Yeah, I did try macros when they were in development. Now that macros are cancelled, I’m experimenting with augmentations only. However, I’m unable to get them running on the dev channel. I also had to enable the macros experimental flag; otherwise, I get lint errors.

Dart version:

$ dartdev --version
Dart SDK version: 3.12.0-154.0.dev (dev) (Mon Feb 16 12:09:02 2026 -0800) on "macos_arm64"

analysis_options.yaml:

include: package:lints/recommended.yaml

analyzer:
  enable-experiment:
    - augmentations
    - macros

main.dart:

void main() {
  print(A().x);
}

class A {}

augment class A {
  int x = 1;
}

Command used:

$ dartdev run --enable-experiment=augmentations,macros lib/main.dart

lib/main.dart:7:1: Error: Variables must be declared using the keywords 'const', 'final', 'var' or a type name.
Try adding the name of the type of the variable or the keyword 'var'.
augment class A {
^^^^^^^
lib/main.dart:7:1: Error: Expected ';' after this.
augment class A {
^^^^^^^
lib/main.dart:7:15: Error: 'A' is already declared in this scope.
augment class A {
              ^
lib/main.dart:5:7: Context: Previous declaration of 'A'.
class A {}
      ^

Did I miss anything? Please let me know if there’s any additional setup or flag required.

Augmentations #4154

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