Compiler fails to inline

[allanrenucci]

Code snippet minimised from collection strawman:

trait Iterable[A] {
  def concat[B >: A](that: Iterable[B]): Iterable[B] = ???
  @`inline` final def ++ [B >: A](that: Iterable[B]): Iterable[B] = concat(that)
}

class BitSet extends Iterable[Int] {
  def concat(that: Iterable[Int]): BitSet = ???
  @`inline` final def ++ (that: Iterable[Int]): BitSet = concat(that)
}

class Test {
  def test(x: BitSet, y: Iterable[Int]): Unit = {
    val foo = x ++ y
  }
}

-- Error: tests/allan/Test.scala:68:16 -----------------------------------------
68 |    val foo = x ++ y
   |              ^^^^^^
   |    overloaded alternatives of method concat in class BitSet with types
   |     (that: Iterable[Int]): BitSet
   |     [B >: Int](that: Iterable[B]): Iterable[B] does not take parameters
   | This location is in code that was inlined at tests/allan/Test.scala:68

scalac can compile. Dotty can compile without the inline annotations.