non_constant_annotation_constructor

Annotation creation can only call a const constructor.

The analyzer produces this diagnostic when an annotation is the invocation of an existing constructor even though the invoked constructor isn't a const constructor.

The following code produces this diagnostic because the constructor for C isn't a const constructor:

@C()
void f() {
}

class C {
  C();
}

If it's valid for the class to have a const constructor, then create a const constructor that can be used for the annotation:

@C()
void f() {
}

class C {
  const C();
}

If it isn't valid for the class to have a const constructor, then either remove the annotation or use a different class for the annotation.

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.