Resolution / inference in ElementAnnotationImpl.annotationAst is incomplete

[scheglov]

The following test, when added to ClassResolutionMixin, passes with task model, and fails with AnalysisDriver.

  Expected: 'List<num>'
    Actual: 'null'

The failure disappears if I move class C {} with its annotation into the test file.

That's because we clone the annotation and store into the element model.

Which does not help to clients that use just element model and look at annotations from other files, possibly resynthesized from summaries.

  solo_test_XXX() async {
    newFile('/test/lib/a.dart', content: r'''
class A {
  final x;
  const A(this.x);
}

@A([1, 2.3])
class C {}
''');
    addTestFile(r'''
import 'a.dart';

C c;
''');
    await resolveTestFile();
    assertNoTestErrors();

    ClassElement c = findNode.simple('C c').staticElement;
    ElementAnnotationImpl m = c.metadata[0];
    var listType = m.annotationAst.arguments.arguments[0].staticType;
    assertElementTypeString(listType, 'List<num>');
  }

[scheglov]

Oh, and this is only a symptom of problems that we have for constants in general.
This test also fails with AnalysisDriver (or should I say with summaries instead?).
This is the same problem as outlined in https://dart-review.googlesource.com/c/sdk/+/80761, tracked as #33441

  solo_test_XXX() async {
    newFile('/test/lib/a.dart', content: r'''
const Object x = [1];
''');
    addTestFile(r'''
import 'a.dart';

const List<String> y = x;
''');
    await resolveTestFile();
    assertHasTestErrors();
  }

[srawlins]

Not sure if we can act on this bug. I don't see ClassResolutionMixin any longer, and I don't see specifics about either test case that are the (maybe hypothesized) problem.