clang_tidy

A wrapper library and program that runs clang_tidy on the Flutter engine repo.

# Assuming you are in the `flutter` root of the engine repo.
dart ./tools/clang_tidy/bin/main.dart

By default, the linter runs over modified¹ files in the latest² build of the engine.

A subset of checks can also be fixed automatically by passing --fix:

dart ./tools/clang_tidy/bin/main.dart --fix

To configure what lints are enabled, see .clang-tidy.

💡 TIP: If you're looking for the git pre-commit hook configuration, see githooks.

Advanced Usage

Some common use cases are described below, or use --help to see all options.

Run with checks added or removed

To run adding a check not specified in .clang-tidy:

dart ./tools/clang_tidy/bin/main.dart --checks="<check-name-to-run>"

It's possible also to use wildcards to add multiple checks:

dart ./tools/clang_tidy/bin/main.dart --checks="readability-*"

To remove a specific check:

dart ./tools/clang_tidy/bin/main.dart --checks="-<check-name-to-remove>"

To remove multiple checks:

dart ./tools/clang_tidy/bin/main.dart --checks="-readability-*"

To remove all checks (usually to add a specific check):

dart ./tools/clang_tidy/bin/main.dart --checks="-*,<only-check-to-run>"

Specify a specific build

There are some rules that are only applicable to certain builds, or to check a difference in behavior between two builds.

Use --target-variant to specify a build:

dart ./tools/clang_tidy/bin/main.dart --target-variant <engine-variant>

For example, to check the android_debug_unopt build:

dart ./tools/clang_tidy/bin/main.dart --target-variant android_debug_unopt

In rarer cases, for example comparing two different checkouts of the engine, use --src-dir=<path/to/engine/src>.

Lint entire repository

When adding a new lint rule, or when checking lint rules that impact files that have not changed.

Use --lint-all to lint all files in the repo:

dart ./tools/clang_tidy/bin/main.dart --lint-all

Or, provide a regular expression to lint files that match:

dart ./tools/clang_tidy/bin/main.dart --lint-regex=".*test.*\.cc"

⚠️ WARNING: This may take a long time to run if a pattern is not provided or if the pattern matches a large number of files, i.e. on the order of thousands of files could take 30 minutes or more to run and lock your machine.

Footnotes

1. Modified files are determined by a git diff command compared to HEAD. ↩

2. Latest build is the last updated directory in src/out/. ↩