When using the Spray API, I often encounter compiler errors reported by Scala IDE which compile correctly in SBT. For example, in Spray there is an Unmarshaller type and also a Unmarshaller object. This seems to have something to do with the problem. For this code:

import spray.http._
import spray.httpx.marshalling._
import spray.httpx.unmarshalling._

object Unmarshallers {

  val `application/special-custom-thing` = MediaTypes.register(MediaType.custom("application/special-custom-thing"))

  case class SpecialCustomThing(value: String)

  val SPARQLQueryBodyUnmarshaller = Unmarshaller.delegate[String, SpecialCustomThing](`application/special-custom-thing`)(SpecialCustomThing)

}

The IDE says "value delegate is not a member of object spray.httpx.unmarshalling.Unmarshaller". I have attached an SBT project and also a screenshot of the IDE showing the error. Here are the installation details from the IDE plugin:

Scala IDE version:
4.0.0.rc1-2_11-201410211318-7115fbd
Scala compiler version:
2.11.2.
Scala library version:
2.11.2.
Eclipse version:
4.3.2.v20140221-1700
Class loader store: 2 entries
Compiler v. 2.11.2.(/Applications/Eclipse/plugins/org.scala-lang.scala-compiler_2.11.2.v20140721-095018-73fb460c1c.jar)
Compiler v. 2.10.4.(/Applications/Eclipse/plugins/org.scala-ide.scala210.jars_4.0.0.201410211316/target/jars/scala-compiler.jar)

The project is set to use Scala 2.10.4.