extension_type_constructor_with_super_invocation

Extension type constructors can't include super initializers.

The analyzer produces this diagnostic when a constructor in an extension type includes an invocation of a super constructor in the initializer list. Because extension types don't have a superclass, there's no constructor to invoke.

The following code produces this diagnostic because the constructor E.n invokes a super constructor in its initializer list:

extension type E(int i) {
  E.n() : i = 0, super.n();
}

Remove the invocation of the super constructor:

extension type E(int i) {
  E.n() : i = 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.