Removing use of dart:mirrors to allow AOT compile

[davidmorgan]

The latest source_gen release deprecates TypeChecker.fromRuntime, because it uses mirrors

https://pub.dev/documentation/source_gen/3.1.0/source_gen/TypeChecker/TypeChecker.fromRuntime.html

the intended replacement is the new TypeChecker.typeNamed

https://pub.dev/documentation/source_gen/3.1.0/source_gen/TypeChecker/TypeChecker.typeNamed.html

--the is a little looser than TypeChecker.fromRuntime, it gets the name from the type you pass and then you should also explicitly pass a package name, so it matches name+package instead of full name+URI. This is usually what you want! As it doesn't make sense to stop detecting an annotation because it moved between files in the same package.

The next source_gen major version bump will remove TypeChecker.typeNamed, and then it will be possible to compile AOT. I need to teach build_runner to compile AOT in the meantime, work in progress :)

One important note, the source_gen GeneratedForAnnotation uses TypeChecker.fromRuntime, you can keep using the annotation generator but you should start passing the annotation package name now, it will switch to TypeChecker.typeNamed with the breaking release.

https://pub.dev/documentation/source_gen/3.1.0/source_gen/GeneratorForAnnotation/GeneratorForAnnotation.html