packed_ annotation_ alignment
Only packing to 1, 2, 4, 8, and 16 bytes is supported.
Description
#
The analyzer produces this diagnostic when the argument to the
Packed
annotation isn't one of the allowed values: 1, 2, 4, 8, or 16.
For more information about FFI, see C interop using dart:ffi.
Example
#
The following code produces this diagnostic because the argument to the
Packed
annotation (3
) isn't one of the allowed values:
import 'dart:ffi';
@Packed(3)
final class C extends Struct {
external Pointer<Uint8> notEmpty;
}
Common fixes
#Change the alignment to be one of the allowed values:
import 'dart:ffi';
@Packed(4)
final class C extends Struct {
external Pointer<Uint8> notEmpty;
}
Unless stated otherwise, the documentation on this site reflects Dart 3.9.2. Page last updated on 2025-9-1. View source or report an issue.