Generative enum constructors can only be used as targets of redirectionDRT-W1435

The analyzer produces this diagnostic when a generative constructor defined on an enum is used anywhere other than to create one of the enum constants or as the target of a redirection from another constructor in the same enum.

Example

The following code produces this diagnostic because the constructor for E is being used to create an instance in the function f:

enum E {
  a(0);

  const E(int x);
}

E f() => const E(2);

Common fixes

If there's an enum constant with the same value, or if you add such a constant, then reference the constant directly:

enum E {
  a(0), b(2);

  const E(int x);
}

E f() => E.b;

If you need to use a constructor invocation, then use a factory constructor:

enum E {
  a(0);

  const E(int x);

  factory E.c(int x) => a;
}

E f() => E.c(2);