implicit paramater search

// implicit parameter の探索
class SM[T]
object SM { implicit object MA2 extends M[A2] }
class M[T] extends SM[T]
object M { implicit object MA extends M[A] }

class A
class A2
class B
object B {
  implicit object MB extends M[B]
  implicit object MB2 extends M[B2]
}
class B2 extends B
class C

class F {
  def f[T: M](t: T) = "ok"
}
object F { implicit object MC extends M[C] }

val f = new F
f.f(new A)
f.f(new A2)
f.f(new B)
f.f(new B2)
f.f(new C)	// error


/////////////////////////////////
object D {
  class E[T]
  object E { implicit object EB extends E[B] }
  implicit object EC extends E[C]
}
def df[T: D.E](t: T) = "ok"

df(new A)	// error
df(new B)
df(new C)	// なぜかこちらでも通る