Loophole in "no inlined with opaque" checking

[odersky]

The following code is adapted from a contributors comment

object refined:
  opaque type Positive = Int

  object Positive extends PositiveFactory

  trait PositiveFactory:
    inline def apply(value: Int): Positive = f(value) // error expected here
    def f(x: Positive): Positive = x

@main def run: Unit =
  import refined.*
  val x = 9
  val nine = Positive.apply(x)

Behavior: At phase inlinining, the following error message;

-- [E007] Type Mismatch Error: opaque-inline.scala:14:28 -----------------------
14 |  val nine = Positive.apply(x)
   |                            ^
   |                            Found:    (x : Int)
   |                            Required: refined.Positive

longer explanation available when compiling with `-explain`

The error message makes no sense here. It came from the inlined expansion of f(value) which no longer typechecks
since the code is now outside of the region where the opaque alias was defined.

Expected Either an error on the definition of apply:

-- Error: opaque-inline.scala:8:15 ---------------------------------------------
8 |    inline def apply(value: Int): Positive = f(value)
  |               ^
  |Implementation restriction: No inline methods allowed where opaque type aliases are in scope

Or, if we can lift the implementation restriction, successful compilation with -Ycheck:all passing.