extra_ annotation_ on_ struct_ field
Fields in a struct class must have exactly one annotation indicating the native type.
Description
#
The analyzer produces this diagnostic when a field in a subclass of
Struct
has more than one annotation describing the native type of the
field.
For more information about FFI, see C interop using dart:ffi.
Example
#
The following code produces this diagnostic because the field
x
has two
annotations describing the native type of the field:
import 'dart:ffi';
final class C extends Struct {
@Int32()
@Int16()
external int x;
}
Common fixes
#Remove all but one of the annotations:
import 'dart:ffi';
final class C extends Struct {
@Int32()
external int x;
}
Unless stated otherwise, the documentation on this site reflects Dart 3.9.2. Page last updated on 2025-9-4. View source or report an issue.