[cfe/macros]: empty metadata iterable at compile time

[helightdev]

Trying to resolve method metadata at definion class definition phase returns an empty metadata iterable at compile time but doesn't throw an exception, while the analyzer correctly generated the augmentation and correctly passes the full metadata list to the macro.

@TestMacro()
class TestClass {

  @TestAnnotation("Value!")
  void testMethod() {}

}

This example class generates following augmentation code using the analyzer

augment class TestClass {
external static prefix0.List<prefix1.GeneratedObject> get objects;
  augment static prefix0.List<prefix1.GeneratedObject> get objects => [prefix1.GeneratedObject([],0),prefix1.GeneratedObject([prefix2.TestAnnotation("Value!",),],1)];
}

but retrieving the getter generated by this at runtime results in following output:

void main(List<String> arguments) {
 for (var obj in TestClass.objects) {
   print(obj.count);
   print(obj.annotations);
 }
}

/usr/lib/dart/bin/dart --enable-experiment=macros --no-serve-devtools bin/cfe_metadata_reconstruction.dart
0
[]
0
[]

I took a while to even notice this behaviour since the analyzer output looks correct and the compiler doesn't throw an (Unimplemented-)Exception. Only noticed it once my stuff which actually needed the metadata entries broke.

The code of the macro is available at https://github.com/helightdev/cfe_metadata_reconstruction

The bug has been tested on a build of the current main branch

Dart SDK version: 3.5.0-edge.5a49a95b399cbed956d808bdfe594e1a3f2c9382 (main) (Tue Jun 11 12:36:05 2024 +0000) on "linux_x64"

[davidmorgan]

That's because we don't have a design that works for the CFE yet :) ... please follow dart-lang/language#3847 for progress on this one. Thanks!