[clang-tidy] [With reproducible example] Erroneous rule "llvm-header-guard" since v21.0.0

[Spixmaster]

All my header guards raise issues now which never was the case before. The following example file is called constant.hpp. See the warning in line 2.

#ifndef CONSTANT_HPP
#define CONSTANT_HPP //code/includes outside of area guarded by header guard; consider moving it [llvm-header-guard]

#include <string>

namespace constant
{
    //Variables
    /**
     * @var name
     * @brief Programme name.
     */
    extern const std::string name;
    /**
     * @var release
     * @brief Release date of the version.
     */
    extern const std::string release;
    /**
     * @var version
     * @brief Version.
     */
    extern const std::string version;

    //Functions
    /**
     * @brief Creates the programme name in lower case.
     * @return Programme name in lower case.
     */
    std::string name_lower_case();
} //namespace constant

#endif

[llvmbot]

@llvm/issue-subscribers-clang-tidy

Author: Matheus Gabriel Werny (Spixmaster)

All my header guards raise issues now which never was the case before. See the warning in line 2.

#ifndef CONSTANT_HPP
#define CONSTANT_HPP //code/includes outside of area guarded by header guard; consider moving it [llvm-header-guard]

#include <string>

namespace constant
{
    //Variables
    /**
     * @<!-- -->var name
     * @<!-- -->brief Programme name.
     */
    extern const std::string name;
    /**
     * @<!-- -->var release
     * @<!-- -->brief Release date of the version.
     */
    extern const std::string release;
    /**
     * @<!-- -->var version
     * @<!-- -->brief Version.
     */
    extern const std::string version;

    //Functions
    /**
     * @<!-- -->brief Creates the programme name in lower case.
     * @<!-- -->return Programme name in lower case.
     */
    std::string name_lower_case();
} //namespace constant

#endif

[carlosgalvezp]

Is your project part of the llvm project? If not, you should probably disable the llvm checks.

[vbvictor]

Is your project part of the llvm project? If not, you should probably disable the llvm checks.

It still could use LLVM header-guard style thought. I don't remember that we added anything to llvm-header-guard check. To proceed further, please share reproduction instructions (probably small project).

[Spixmaster]

My project is not part of LLVM. I still want to follow the guideline though.

I was able to reproduce. Save the files with their stated paths.

Run the following commands then to reproduce.

mkdir build
cd build/
cmake ..
make
cd ..
clang-tidy --config-file=./clang-tidy.yaml -p ./build/ ./include/constant.hpp
50715 warnings generated.
/home/matheus/programmieren/c++/tmp/include/constant.hpp:2:9: warning: code/includes outside of area guarded by header guard; consider moving it [llvm-header-guard]
    2 | #define CONSTANT_HPP
      |         ^
Suppressed 50714 warnings (50714 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.

clang-format.yaml:

