Extra Clang Tools 24.0.0git (In-Progress) Release Notes#

Written by the LLVM Team

Warning

These are in-progress notes for the upcoming Extra Clang Tools 24 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 24.0.0git. 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 24.0.0git?#

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#

Potentially Breaking Changes#

  • The deprecated zircon clang-tidy module has been removed. Users of zircon-temporary-objects should migrate to fuchsia-temporary-objects.

  • In 22nd release, The clang-tidy/ClangTidyModuleRegistry.h header was deprecated. All of the symbols it used to define were moved into clang-tidy/ClangTidyModule.h. The deprecated header has been removed in this release.

Improvements to clangd#

Inlay hints#

Diagnostics#

  • Query-based custom clang-tidy checks can now be enabled with the Diagnostics.ClangTidy.ExperimentalCustomChecks clangd configuration option. Custom checks are subject to FastCheckFilter, and therefore require FastCheckFilter: Loose or None to run.

Semantic Highlighting#

Compile flags#

Hover#

  • The type a decltype resolves to is now also shown for composite types, e.g. decltype(x)& is displayed as int&. Qualifiers applied to a decltype are no longer dropped, so const decltype(x) is displayed as const int rather than int.

Code completion#

  • Parameters declared with a decltype are now displayed as the type the decltype resolves to, e.g. set_x(int val) rather than set_x(decltype(x) val).

Code actions#

  • clangd now applies clang-tidy fix-it post-processing before exposing fixes.

  • The Extract to function tweak is now offered for selections consisting of a single expression-statement (e.g. a lone function call or an overloaded operator call such as stream << 42;), which it previously refused to extract.

  • The Extract to function tweak is now also available in C files, where it previously always refused to apply. Captured variables are passed by value when possible, and otherwise via a pointer parameter, since C has no references.

Signature help#

  • Parameters declared with a decltype are now displayed as the type the decltype resolves to, as for code completion.

Cross-references#

Objective-C#

Miscellaneous#

  • Fixed clangd-indexer --format=yaml emitting invalid YAML when indexing C++20 concepts. (#206875)

  • clangd-indexer now reads clangd configuration files (.clangd and the user config) by default. Pass --enable-config=false to restore the previous behavior.

  • Added support for loading dynamic plugins via the -load command-line option.

Improvements to clang-doc#

Improvements to clang-query#

Improvements to clang-tidy#

  • Improved check_clang_tidy.py by adding support of -std=cXX-or-earlier values, mirroring the existing -std=cXX-or-later. New construct expands to the given standard and every earlier one.

  • On Windows, clang-tidy will now better match mixes of forwards and backwards slashes when using the --line-filter option. This also improves piping from git to clang-tidy-diff.py, where slashes will now be automatically normalized.

New checks#

  • New llvm-invalid-regex-pattern check.

    Detects malformed regex patterns defined in a single string literal.

  • New modernize-use-if-consteval check.

    Replaces direct std::is_constant_evaluated() checks in if statements with C++23’s if consteval syntax.

  • New modernize-use-to-underlying check.

    Finds casts from a scoped enumeration (enum class) to an integer type and replaces them with a call to std::to_underlying (introduced in C++23).

  • New performance-expensive-value-or check.

    Finds calls to value_or (and alternative spellings valueOr, ValueOr) on optional types where the return type is expensive to copy.

  • New portability-avoid-pragma-comment check.

    Finds uses of #pragma comment and, for lib or linker comments, suggests using the build system for improved portability.

  • New readability-redundant-zero-initializer check.

    Finds explicit zero initializers of arrays that can be replaced with empty braces.

New check aliases#

Changes in existing checks#

  • Improved bugprone-assignment-in-if-condition check by ignoring assignments inside GNU statement expressions unless they form the value of the statement expression.

  • Improved bugprone-easily-swappable-parameters check by no longer emitting empty notes for type aliases when ModelImplicitConversions is enabled.

