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wrong_number_of_type_arguments_constructor

Contents

The constructor '{0}.{1}' doesn't have type parameters.

The constructor '{0}.{1}` doesn't have type parameters.

Description

#

The analyzer produces this diagnostic when type arguments are provided after the name of a named constructor. Constructors can't declare type parameters, so invocations can only provide the type arguments associated with the class, and those type arguments are required to follow the name of the class rather than the name of the constructor.

Example

#

The following code produces this diagnostic because the type parameters (<String>) follow the name of the constructor rather than the name of the class:

dart
class C<T> {
  C.named();
}
C f() => C.named<String>();

Common fixes

#

If the type arguments are for the class' type parameters, then move the type arguments to follow the class name:

dart
class C<T> {
  C.named();
}
C f() => C<String>.named();

If the type arguments aren't for the class' type parameters, then remove them:

dart
class C<T> {
  C.named();
}
C f() => C.named();

Unless stated otherwise, the documentation on this site reflects Dart 3.8.0. Page last updated on 2025-05-19. View source or report an issue.