cast_nullable_to_non_nullable

Don't cast a nullable value to a non nullable type.

DON'T cast a nullable value to a non nullable type. This hides a null check and most of the time it is not what is expected.

BAD:

class A {}
class B extends A {}

A? a;
var v = a as B;
var v = a as A;

GOOD:

class A {}
class B extends A {}

A? a;
var v = a! as B;
var v = a!;

To enable the cast_nullable_to_non_nullable rule, add cast_nullable_to_non_nullable under linter > rules in your analysis_options.yaml file:

linter:
  rules:
    - cast_nullable_to_non_nullable

If you're instead using the YAML map syntax to configure linter rules, add cast_nullable_to_non_nullable: true under linter > rules:

linter:
  rules:
    cast_nullable_to_non_nullable: true

Unless stated otherwise, the documentation on this site reflects Dart 3.6.2. Page last updated on 2025-01-27. View source or report an issue.