initializing_formal_for_non_existent_field

'{0}' isn't a field in the enclosing class.

The analyzer produces this diagnostic when an initializing formal parameter is found in a constructor in a class that doesn't declare the field being initialized. Constructors can't initialize fields that aren't declared and fields that are inherited from superclasses.

The following code produces this diagnostic because the field x isn't defined:

class C {
  int? y;

  C(this.x);
}

If the field name was wrong, then change it to the name of an existing field:

class C {
  int? y;

  C(this.y);
}

If the field name is correct but hasn't yet been defined, then declare the field:

class C {
  int? x;
  int? y;

  C(this.x);
}

If the parameter is needed but shouldn't initialize a field, then convert it to a normal parameter and use it:

class C {
  int y;

  C(int x) : y = x * 2;
}

If the parameter isn't needed, then remove it:

class C {
  int? y;

  C();
}

Unless stated otherwise, the documentation on this site reflects Dart 3.8.1. Page last updated on 2025-05-08. View source or report an issue.