USAGE: clang-modernize [options] [<sources>...]


Formatting Options:

-format - Enable formatting of code changed by applying replacements.

Use -style to choose formatting style.

-style=<string> - Coding style, currently supports:

LLVM, Google, Chromium, Mozilla, WebKit.

Use -style=\,file\/ to load style configuration from

.clang-format file located in one of the parent directories of the source file (or current directory for stdin). Use -style="{key: value, ...}" to set specific parameters, e.g.:

  • -style="{BasedOnStyle: llvm, IndentWidth: 8}"

-style-config=<string> - Path to a directory containing a .clang-format file

describing a formatting style to use for formatting code when -style=\,file\/.

Inclusion/Exclusion Options: -exclude=<string> - Comma-separated list of paths that can not be transformed -exclude-from=<filename> - File containing a list of paths that can not be transformed -include=<string> - Comma-separated list of paths to consider to be transformed -include-from=<filename> - File containing a list of paths to consider to be transformed

Modernizer Options: -final-syntax-check - Check for correct syntax after applying transformations

-for-compilers=<string> - Select transforms targeting the intersection of

language features supported by the given compilers. Takes a comma-separated list of <compiler>-<version>.

<compiler> can be any of: clang, gcc, icc, msvc

<version> is <major>[.<minor>] -help - Display available options (-help-hidden for more) -help-list - Display list of available options (-help-list-hidden for more) -perf=<directory name> - Capture performance data and output to specified directory. Default: ./migrate_perf -risk - Select a maximum risk level:


- Only safe transformations


- Enable transformations that might change semantics (default)


- Enable transformations that are likely to change semantics -summary - Print transform summary -version - Display the version of this program

Serialization Options:

-serialize-dir=<string> - Path to an existing directory in which to write

serialized replacements. Default behaviour is to write to a temporary directory. -serialize-replacements - Serialize translation unit replacements to disk instead of changing files.

Transforms: -add-override - Make use of override specifier where possible -loop-convert - Make use of range-based for loops where possible -pass-by-value - Pass parameters by value where possible -replace-auto_ptr - Replace std::auto_ptr (deprecated) by std::unique_ptr (EXPERIMENTAL) -use-auto - Use of 'auto' type specifier -use-nullptr - Make use of nullptr keyword where possible

Transforms' options: -override-macros - Detect and use macros that expand to the 'override' keyword. -user-null-macros=<string> - Comma-separated list of user-defined macro names that behave like NULL

-p <build-path> is used to read a compile command database.

  • For example, it can be a CMake build directory in which a file named compile_commands.json exists (use -DCMAKE_EXPORT_COMPILE_COMMANDS=\,ON\/ CMake option to get this output). When no build path is specified, a search for compile_commands.json will be attempted through all parent paths of the first input file . See: for an example of setting up Clang Tooling on a source tree.

<source0> ... specify the paths of source files. These paths are

  • looked up in the compile command database. If the path of a file is absolute, it needs to point into CMake's source tree. If the path is relative, the current working directory needs to be in the CMake source tree and the file must be in a subdirectory of the current working directory. "./" prefixes in the relative files will be automatically removed, but the rest of a relative path must be a suffix of a path in the compile command database.


Apply all transforms on a file that doesn't require compilation arguments:

  • clang-modernize file.cpp

Convert for loops to ranged-based for loops for all files in the compilation database that belong in a project subtree and then reformat the code automatically using the LLVM style:

  • clang-modernize -p build/path -include project/path -format -loop-convert

Make use of both nullptr and the override specifier, using git ls-files:

  • git ls-files '*.cpp' | xargs -I{} clang-modernize -p build/path \ -use-nullptr -add-override -override-macros {}

Apply all transforms supported by both clang >= 3.0 and gcc >= 4.7 to foo.cpp and any included headers in bar:

  • clang-modernize -for-compilers=\,clang-3\/.0,gcc-4.7 foo.cpp \ -include bar -- -std=\,c\/++11 -Ibar

RELATED TO clang-modernize-3.4…

The full documentation for clang-modernize is maintained as a Texinfo manual. If the info and clang-modernize programs are properly installed at your site, the command

  • info clang-modernize

should give you access to the complete manual.