Linter for Dart #

The Dart Linter package defines lint rules that identify and report on "lints" found in Dart code. Linting is performed by the Dart analysis server and the dartanalyzer commandline tool.

Installing #

The linter is bundled with the Dart SDK; if you have an updated Dart SDK already, you're done!

Alternatively, if you want to contribute to the linter or examine the source, clone the linter repo like this:

$ git clone https://github.com/dart-lang/linter.git

Usage #

The linter gives you feedback to help you catch potential errors and keep your code in line with the published Dart Style Guide. Currently enforceable lint rules (or "lints") are catalogued here and can be configured via an analysis options file. The linter is run from within the dartanalyzer command-line tool shipped with the Dart SDK. Assuming you have lints configured in an analysis_options.yaml file with these contents:

linter:
  rules:
    - annotate_overrides
    - hash_and_equals
    - prefer_is_not_empty

you could lint your package like this:

$ dartanalyzer --options analysis_options.yaml .

and see any violations of the annotate_overrides, hash_and_equals, and prefer_is_not_empty rules in the console. To help you choose the rules you want to enable for your package, we have provided a complete list of rules. For the lints that are enforced internally at Google, see package:pedantic. For a set of rules corresponding to the Effective Dart guide, see package:effective_dart.

If a specific lint warning should be ignored, it can be flagged with a comment. For example,

   // ignore: avoid_as
   (pm as Person).firstName = 'Seth';

tells the dartanalyzer to ignore this instance of the avoid_as warning.

End-of-line comments are supported as well. The following communicates the same thing:

   (pm as Person).firstName = 'Seth'; // ignore: avoid_as

To ignore a rule for an entire file, use the ignore_for_file comment flag. For example,

// ignore_for_file: avoid_as

void main() {
  ...
  (pm as Person).firstName = 'Seth';
}

tells the dartanalyzer to ignore all occurences of the avoid_as warning in this file.

As lints are treated the same as errors and warnings by the analyzer, their severity can similarly be configured in an options file. For example, an analysis options file that specifies

linter:
  rules:
    - avoid_as
analyzer:
  errors:
    avoid_as: error

tells the analyzer to treat avoid_as lints as errors. For more on configuring analysis see the analysis option file docs.

Contributing #

Feedback is greatly appreciated and contributions are welcome! Please read the contribution guidelines; mechanics of writing lints are covered here.

Features and bugs #

Please file feature requests and bugs in the issue tracker.