const_constructor_with_field_initialized_by_non_const

Can't define the 'const' constructor because the field '{0}' is initialized with a non-constant value.

The analyzer produces this diagnostic when a constructor has the keyword const, but a field in the class is initialized to a non-constant value.

The following code produces this diagnostic because the field s is initialized to a non-constant value:

String x = '3';
class C {
  final String s = x;
  const C();
}

If the field can be initialized to a constant value, then change the initializer to a constant expression:

class C {
  final String s = '3';
  const C();
}

If the field can't be initialized to a constant value, then remove the keyword const from the constructor:

String x = '3';
class C {
  final String s = x;
  C();
}

Unless stated otherwise, the documentation on this site reflects Dart 3.8.1. Page last updated on 2025-05-08. View source or report an issue.