type_init_formals

Don't needlessly type annotate initializing formals.

The analyzer produces this diagnostic when an initializing formal parameter (this.x) or a super parameter (super.x) has an explicit type annotation that is the same as the field or overridden parameter.

If a constructor parameter is using this.x to initialize a field, then the type of the parameter is implicitly the same type as the field. If a constructor parameter is using super.x to forward to a super constructor, then the type of the parameter is implicitly the same as the super constructor parameter.

The following code produces this diagnostic because the parameter this.c has an explicit type that is the same as the field c:

class C {
  int c;

  C(int this.c);
}

The following code produces this diagnostic because the parameter super.a has an explicit type that is the same as the parameter a from the superclass:

class A {
  A(int a);
}

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

Remove the type annotation from the parameter:

class C {
  int c;

  C(this.c);
}

Unless stated otherwise, the documentation on this site reflects Dart 3.8.0. Page last updated on 2025-05-08. View source or report an issue.