Missing concrete implementation of super-invoked memberDRT-W1486

The analyzer produces this diagnostic when a mixin application contains an invocation of a member from its superclass, and there's no concrete member of that name in the mixin application's superclass.

Example

The following code produces this diagnostic because the mixin M contains the invocation super.m(), and the class A, which is the superclass of the mixin application A+M, doesn't define a concrete implementation of m:

abstract class A {
  void m();
}

mixin M on A {
  void bar() {
    super.m();
  }
}

abstract class B extends A with M {}

Common fixes

If you intended to apply the mixin M to a different class, one that has a concrete implementation of m, then change the superclass of B to that class:

abstract class A {
  void m();
}

mixin M on A {
  void bar() {
    super.m();
  }
}

class C implements A {
  void m() {}
}

abstract class B extends C with M {}

If you need to make B a subclass of A, then add a concrete implementation of m in A:

abstract class A {
  void m() {}
}

mixin M on A {
  void bar() {
    super.m();
  }
}

abstract class B extends A with M {}