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Check Unused L10n

Checks unused members of classes that provide localization strings.

An example of such class:

class ClassWithLocalization {
String get title {
return Intl.message(
'Hello World',
name: 'title',
desc: 'Title for the Demo application',
locale: localeName,

Read more about this localization approach in the Flutter docs.


This command uses --class-pattern option to find classes that are used for accessing localization string. Passing it is mandatory.

To execute the command, run:

$ dcm check-unused-l10n lib # or dcm ul lib

Full command description:

Usage: dcm check-unused-l10n [arguments] <directories>
-h, --help Print this usage information.

-p, --class-pattern (mandatory) The pattern to detect classes providing localization.

-r, --reporter=<console> Analysis output format.
[console (default), json, codeclimate, gitlab, checkstyle]
-a, --absolute-path Show absolute paths in console reporter output.
--json-path=<path/to/file.json> Path to the JSON file with the analysis output.

-c, --print-config Print resolved config.

--root-folder=<./> Root folder.
(defaults to the current directory)
-s, --sdk-path=<directory-path> Dart SDK directory path.
If the project has a `.fvm/flutter_sdk` symlink, it will be used if the SDK is not found.
-e, --exclude=<{**/*.g.dart,**/*.freezed.dart}> File paths in Glob syntax to be exclude.
(defaults to "{**/*.g.dart,**/*.freezed.dart}")

--[no-]congratulate Don't show output even when there are no issues.

--verbose Show verbose logs.

--ci-key The license key to run on CI server. Can be provided via DCM_CI_KEY env variable.
--email The email used to purchase the license. Can be provided via DCM_EMAIL env variable.

--no-analytics Disable sending anonymous usage statistics.

--[no-]fatal-unused Treat find unused l10n as fatal.
(defaults to on)

Output example


Use --reporter=console to enable this format.



The reporter prints a single JSON object containing meta information and the unused file paths. Use --reporter=json to enable this format.

The root object fields are

  • formatVersion - an integer representing the format version (will be incremented each time the serialization format changes)
  • timestamp - a creation time of the report in YYYY-MM-DD HH:MM:SS format
  • unusedLocalizations - an array of unused files
"formatVersion": 2,
"timestamp": "2021-04-11 14:44:42",
"unusedLocalizations": [

The unusedLocalizations object fields are

  • path - a relative path of the unused file
  • className - a name of the class that has unused members
  • issues - an array of issues detected in the target class
"path": "lib/src/some/class.dart",
"className": "class",
"issues": [

The issue object fields are

  • memberName - unused class member name
  • offset - a zero-based offset of the class member location in the source
  • line - a zero-based line of the class member location in the source
  • column - a zero-based column of class member the location in the source
"memberName": "someGetter",
"offset": 156,
"line": 7,
"column": 1


Reports unused l10n issues in merge requests based on Code Quality custom tool. Use --reporter=gitlab to enable this format.


Use --reporter=checkstyle to enable this format.

<?xml version="1.0"?>
<checkstyle version="10.0">
<file name="example.dart">
<error line="5" column="3" severity="warning" message="Unused method someMethod()" source="unused-localization-issue"/>