title	description
clang-format configuration in MegaLinter	How to use clang-format (configure, ignore files, ignore errors, help & version documentations) to analyze CPP files

clang-format

clang-format is a powerful code formatter for C, C++, Java, JavaScript, JSON, Objective-C, Protobuf, and C# that automatically formats code according to configurable style guidelines. It's part of the LLVM project and provides consistent, automated formatting.

Key Features:

Multi-Language Support: Formats C/C++, Java, JavaScript, JSON, Objective-C, Protobuf, and C# code with language-specific rules
Predefined Styles: Built-in styles including LLVM, Google, Chromium, Mozilla, Microsoft, WebKit, and GNU coding standards
Highly Configurable: Extensive customization options through .clang-format files with hundreds of style parameters
Selective Formatting: Format specific lines, ranges, or regions with precise control over what gets formatted
Git Integration: Built-in tools for formatting only changed lines in git commits and diffs
In-Place Editing: Can modify files directly or output formatted code to stdout

clang-format documentation

Version in MegaLinter: 20.1.8
Visit Official Web Site{target=_blank}
See How to configure clang-format rules{target=_blank}
See How to disable clang-format rules in files{target=_blank}
See Index of problems detected by clang-format{target=_blank}

{target=_blank}

Configuration in MegaLinter

Enable clang-format by adding CPP_CLANG_FORMAT in ENABLE_LINTERS variable
Disable clang-format by adding CPP_CLANG_FORMAT in DISABLE_LINTERS variable
Enable autofixes by adding CPP_CLANG_FORMAT in APPLY_FIXES variable

Variable	Description	Default value
CPP_CLANG_FORMAT_ARGUMENTS	User custom arguments to add in linter CLI call Ex: `-s --foo "bar"`
CPP_CLANG_FORMAT_COMMAND_REMOVE_ARGUMENTS	User custom arguments to remove from command line before calling the linter Ex: `-s --foo "bar"`
CPP_CLANG_FORMAT_FILTER_REGEX_INCLUDE	Custom regex including filter Ex: `(src\|lib)`	Include every file
CPP_CLANG_FORMAT_FILTER_REGEX_EXCLUDE	Custom regex excluding filter Ex: `(test\|examples)`	Exclude no file
CPP_CLANG_FORMAT_CLI_LINT_MODE	Override default CLI lint mode - `file`: Calls the linter for each file - `list_of_files`: Call the linter with the list of files as argument - `project`: Call the linter from the root of the project	`list_of_files`
CPP_CLANG_FORMAT_FILE_EXTENSIONS	Allowed file extensions. `"*"` matches any extension, `""` matches empty extension. Empty list excludes all files Ex: `[".py", ""]`	`[".cpp", ".h", ".cc", ".hpp", ".cxx", ".cu", ".hxx", ".c++", ".hh", ".h++", ".cuh"]`
CPP_CLANG_FORMAT_FILE_NAMES_REGEX	File name regex filters. Regular expression list for filtering files by their base names using regex full match. Empty list includes all files Ex: `["Dockerfile(-.+)?", "Jenkinsfile"]`	Include every file
CPP_CLANG_FORMAT_PRE_COMMANDS	List of bash commands to run before the linter	None
CPP_CLANG_FORMAT_POST_COMMANDS	List of bash commands to run after the linter	None
CPP_CLANG_FORMAT_UNSECURED_ENV_VARIABLES	List of env variables explicitly not filtered before calling CPP_CLANG_FORMAT and its pre/post commands	None
CPP_CLANG_FORMAT_CONFIG_FILE	clang-format configuration file name Use `LINTER_DEFAULT` to let the linter find it	`.clang-format`
CPP_CLANG_FORMAT_RULES_PATH	Path where to find linter configuration file	Workspace folder, then MegaLinter default rules
CPP_CLANG_FORMAT_DISABLE_ERRORS	Run linter but consider errors as warnings	`false`
CPP_CLANG_FORMAT_DISABLE_ERRORS_IF_LESS_THAN	Maximum number of errors allowed	`0`
CPP_CLANG_FORMAT_CLI_EXECUTABLE	Override CLI executable	`['clang-format']`

IDE Integration

Use clang-format in your favorite IDE to catch errors before MegaLinter !

	IDE	Extension Name	Install
	Visual Studio Code	Clang-Format	{target=_blank}
	Emacs	clang-format	Visit Web Site{target=_blank}

MegaLinter Flavors

This linter is available in the following flavors

	Flavor	Description	Embedded linters	Info
	all	Default MegaLinter Flavor	127
	c_cpp	Optimized for pure C/C++ projects	56

Behind the scenes

How are identified applicable files

File extensions: .cpp, .h, .cc, .hpp, .cxx, .cu, .hxx, .c++, .hh, .h++, .cuh

How the linting is performed

clang-format is called once with the list of files as arguments (list_of_files CLI lint mode)

Example calls

clang-format --Werror --dry-run myfile.cpp

Help content

OVERVIEW: A tool to format C/C++/Java/JavaScript/JSON/Objective-C/Protobuf/C# code.

