Illegal concrete member in EnumDRT-W1381

The analyzer produces this diagnostic when either an enum declaration, a class that implements Enum, or a mixin with a superclass constraint of Enum, declares or inherits a concrete instance member named either index, hashCode, or ==.

Examples

The following code produces this diagnostic because the enum E declares an instance getter named index:

enum E {
  v;

  int get index => 0;
}

The following code produces this diagnostic because the class C, which implements Enum, declares an instance field named hashCode:

abstract class C implements Enum {
  int hashCode = 0;
}

The following code produces this diagnostic because the class C, which indirectly implements Enum through the class A, declares an instance getter named hashCode:

abstract class A implements Enum {}

abstract class C implements A {
  int get hashCode => 0;
}

The following code produces this diagnostic because the mixin M, which has Enum in the on clause, declares an explicit operator named ==:

mixin M on Enum {
  bool operator ==(Object? other) => false;
}

Common fixes

Rename the conflicting member:

enum E {
  v;

  int get getIndex => 0;
}