inconsistent_inheritance

Superinterfaces don't have a valid override for '{0}': {1}.

The analyzer produces this diagnostic when a class inherits two or more conflicting signatures for a member and doesn't provide an implementation that satisfies all the inherited signatures.

The following code produces this diagnostic because C is inheriting the declaration of m from A, and that implementation isn't consistent with the signature of m that's inherited from B:

class A {
  void m({int? a}) {}
}

class B {
  void m({int? b}) {}
}

class C extends A implements B {
}

Add an implementation of the method that satisfies all the inherited signatures:

class A {
  void m({int? a}) {}
}

class B {
  void m({int? b}) {}
}

class C extends A implements B {
  void m({int? a, int? b}) {}
}

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