performance-for-range-copy check to handle cases where the loop variable is a structured binding.
Improved performance-noexcept-move-constructor to better handle conditional
noexcept
expressions, eliminating false-positives.Improved 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 readability-braces-around-statements check to ignore false-positive for
if constexpr
in lambda expression.Improved readability-avoid-const-params-in-decls diagnostics to highlight the
const
locationImproved readability-container-contains to correctly handle integer literals with suffixes in fix-its.
Improved readability-container-size-empty check to detect comparison between string and empty string literals and support
length()
method as an alternative tosize()
. Resolved false positives tied to negative values from size-like methods, and one triggered by size checks below zero.Improved readability-function-size check configuration to use none rather than -1 to disable some parameters.
Improved 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
andunion
in C, while also incorporating support for theLeading_upper_snake_case
naming convention. The handling oftypedef
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++20concept
declarations.Camel_Snake_Case
andcamel_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 publicstruct
/union
members.Improved 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 readability-misleading-indentation check to ignore false-positives for line started with empty macro.
Improved readability-non-const-parameter check to ignore false-positives in initializer list of record.
Improved readability-redundant-member-init check to now also detect redundant in-class initializers.
Improved readability-simplify-boolean-expr check by adding the new option IgnoreMacros that allows to ignore boolean expressions originating from expanded macros.
Improved readability-simplify-subscript-expr check by extending the default value of the Types option to include
std::span
.Improved 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…