Signature is different if method compiled by Scala 2

[bishabosha]

Compiler version

3.0.0-RC2

Minimized code

// reflection.scala (scala-reflect shim), compiled with Scala 2.13.5
package reflectshims

abstract class Universe {
  type Tree >: Null <: AnyRef with TreeApi
  trait TreeApi extends Product { this: Tree => }
}

trait Context {

  type Tree = universe.Tree

  val universe: Universe

}

// Scala2Macros.scala
package example

object Scala2Macro {
  def fooImpl(c: reflectshims.Context)(code: c.Tree): c.Tree = code
}

class Scala2Bundle(val c: reflectshims.Context) {
  def fooImpl(code: c.Tree): c.Tree = code
}

// MacroDefs.scala, compile with 3.0.0-RC2
package example

object MacroDefs {
  // here we simulate code generated for Scala 2 macro implementations

  def foo(code: String): String = Scala2Macro.fooImpl(??? : reflectshims.Context)(???).asInstanceOf[String]

  def foo2(code: String): String = {
    val bundle = new Scala2Bundle(null)
    bundle.fooImpl(???).asInstanceOf[String]
  }

}

Output

• compile Scala2Macros.scala with 2.13.5
• compile MacroDefs.scala
• the signature in TASTy for calling Scala2Macro.fooImpl is

fooImpl[Signed Signature(List(reflectshims.Context, reflectshims.Universe.TreeApi),reflectshims.Universe.TreeApi) @fooImpl]

• compile Scala2Macros.scala with 3.0.0-RC2
• compile MacroDefs.scala
• the signature in TASTy for calling Scala2Macro.fooImpl is

fooImpl[Signed Signature(List(reflectshims.Context, java.lang.Object),java.lang.Object) @fooImpl]

Expectation

I expect the signature to be the same

[bishabosha]

I am not so sure yet what is the cause of this thing, if it is an expected change specifically for Scala 3 compiled methods I would like to try and replicate the new erasure rules in Scala 2, e.g. probably related to #11603, #11808

[bishabosha]

In fact now I have seen that the bytecode signatures also change when compiled by Scala 2.13.5 vs Scala 3.0.0-RC2 this seems expected