undefined_referenced_parameter

The parameter '{0}' isn't defined by '{1}'.

The analyzer produces this diagnostic when an annotation of the form UseResult.unless(parameterDefined: parameterName) specifies a parameter name that isn't defined by the annotated function.

The following code produces this diagnostic because the function f doesn't have a parameter named b:

import 'package:meta/meta.dart';

@UseResult.unless(parameterDefined: 'b')
int f([int? a]) => a ?? 0;

Change the argument named parameterDefined to match the name of one of the parameters to the function:

import 'package:meta/meta.dart';

@UseResult.unless(parameterDefined: 'a')
int f([int? a]) => a ?? 0;

Unless stated otherwise, the documentation on this site reflects Dart 3.7.3. Page last updated on 2025-05-08. View source or report an issue.