  • Improved bugprone-implicit-widening-of-multiplication-result check by suggesting a wider type of the same signedness as the original operands, instead of forcing a signed type, when a multiplication of two unsigned operands narrower than int is only signed due to integer promotion.

  • Improved bugprone-macro-parentheses by fixing invalid fixes for macro arguments used as names in alias declarations.

  • Fixed a crash in bugprone-misplaced-operator-in-strlen-in-alloc when checking an array new expression without a size expression.

  • Fixed a crash in bugprone-misplaced-pointer-arithmetic-in-alloc when pointer arithmetic is applied to a non-array new expression whose constructor has no arguments.

  • Fixed a crash in bugprone-pointer-arithmetic-on-polymorphic-object when the pointer points to an incomplete (forward-declared) type.

  • Improved bugprone-redundant-branch-condition check by fixing false positives when the condition variable is changed later in a loop that encloses the inner if.

  • Fixed a crash in bugprone-std-namespace-modification when checking lambda closure types used as template arguments.

  • Improved bugprone-unchecked-optional-access by fixing false positives on bsl::optional and bdlb::NullableValue constructed from a value or returned by bsl::make_optional.

  • Improved cppcoreguidelines-missing-std-forward check by diagnosing unforwarded auto&& parameters in C++20 abbreviated function templates.

  • Improved cppcoreguidelines-pro-type-member-init check by treating std::array the same as built-in arrays when IgnoreArrays option is enabled.

  • Improved cppcoreguidelines-use-enum-class check by omitting unnamed enums from the enum class requirement, as previously the check suggested users an ill-formed fix.

  • Improved cppcoreguidelines-virtual-class-destructor check by emitting the diagnostic and its fix-it notes at the destructor’s location instead of the class name, whenever the destructor is user-declared. The diagnostics are still emitted at the class name for implicitly declared destructors.

  • Improved misc-const-correctness check:

    • Fixed false positives when the pointee is written through a pointer that is incremented, decremented or adjusted with += or -=, such as *p++ = 0.

    • Fixed false positives when the pointee is written through a pointer assignment, such as *(p = q) = 0.

    • No longer diagnoses variables declared with decltype(auto), where the suggested const does not compile.

    • No longer diagnoses parameters of main, whose signature is fixed by the standard.

  • Fixed an infinite loop in misc-multiple-inheritance when checking a class that inherits from itself or has a circular inheritance graph.

  • Improved misc-redundant-expression by fixing false positives in nested expressions involving different macros or a mix of macro and non-macro operands.

  • Fixed a crash in modernize-raw-string-literal on synthetic string literals created for raw user-defined literal operators, such as 12_w.

  • Improved modernize-return-braced-init-list check to no longer rewrite the return value when the constructed type has a std::initializer_list constructor, as the braced form could select a different constructor.

  • Fixed a crash in modernize-use-designated-initializers when analyzing malformed code with nested classes and ambiguous initializer.

  • Improved modernize-use-equals-default check to also capture default constructor with explicit default-initialization of parents.

  • Fixed a crash in modernize-use-noexcept when analyzing malformed template code with an unparsed exception specification.

  • Extend modernize-use-nullptr to turn decltype(nullptr) into std::nullptr_t from <cstdef>.

  • Improved modernize-use-nullptr check to avoid replacing 0 with nullptr in comparisons with ordering types such as std::strong_ordering.

  • Improved modernize-use-ranges check by preserving used output iterator results when replacing output algorithms such as std::copy.

    • Preserved used callable results when replacing std::for_each and structured binding results when replacing algorithms such as std::equal_range.

    • Kept diagnostics but suppressed unsafe fix-its when no safe result-preserving rewrite is available.

  • Improved performance-inefficient-algorithm check to no longer produce a fix with the container or the searched-for value missing, such as .find(43) or s.find(), when either comes from a macro. The value is copied as written rather than with its parentheses stripped, and no fix is offered when an argument covers only part of a macro expansion, as it then has no source text of its own.

