Class annotation values with $ in name are null when used in Kotlin source

[bcorso]

This issue was brought up in Dagger (google/dagger#4197), but looks like the underlying cause is a bug in KSP.

Say we have the following classes:

class `SomeClass$WithDollarSign`

annotation class MyAnnotation(val classes: Array<KClass<*>>)

@MyAnnotation(classes = [String::class, `SomeClass$WithDollarSign`::class, Number::class])
class Foo

The issue is that if we use KSP to inspect the annotation values of MyAnnotation.classes then the SomeClass$WithDollarSign type is returned as null. For example, say we have the following KSP processor:

class MyProcessor(
  private val codeGenerator: CodeGenerator,
  private val logger: KSPLogger,
  private val options: Map<String, String>
) : SymbolProcessor {

  @OptIn(KspExperimental::class)
  override fun process(resolver: Resolver): List<KSAnnotated> {
    val fooName = resolver.getKSNameFromString("Foo")
    val fooClass = resolver.getClassDeclarationByName(fooName)
    fooClass?.annotations?.forEach { annotation ->
      println("${annotation.annotationType}: ${
          annotation.arguments.map { "${it.name?.asString()}: ${it.value}" }.toList() 
      }")
    }
    return listOf()
  }
}

This will print the following:

MyAnnotation: [classes: [String, null, Number]]

Note: The above issue only happens when the annotation is used in a kotlin source. If the annotation is used in java source then things work as expected and I get:

MyAnnotation: [classes: [String, SomeClass$WithDollarSign, Number]]

[bcorso]

Edit:

I mentioned above that the issue didn't happen when the annotation is used in a java source, but I realize now that that's only if the source is defined in the current compilation unit. If the Java source is defined in a dependency of the current compilation unit then the same issue of getting a null annotation value type happens for both Java and Kotlin sources.