72 Annotation retention

CompileHint has source retention; CatalogHint has binary retention. Neither is returned by runtime annotation lookup. Binary metadata remains available to compiler and documentation tooling; runtime reflection requires RuntimeRetention.

import std.annotation.TypeTarget
import std.annotation.SourceRetention
import std.annotation.BinaryRetention

annotation CompileHint implements TypeTarget, SourceRetention {}
annotation CatalogHint implements TypeTarget, BinaryRetention {}

@CompileHint()
@CatalogHint()
class Task {}

main() {
  printLine(Task.class.annotation<CompileHint>() == null)
  printLine(Task.class.annotation<CatalogHint>() == null)
}

Expected output:

true
true

Try it: Change CatalogHint to RuntimeRetention and predict the second line.

Precise rules: Reference.