Type alias affects inference of higher kinded type parameter

[ddtthh]

Compiler version

3.3.0, 3.3.1-RC1,2.13.11,2.12.18

Minimized code

trait Functor[F[_]] {
  def map[A, B](fa: F[A])(f: A => B): F[B]  
}

implicit class Extension[F[_]: Functor, A](target: F[A]) {
  def map[B](f: A => B): F[B] = implicitly[Functor[F]].map(target)(f)
}

implicit def instance[X]: Functor[Container] = new Functor[Container] {
  def map[A, B](fa: Container[A])(f: A => B) = Container(f(fa.value))
}


case class Container[A](value: A)

type G[A] = Container[List[A]]
def create: G[Int] = Container(List(5))

println((create: Container[List[Int]]).map(2 :: _)) // compiles
println(create.map(2 :: _)) // fails to compile

Output

value map is not a member of G[Int].
An extension method was tried, but could not be fully constructed:
Extension[[A] =>> Container[List[A]], Int](create)(instance[X])

Expectation

The type alias G[A] causes the type parameter F[_] of implicit class Extension to be inferred to [A] => Container[List[A]] which does not exhibit the required instance of Functor.

I would expect the compiler to expand G[Int] to Container[List[Int]] and then infer F[_] to Container[_], at least when the other candidate fails to type check. Not doing so requires annotating the expanded type to call extension methods.