Mismatched parameter type in super constructorDRT-W1630

The analyzer produces this diagnostic when the type of a super parameter isn't a subtype of the corresponding parameter from the super constructor.

Example

The following code produces this diagnostic because the type of the super parameter x in the constructor for B isn't a subtype of the parameter x in the constructor for A:

class A {
  A(num x);
}

class B extends A {
  B(String super.x);
}

Common fixes

If the type of the super parameter can be the same as the parameter from the super constructor, then remove the type annotation from the super parameter (if the type is implicit, it is inferred from the type in the super constructor):

class A {
  A(num x);
}

class B extends A {
  B(super.x);
}

If the type of the super parameter can be a subtype of the corresponding parameter's type, then change the type of the super parameter:

class A {
  A(num x);
}

class B extends A {
  B(int super.x);
}

If the type of the super parameter can't be changed, then use a normal parameter instead of a super parameter:

class A {
  A(num x);
}

class B extends A {
  B(String x) : super(x.length);
}