variable_length_array_not_last

Variable length 'Array's must only occur as the last field of Structs.

The analyzer produces this diagnostic when a variable length inline Array is not the last member of a Struct.

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

The following code produces this diagnostic because the field a0 has a type with three nested arrays, but only two dimensions are given in the Array annotation:

import 'dart:ffi';

final class C extends Struct {
  @Array.variable()
  external Array<Uint8> a0;

  @Uint8()
  external int a1;
}

Move the variable length inline Array to be the last field in the struct.

import 'dart:ffi';

final class C extends Struct {
  @Uint8()
  external int a1;

  @Array.variable()
  external Array<Uint8> a0;
}

If the inline array has a fixed size, annotate it with the size:

import 'dart:ffi';

final class C extends Struct {
  @Array(10)
  external Array<Uint8> a0;

  @Uint8()
  external int a1;
}

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.