Skip to main content

mixin_super_class_constraint_non_interface

Only classes and mixins can be used as superclass constraints.

Description

#

The analyzer produces this diagnostic when a type following the on keyword in a mixin declaration is neither a class nor a mixin.

Example

#

The following code produces this diagnostic because F is neither a class nor a mixin:

dart
typedef F = void Function();

mixin M on F {}

Common fixes

#

If the type was intended to be a class but was mistyped, then replace the name.

Otherwise, remove the type from the on clause.