enum_constant_with_non_const_constructor

The invoked constructor isn't a 'const' constructor.

The analyzer produces this diagnostic when an enum value is being created using either a factory constructor or a generative constructor that isn't marked as being const.

The following code produces this diagnostic because the enum value e is being initialized by a factory constructor:

enum E {
  e();

  factory E() => e;
}

Use a generative constructor marked as const:

enum E {
  e._();

  factory E() => e;

  const E._();
}