mixin_inherits_from_not_object
The class '{0}' can't be used as a mixin because it extends a class other than 'Object'.
Description
#The analyzer produces this diagnostic when a class that extends a class other than Object
is used as a mixin.
Example
#The following code produces this diagnostic because the class B
, which extends A
, is being used as a mixin by C
:
//@dart=2.19
class A {}
class B extends A {}
class C with B {}
Common fixes
#If the class being used as a mixin can be changed to extend Object
, then change it:
//@dart=2.19
class A {}
class B {}
class C with B {}
If the class being used as a mixin can't be changed and the class that's using it extends Object
, then extend the class being used as a mixin:
class A {}
class B extends A {}
class C extends B {}
If the class doesn't extend Object
or if you want to be able to mix in the behavior from B
in other places, then create a real mixin:
class A {}
mixin M on A {}
class B extends A with M {}
class C extends A with M {}
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.