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Check Unused Code

Checks unused classes, functions, top level variables, extensions, enums, mixins and type aliases.


This implementation doesn't check for particular class members (fields / properties / methods) usage. If you need this functionality, refer to check-unused-code command for Teams version.

To execute the command, run:

$ flutter pub run dart_code_metrics:metrics check-unused-code lib

Full command description:

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

-r, --reporter=<console> The format of the output of the analysis.
[console (default), json]
--report-to-file=<path/to/report.json> The path, where a JSON file with the analysis result will be placed (only for the JSON reporter).

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

--root-folder=<./> Root folder.
(defaults to current directory)
--sdk-path=<directory-path> Dart SDK directory path.
Should be provided only when you run the application as compiled executable( and automatic Dart SDK path detection fails.
--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.

--[no-]monorepo Treat all exported code as unused by default.

--[no-]fatal-unused Treat find unused file as fatal.

Suppressing the command

In order to suppress the command add the ignore: unused-code comment. To suppress for an entire file add ignore_for_file: unused-code to the beginning of a file.

Monorepo support

By default the command treats all code that is exported from the package as used. To disable this behavior use --monorepo flag. This might be useful when all the packages in your repository are only used within the repository and are not published to the pub.

Output example


Use --reporter=console to enable this format.



The reporter prints a single JSON object containing meta information and the unused code 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
  • unusedCode - an array of unused code issues
"formatVersion": 2,
"timestamp": "2021-04-11 14:44:42",
"unusedCode": [

The unusedCode object fields are

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

The issue object fields are

  • declarationType - unused declaration type
  • declarationName - unused declaration 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
"declarationType": "extension",
"declarationName": "StringX",
"offset": 156,
"line": 7,
"column": 1