为什么scala编译器在重载并且具有泛型类型参数时无法找到隐式参数值/转换？

Question

Scala 2.8.1

Take the following class hierarchy

abstract class A

class B extends A

class C extends A

Why is the scala compiler unable to find the implicit parameter for send when sending an instance of B below

implicit def routingKeyFor[T <: A](value: T) =
  value.getClass.getSimpleName

implicit def routingKeyFor(value: C) = "custom C"

def send[T <: A](value: T)(implicit createRoutingKey: T => String):
Validation[Throwable, String] = Success(createRoutingKey(value))

val resultOfSendingB = send(new B)
val resultOfSendingC = send(new C)

Why is the compiler able to locate the value for the implicit parameter when the generic version of routingKeyFor is renamed?

implicit def someOtherName[T <: A](value: T) = 
  value.getClass.getSimpleName

Answer 1

The second implicit is shadowing the first one. Why is anyone's guess, and you might open an issue for it (after verifying that this wasn't reported before), but it might just be one of those things that throw a spanner into the works of type inference.