If no arguments are specified, it formats the code from standard input
and writes the result to the standard output.
If <file>s are given, it reformats the files. If -i is specified
together with <file>s, the files are edited in-place. Otherwise, the
result is written to the standard output.

USAGE: clang-format [options] [@<file>] [<file> ...]

OPTIONS:

Clang-format options:

  --Werror                       - If set, changes formatting warnings to errors
  --Wno-error=<value>            - If set, don't error out on the specified warning type.
    =unknown                     -   If set, unknown format options are only warned about.
                                     This can be used to enable formatting, even if the
                                     configuration contains unknown (newer) options.
                                     Use with caution, as this might lead to dramatically
                                     differing format depending on an option being
                                     supported or not.
  --assume-filename=<string>     - Set filename used to determine the language and to find
                                   .clang-format file.
                                   Only used when reading from stdin.
                                   If this is not passed, the .clang-format file is searched
                                   relative to the current working directory when reading stdin.
                                   Unrecognized filenames are treated as C++.
                                   supported:
                                     CSharp: .cs
                                     Java: .java
                                     JavaScript: .js .mjs .cjs .ts
                                     Json: .json
                                     Objective-C: .m .mm
                                     Proto: .proto .protodevel
                                     TableGen: .td
                                     TextProto: .txtpb .textpb .pb.txt .textproto .asciipb
                                     Verilog: .sv .svh .v .vh
  --cursor=<uint>                - The position of the cursor when invoking
                                   clang-format from an editor integration
  --dry-run                      - If set, do not actually make the formatting changes
  --dump-config                  - Dump configuration options to stdout and exit.
                                   Can be used with -style option.
  --fail-on-incomplete-format    - If set, fail with exit code 1 on incomplete format.
  --fallback-style=<string>      - The name of the predefined style used as a
                                   fallback in case clang-format is invoked with
                                   -style=file, but can not find the .clang-format
                                   file to use. Defaults to 'LLVM'.
                                   Use -fallback-style=none to skip formatting.
  --ferror-limit=<uint>          - Set the maximum number of clang-format errors to emit
                                   before stopping (0 = no limit).
                                   Used only with --dry-run or -n
  --files=<filename>             - A file containing a list of files to process, one per line.
  -i                             - Inplace edit <file>s, if specified.
  --length=<uint>                - Format a range of this length (in bytes).
                                   Multiple ranges can be formatted by specifying
                                   several -offset and -length pairs.
                                   When only a single -offset is specified without
                                   -length, clang-format will format up to the end
                                   of the file.
                                   Can only be used with one input file.
  --lines=<string>               - <start line>:<end line> - format a range of
                                   lines (both 1-based).
                                   Multiple ranges can be formatted by specifying
                                   several -lines arguments.
                                   Can't be used with -offset and -length.
                                   Can only be used with one input file.
  -n                             - Alias for --dry-run
  --offset=<uint>                - Format a range starting at this byte offset.
                                   Multiple ranges can be formatted by specifying
                                   several -offset and -length pairs.
                                   Can only be used with one input file.
  --output-replacements-xml      - Output replacements as XML.
  --qualifier-alignment=<string> - If set, overrides the qualifier alignment style
                                   determined by the QualifierAlignment style flag
  --sort-includes                - If set, overrides the include sorting behavior
                                   determined by the SortIncludes style flag
  --style=<string>               - Set coding style. <string> can be:
                                   1. A preset: LLVM, GNU, Google, Chromium, Microsoft,
                                      Mozilla, WebKit.
                                   2. 'file' to load style configuration from a
                                      .clang-format file in one of the parent directories
                                      of the source file (for stdin, see --assume-filename).
                                      If no .clang-format file is found, falls back to
                                      --fallback-style.
                                      --style=file is the default.
                                   3. 'file:<format_file_path>' to explicitly specify
                                      the configuration file.
                                   4. "{key: value, ...}" to set specific parameters, e.g.:
                                      --style="{BasedOnStyle: llvm, IndentWidth: 8}"
  --verbose                      - If set, shows the list of processed files

Generic Options:

  --help                         - Display available options (--help-hidden for more)
  --help-list                    - Display list of available options (--help-list-hidden for more)
  --version                      - Display the version of this program

Installation on mega-linter Docker image

APK packages (Linux):
- clang20-extra-tools

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