mismatched_annotation_on_struct_field

The annotation doesn't match the declared type of the field.

The analyzer produces this diagnostic when the annotation on a field in a subclass of Struct or Union doesn't match the Dart type of the field.

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

The following code produces this diagnostic because the annotation Double doesn't match the Dart type int:

import 'dart:ffi';

final class C extends Struct {
  @Double()
  external int x;
}

If the type of the field is correct, then change the annotation to match:

import 'dart:ffi';

final class C extends Struct {
  @Int32()
  external int x;
}

If the annotation is correct, then change the type of the field to match:

import 'dart:ffi';

final class C extends Struct {
  @Double()
  external double x;
}

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.