A redirecting constructor can't redirect to a type alias that expands to a type parameterDRT-W1594

The analyzer produces this diagnostic when a redirecting factory constructor redirects to a type alias, and the type alias expands to one of the type parameters of the type alias. This isn't allowed because the value of the type parameter is a type rather than a class.

Example

The following code produces this diagnostic because the redirect to B<A> is to a type alias whose value is T, even though it looks like the value should be A:

class A implements C {}

typedef B<T> = T;

abstract class C {
  factory C() = B<A>;
}

Common fixes

Use either a class name or a type alias that is defined to be a class rather than a type alias defined to be a type parameter:

class A implements C {}

abstract class C {
  factory C() = A;
}