native_field_not_static

Native fields must be static.

The analyzer produces this diagnostic when an instance field in a class has been annotated with @Native. Native fields refer to global variables in C, C++ or other native languages, whereas instance fields in Dart are specific to an instance of that class. Hence, native fields must be static.

For more information about FFI, see C interop using dart:ffi.

The following code produces this diagnostic because the field f in the class C is @Native, but not static:

import 'dart:ffi';
​
class C {
  @Native<Int>()
  external int f;
}

Either make the field static:

import 'dart:ffi';
​
class C {
  @Native<Int>()
  external static int f;
}

Or move it out of a class, in which case no explicit static modifier is required:

import 'dart:ffi';
​
class C {
}
​
@Native<Int>()
external int f;

If you meant to annotate an instance field that should be part of a struct, omit the @Native annotation:

import 'dart:ffi';
​
final class C extends Struct {
  @Int()
  external int f;
}