ffi_native_unexpected_number_of_parameters_with_receiver

Unexpected number of Native annotation parameters. Expected {0} but has {1}. Native instance method annotation must have receiver as first argument.

The analyzer produces this diagnostic when the type argument used on the @Native annotation of a native method doesn't include a type for the receiver of the method.

The following code produces this diagnostic because the type argument on the @Native annotation (Void Function(Double)) doesn't include a type for the receiver of the method:

import 'dart:ffi';

class C {
  @Native<Void Function(Double)>()
  external void f(double x);
}

Add an initial parameter whose type is the same as the class in which the native method is being declared:

import 'dart:ffi';

class C {
  @Native<Void Function(C, Double)>()
  external void f(double x);
}

Unless stated otherwise, the documentation on this site reflects Dart 3.7.3. Page last updated on 2025-05-08. View source or report an issue.