Hi :wave: what use case does <this error> report o...

# compiler

[Jorge Castillo]

Hi 👋 what use case does this error report on? Seems to be related to annotated inline lambdas with annotations using non source retention (any annotations that survive until the output binaries), maybe related to closure capturing but not 100% sure.

[Jorge Castillo]

Looking twice seems logical that you can't annotate with retention != SOURCE since inline lambdas are effectively inlined into their caller's body at compile time, so they'll not be stored / retained anywhere and therefore there's nothing to annotate on the output binaries.

[Jorge Castillo]

Still I'm not able to reproduce this error with a minimal sample code. I'd expect this to fail following that reasoning:

@Retention(AnnotationRetention.BINARY)
@Target(
  AnnotationTarget.FUNCTION,
  AnnotationTarget.TYPE
)
annotation class SomeAnnotation

inline fun a(f: @SomeAnnotation (String) -> Int): Int = f("Hello world")

[Jorge Castillo]

Got it, needed to annotate on call site to trigger the error: i.e:

@Target(AnnotationTarget.FUNCTION)
annotation class FunAnn

inline fun myFun(a: Int, f: (Int) -> String): String = f(a)

fun main() {
  myFun(1) @FunAnn { it.toString() }
}