implements_non_class

Classes and mixins can only implement other classes and mixins.

The analyzer produces this diagnostic when a name used in the implements clause of a class or mixin declaration is defined to be something other than a class or mixin.

The following code produces this diagnostic because x is a variable rather than a class or mixin:

var x;
class C implements x {}

If the name is the name of an existing class or mixin that's already being imported, then add a prefix to the import so that the local definition of the name doesn't shadow the imported name.

If the name is the name of an existing class or mixin that isn't being imported, then add an import, with a prefix, for the library in which it's declared.

Otherwise, either replace the name in the implements clause with the name of an existing class or mixin, or remove the name from the implements clause.

Unless stated otherwise, the documentation on this site reflects Dart 3.8.0. Page last updated on 2025-05-08. View source or report an issue.