---
# BasedOnStyle

AccessModifierOffset: -4
AlignAfterOpenBracket: Align
AlignArrayOfStructures: Left
AlignConsecutiveAssignments: false
AlignConsecutiveBitFields: false
AlignConsecutiveDeclarations: false
AlignConsecutiveMacros: false
AlignEscapedNewlines: DontAlign
AlignOperands: AlignAfterOperator
AlignTrailingComments: false
AllowAllArgumentsOnNextLine: false
AllowAllParametersOfDeclarationOnNextLine: false
AllowShortBlocksOnASingleLine: Never
AllowShortCaseLabelsOnASingleLine: false
AllowShortEnumsOnASingleLine: false
AllowShortFunctionsOnASingleLine: None
AllowShortIfStatementsOnASingleLine: Never
AllowShortLambdasOnASingleLine: None
AllowShortLoopsOnASingleLine: false
AlwaysBreakAfterReturnType: None
AlwaysBreakBeforeMultilineStrings: false
AlwaysBreakTemplateDeclarations: true
AttributeMacros: []
BinPackArguments: true
BinPackParameters: true
BitFieldColonSpacing: Both
BraceWrapping:
  AfterCaseLabel: true
  AfterClass: true
  AfterControlStatement: Always
  AfterEnum: true
  AfterExternBlock: true
  AfterFunction: true
  AfterNamespace: true
  AfterObjCDeclaration: true
  AfterStruct: true
  AfterUnion: true
  BeforeCatch: true
  BeforeElse: true
  BeforeLambdaBody: true
  BeforeWhile: true
  IndentBraces: false
  SplitEmptyFunction: false
  SplitEmptyNamespace: false
  SplitEmptyRecord: false
BreakAfterJavaFieldAnnotations: true
# BreakArrays: false - TODO Not available yet.
BreakBeforeBinaryOperators: None
BreakBeforeBraces: Custom
BreakBeforeConceptDeclarations: true
BreakBeforeTernaryOperators: false
BreakConstructorInitializers: AfterColon
BreakInheritanceList: AfterColon
BreakStringLiterals: true
ColumnLimit: 120
CommentPragmas: ^@
CompactNamespaces: true
ConstructorInitializerIndentWidth: 4
ContinuationIndentWidth: 2
Cpp11BracedListStyle: true
DeriveLineEnding: false
DerivePointerAlignment: false
DisableFormat: false
EmptyLineAfterAccessModifier: Never
EmptyLineBeforeAccessModifier: Always
ExperimentalAutoDetectBinPacking: false
FixNamespaceComments: true
ForEachMacros: []
IfMacros: []
IncludeBlocks: Regroup
IncludeCategories:
  - CaseSensitive: false
    Priority: 1
    Regex: ^<
  - CaseSensitive: false
    Priority: 2
    Regex: ^"
# IncludeIsMainRegex
# IncludeIsMainSourceRegex
IndentAccessModifiers: false
IndentCaseBlocks: false
IndentCaseLabels: true
IndentExternBlock: AfterExternBlock
IndentGotoLabels: true
IndentPPDirectives: AfterHash
IndentRequiresClause: false
IndentWidth: 4
IndentWrappedFunctionNames: true
InsertBraces: true
InsertTrailingCommas: None
JavaImportGroups: []
JavaScriptQuotes: Double
JavaScriptWrapImports: true
KeepEmptyLinesAtTheStartOfBlocks: false
LambdaBodyIndentation: Signature
# Language
# MacroBlockBegin
# MacroBlockEnd
MaxEmptyLinesToKeep: 1
NamespaceIndentation: All
NamespaceMacros: []
ObjCBinPackProtocolList: Always
ObjCBlockIndentWidth: 4
ObjCBreakBeforeNestedBlockParam: false
ObjCSpaceAfterProperty: true
ObjCSpaceBeforeProtocolList: true
PackConstructorInitializers: BinPack
PenaltyBreakAssignment: 90
PenaltyBreakBeforeFirstCallParameter: 50
PenaltyBreakComment: 20
PenaltyBreakFirstLessLess: 70
PenaltyBreakOpenParenthesis: 80
PenaltyBreakString: 40
PenaltyBreakTemplateDeclaration: 30
PenaltyExcessCharacter: 100
PenaltyIndentedWhitespace: 10
PenaltyReturnTypeOnItsOwnLine: 60
PointerAlignment: Right
PPIndentWidth: -1
QualifierAlignment: Custom
QualifierOrder: [inline, static, constexpr, const, volatile, restrict, type]
# RawStringFormats
ReferenceAlignment: Right
ReflowComments: true
RemoveBracesLLVM: false
# RemoveSemicolon: true - TODO Not available yet.
RequiresClausePosition: WithPreceding
SeparateDefinitionBlocks: Always
ShortNamespaceLines: 0
SortIncludes: CaseInsensitive
SortJavaStaticImport: Before
SortUsingDeclarations: true
SpaceAfterCStyleCast: true
SpaceAfterLogicalNot: true
SpaceAfterTemplateKeyword: false
SpaceAroundPointerQualifiers: Default
SpaceBeforeAssignmentOperators: true
SpaceBeforeCaseColon: false
SpaceBeforeCpp11BracedList: true
SpaceBeforeCtorInitializerColon: true
SpaceBeforeInheritanceColon: true
SpaceBeforeParens: Custom
SpaceBeforeParensOptions:
  AfterControlStatements: false
  AfterForeachMacros: false
  AfterFunctionDeclarationName: false
  AfterFunctionDefinitionName: false
  AfterIfMacros: false
  AfterOverloadedOperator: false
  AfterRequiresInClause: false
  AfterRequiresInExpression: false
  BeforeNonEmptyParentheses: false
SpaceBeforeRangeBasedForLoopColon: true
SpaceBeforeSquareBrackets: false
SpaceInEmptyBlock: false
SpaceInEmptyParentheses: false
SpacesBeforeTrailingComments: 1
SpacesInAngles: false
SpacesInConditionalStatement: false
SpacesInContainerLiterals: false
SpacesInCStyleCastParentheses: false
SpacesInLineCommentPrefix:
  Maximum: 0
  Minimum: 0
SpacesInParentheses: false
SpacesInSquareBrackets: false
Standard: Latest
StatementAttributeLikeMacros: []
StatementMacros: []
TabWidth: 4
TypenameMacros: []
UseCRLF: false
UseTab: Never
WhitespaceSensitiveMacros: []

clang-tidy.yaml:

---
# "google-readability-namespace-comments" needs to be removed as it is an alias for "llvm-namespace-comment" and
# thus prevents fixing.
Checks: "*, -abseil-string-find-str-contains, -altera-id-dependent-backward-branch, -altera-unroll-loops, -bugprone-branch-clone,
  -bugprone-easily-swappable-parameters, -bugprone-suspicious-missing-comma, -bugprone-unused-raii, -cert-err58-cpp, -cppcoreguidelines-avoid-magic-numbers,
  -fuchsia-default-arguments-calls, -fuchsia-default-arguments-declarations, -fuchsia-overloaded-operator, -fuchsia-statically-constructed-objects,
  -google-readability-function-size, -google-readability-namespace-comments, -google-readability-todo, -hicpp-function-size,
  -hicpp-named-parameter, -hicpp-use-auto, -llvm-else-after-return, -llvm-include-order, -llvmlibc-callee-namespace, -llvmlibc-implementation-in-namespace,
  -llvmlibc-inline-function-decl, -llvmlibc-restrict-system-libc-headers, -misc-no-recursion, -modernize-loop-convert, -modernize-use-auto,
  -modernize-use-designated-initializers, -modernize-use-nodiscard, -modernize-use-trailing-return-type, -openmp-exception-escape,
  -performance-inefficient-string-concatenation, -readability-else-after-return, -readability-function-cognitive-complexity,
  -readability-function-size, -readability-identifier-length, -readability-magic-numbers, -readability-named-parameter"
FormatStyle: ${XDG_CONFIG_HOME}/clang/clang-format.yaml