  • Improved performance-inefficient-vector-operation by adding the ForRangeLoopClasses to configure container classes that can be used as sources in range-based for loops.

  • Improved performance-no-automatic-move check by no longer warning when returning a variable captured by a lambda or a block, which is never implicitly moved from.

  • Improved performance-prefer-single-char-overloads check to avoid offering fix-its for string literals originating from macro expansions.

  • Improved readability-convert-member-functions-to-static check by fixing a crash when checking a const-qualified method declared with the lifetimebound attribute.

  • Improved readability-enum-initial-value check by adding the AllowReferencedInitialValues to support the INT09-C-EX1 exception, allowing enumerators initialized by referencing another enumerator in the same enum (e.g., last = first).

  • Improved readability-function-cognitive-complexity check by fixing a crash when checking a function declared with the alias attribute.

  • Improved readability-identifier-naming check:

    • Fixed a crash when a class inherits from a forward-declared base class.

    • Fixed a crash when checking forward-declared classes with DefaultHungarianPrefix enabled.

    • Fixed DefaultHungarianPrefix being incorrectly diagnosed as an invalid option.

    • Fixed invalid fixes when renaming parameter packs used in sizeof... expressions.

    • Added the TypedefInheritAnonTagConfig, which checks a typedef or type alias that provides the only name of an otherwise unnamed tag, such as typedef enum {} MyEnum;, against the style configured for that tag kind instead of the typedef or type alias style.

    • Added support for naming lambda init-captures (e.g. [Captured = Var]) via the new LambdaCapture options. Simple, non-init captures continue to follow the naming style of the variable they capture.

    • Added the AllowTrailingUnderscore, which permits a single trailing underscore on any identifier.

  • Improved readability-named-parameter check by ignoring standard tag types (e.g. std::in_place_t, std::allocator_arg_t, std::nothrow_t, iterator tags, lock tags, etc.) that are used exclusively for overload resolution. Added the IgnoredTypes option to allow customizing the set of ignored types.

  • Improved readability-non-const-parameter check by fixing false positives on pointers passed to atomic builtins, whose operands may be written to, such as the expected parameter of atomic_compare_exchange_strong().

  • Improved readability-redundant-parentheses check:

    • Fixed a false positive on the required parentheses of typeof and typeof_unqual operands.

    • Fixed false positives and incorrect fixes caused by synthetic parentheses in reference non-type template parameter uses, __builtin_dump_struct calls, and OpenMP linear clauses.

    • Fixed false positives on parentheses that determine the deduced type in decltype((x)) and in the initializers and return statements of decltype(auto) declarations.

  • Fixed readability-simplify-boolean-expr producing invalid fixes when applying De Morgan’s theorem to overloaded comparison operators.

  • Improved readability-suspicious-call-argument check by fixing the default dist and dst abbreviations of distance not being recognized.

  • Improved readability-trailing-comma check:

    • Fixed false positives on designated initializers, where initializer lists synthesized for intermediate subobjects caused the trailing comma of the enclosing list to be incorrectly rewritten.

    • Ignored preprocessor directives such as #endif that appear immediately before an enum’s closing brace, which previously produced a false positive and a fix-it that inserted a comma after the directive.

    • Fixed a false positive on empty brace initializers of types with default member initializers.

  • Improved readability-use-std-min-max check by fixing spurious trailing semicolons and lost comments when the if body has no braces.

Removed checks#

Miscellaneous#

  • Fixed clang-tidy adding an unwanted blank line when automatically inserting a missing #include, which stopped clang-format and the llvm-include-order check from being able to sort it correctly afterwards.

Improvements to include-fixer#

Improvements to clang-include-fixer#

Improvements to modularize#

Improvements to pp-trace#

Clang-tidy Visual Studio plugin#