wpiformat 2026.55

Linters and formatters for ensuring WPILib's source code conforms to its style guide

wpiformat

Provides linters and formatters for ensuring WPILib's C++, Java, and Python code conform to its style guide. WPILib uses a variant of the Google style guides.

Project Setup

To use these tools with a new project, copy .wpiformat, and .wpiformat-license from the examples folder into the project and create a new .clang-format file based on the desired C/C++ style.

.wpiformat

wpiformat checks the current directory for the .wpiformat file. If one doesn't exist, all parent directories are tried as well. This file contains groups of filename regular expressions.

groupName {
  regex_here
}

The regexes are matched using re.search(), so they don't have to match the whole filename.

Empty config groups can be omitted. Directory separators must be "/", not "\". During processing, they will be replaced internally with an os.sep that is automatically escaped for regexes.

See the .wpiformat file in the docs/examples directory for all possible groups.

Specifying C/C++ files to format

The cHeaderFileInclude group specifies C headers to format, the cppHeaderFileInclude group specifies C++ headers to format, and the cppSrcFileInclude group specifies C++ source files to format. It's common to match just the file extension like so: \.hpp$.

Ignoring files

There are two groups of regexes which prevent tasks (i.e., formatters and linters) from running on matching files:

• generatedFileExclude (generated files)
• modifiableFileExclude (modifiable files)

Generated files should not be modified by the user; if they are, wpiformat will emit warnings. No warnings are emitted for modifications to modifiable files.

All files ignored by patterns in a repository's .gitignore file are considered modifiable files. Exclusion groups take precedence over inclusion groups.

License update exclusion

Filenames matching regexes in the group licenseUpdateExclude will be skipped by the license header update task.

Include guards

Valid include guard patterns have the following properties:

• Use capital letters
• Start with the repository name
• Include the path to the file and the filename itself
• Have directory separators and hyphens replaced with underscores
• Have a trailing underscore

The path to the file starts from the repository root by default. Other paths, such as include directories, can be specified in the includeGuardRoots group. If a path matches, that string will be truncated from the include guard pattern.

For example, given a file at allwpilib/src/main/native/include/wpiutil/support/ConcurrentQueue.h and an include path of src/main/native/include/, the resulting include guard would be ALLWPILIB_WPIUTIL_SUPPORT_CONCURRENTQUEUE_H_.

The repoRootNameOverride group allows one to override the repository name used in include guards. This is useful for giving subprojects within one repository different repository roots in their include guards. Only specify one name in this group because subsequent names will be ignored.

.wpiformat-license

This file contains the license header template. It should contain Copyright (c) followed by the company name and the string {year}. See the .wpiformat-license file in the docs/examples directory.

wpiformat checks the currently processed file's directory for a .wpiformat file first and traverses up the directory tree if one isn't found. This allows templates which are closer to the processed file to override a project's main template.

License header semantics

The license header is always at the beginning of the file and ends after two newlines. If there isn't one, or it doesn't contain the required copyright contents, wpiformat inserts a new one containing the current year.

.wpiformat-license special variables

{year} is replaced with a year range from the earliest copyright year in the file to the current year. If the earliest year is the current year, only that year will be written.

{padding} is optional and represents an expanding space which pads the line to 80 columns. Multiple instances of {padding} on the same line share the padding equally.

{filename} is optional and represents the current file's path relative to the Git repository root. Path separators are normalized to forward slashes on all platforms.