Certain value classes compiled with Scala 2 can't be used with Scala 3

[jadenPete]

Compiler version

2.13.16 and 3.6.3

Minimized code

1. Compile the following code with Scala 2:

trait Tag

class Tagger[T](val value: T) extends AnyVal {
  def withTag: T & Tag = ???
}

2. Compile the following code with Scala 3:

object Main {
  def main(arguments: Array[String]): Unit = {
    val x = 2

    println(new Tagger(x).withTag)
  }
}

Output

Run the Scala 3 code and observe the following exception:

Exception in thread "main" java.lang.NoSuchMethodError: 'Tag Tagger$.withTag$extension(java.lang.Object)'
	at Main$.main(Scala3.scala:5)
	at Main.main(Scala3.scala)

Expectation

That NoSuchMethodError wouldn't be thrown.

[som-snytt]

Likely
#22177
#22525

I forgot my comment about a missing bridge; or is it just how the result is erased?

[jadenPete]

I forgot my comment about a missing bridge; or is it just how the result is erased?

Sorry, what do you mean by this?

[som-snytt]

I was thinking a bridge method is missing, but it's also possible the erasure of a type is different so that a method signature has changed. I haven't followed up to look at it, however.

[jadenPete]

Ah, ok. I'll keep an eye on those issues and see if this is still an issue once they've been closed. Thanks!