CMakeLists.txt:

cmake_minimum_required(VERSION "4.0.0")

if("${CMAKE_BINARY_DIR}/" STREQUAL "${CMAKE_SOURCE_DIR}/")
    message(FATAL_ERROR "In-source builds are not allowed!")
endif()

# Options
option(ARGO_BUILD_DOCUMENTATION "Build the documentation." OFF)
option(ARGO_BUILD_TESTS "Build the tests." OFF)

# General
if(NOT ${ARGO_BUILD_TESTS})
    project("argo")
else()
    project("argo-tests")
endif()

set(CMAKE_CXX_STANDARD 23)
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

# Dependencies

# Target
set(SRCS "${CMAKE_SOURCE_DIR}/src/constant.cpp")

if(${ARGO_BUILD_TESTS})

else()
    list(APPEND SRCS "${CMAKE_SOURCE_DIR}/src/main.cpp")
endif()

if(NOT ${ARGO_BUILD_TESTS})
    add_executable("${PROJECT_NAME}" "${SRCS}")
else()
    add_executable("${PROJECT_NAME}" "${SRCS}")
    add_test(NAME "${PROJECT_NAME}" COMMAND "${PROJECT_NAME}")
    enable_testing()
    include("CTest")
endif()

# Headers
target_include_directories("${PROJECT_NAME}" PUBLIC "${CMAKE_SOURCE_DIR}/include/")

# Link libraries

# Debugging options
if(${ARGO_BUILD_TESTS})
    target_compile_options("${PROJECT_NAME}" PUBLIC "-g")
endif()

# Optimisation options
if(NOT ${ARGO_BUILD_TESTS})
    target_compile_options("${PROJECT_NAME}" PUBLIC "-O3")
else()
    target_compile_options("${PROJECT_NAME}" PUBLIC "-O0")
endif()

# Preprocessor options
target_compile_options("${PROJECT_NAME}" PUBLIC "-MD")
target_compile_options("${PROJECT_NAME}" PUBLIC "-MP")

# Programme instrumentation options
if(${ARGO_BUILD_TESTS})
    target_compile_options("${PROJECT_NAME}" PUBLIC "--coverage")
endif()

# Warning options
target_compile_options("${PROJECT_NAME}" PUBLIC "-Wall")
target_compile_options("${PROJECT_NAME}" PUBLIC "-Wextra")

# Other needed processes

# Documentation

# Target dependencies

# Installation
install(
    TARGETS "${PROJECT_NAME}"
    ARCHIVE
    BUNDLE CXX_MODULES_BMI
    FRAMEWORK
    LIBRARY
    OBJECTS
    PRIVATE_HEADER
    PUBLIC_HEADER
    RESOURCE
    RUNTIME)

include/constant.hpp:

#ifndef CONSTANT_HPP
#define CONSTANT_HPP

#include <string>

namespace constant
{
    //Variables
    /**
     * @var name
     * @brief Programme name.
     */
    extern const std::string name;
    /**
     * @var release
     * @brief Release date of the version.
     */
    extern const std::string release;
    /**
     * @var version
     * @brief Version.
     */
    extern const std::string version;

    //Functions
    /**
     * @brief Creates the programme name in lower case.
     * @return Programme name in lower case.
     */
    std::string name_lower_case();
} //namespace constant

#endif

src/constant.cpp:

#include "constant.hpp"

#include <algorithm>
#include <cctype>
#include <cstdint>
#include <string>

namespace constant
{
    const std::string name = "Argo";
    const std::string release = "31.Jan.2025";
    const std::string version = "2.3.0";

    std::string name_lower_case()
    {
        std::string tmp = name;
        std::ranges::transform(
          tmp.cbegin(), tmp.cend(), tmp.begin(),
          [](const std::uint8_t &ch) -> std::int32_t
          {
              return std::tolower(ch);
          });

        return tmp;
    }
} //namespace constant

src/main.cpp:

#include <cstdint>
#include <cstdlib>

int main(std::int32_t argc, char **argv)
{
    return EXIT_SUCCESS;
}

[vbvictor]

Hi, I ran this locally and indeed 19,20 version don't fire and 21st fire.

P.S. please don't use cmake_minimum_required(VERSION "4.0.0") unless really required. Your CMake works fine with 3.x.x version, and 4.x.x could be installed from apt yet.

[Spixmaster]

Thanks for the confirmation!

This is a personal project. The required CMake version thus only matters for me.