Members from refinements cannot be exported

[prolativ]

Compiler version

3.3.2-RC1-bin-20230718-da16f43-NIGHTLY and before

Minimized code

class Sel extends Selectable:
  def selectDynamic(name: String) = ???

val sel = (new Sel).asInstanceOf[Sel {def xxx: String}]
val a: String = sel.xxx
val b: String =
  import sel.xxx
  xxx
val c: String =
  object Tmp:
    export sel.xxx
  Tmp.xxx

Output

[error] SelectableExport.scala:11:16
[error] no eligible member xxx at sel
[error] sel.xxx cannot be exported because it is not accessible
[error]     export sel.xxx
[error]                ^^^
[error] /var/folders/rp/f9y80jvs54lcy26rxnt2y2kw0000gn/T/SelectableExport.scala:12:3
[error] value xxx is not a member of object Tmp
[error]   Tmp.xxx
[error]   ^^^^^^^

Expectation

The code snippet should compile. All of a, b and c should have the same runtime value (given that selectDynamic gets an actual implementation). Similarly this should work for methods in refinements that require an argument and desugar to a call to applyDynamic.

[prolativ]

@odersky should this work in theory or is it a known limitation which cannot be fixed with the current design of structural types?

[bishabosha]

I think the spec is pretty clear, exports only export members, and structural refinements are not members. However implementation wise we do fully type the prefix, so structural refinements could be considered - however they can never be stable

[odersky]

Good analysis. Yes, we only export members. Structural refinements are not considered, and it would be very hard to add them.