field_must_be_external_in_struct
Fields of 'Struct' and 'Union' subclasses must be marked external.
Description
#The analyzer produces this diagnostic when a field in a subclass of either Struct
or Union
isn't marked as being external
.
For more information about FFI, see C interop using dart:ffi.
Example
#The following code produces this diagnostic because the field a
isn't marked as being external
:
dart
import 'dart:ffi';
final class C extends Struct {
@Int16()
int a;
}
Common fixes
#Add the required external
modifier:
dart
import 'dart:ffi';
final class C extends Struct {
@Int16()
external int a;
}
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.