Intellij has wrong scala syntax errors

Question

I have this piece of code:

object Application {
  def main(args: Array[String]) {
    import scala.concurrent.ExecutionContext.Implicits.global

    val ws = new NingWSClient(new AsyncHttpClientConfig.Builder().build())
    ws.url("https://www.google.com").get() onSuccess {
      case resp: WSResponse => {
        println("Hello");
      }
      case _ => {
        println("Error");
      }
    }
  }
}

Every dependency is well defined inside the build.sbt like so:

name := "example"

version := "1.0"

scalaVersion := "2.11.4"

libraryDependencies ++= Seq(
  "com.typesafe.play" %% "play-ws" % "2.4.0-M2",
  "com.typesafe.play" %% "play-json" % "2.4.0-M2"
)

But Intellij looks like this when viewing my project:

Could somebody tell me what I'm doing wrong because I'm clueless and this is really annoying because my imports are constantly being removed by Intellij.

Answer 1

This looks like an IntelliJ (or Scala plugin) bug. Sometimes scala namespace does not seem to be handled well - I have seen it with my projects as well since I gave upgraded to version 14. Sometimes it helps to use File / Invalidate Caches/Restart.

Sometimes even adding / removing Scala SDK and invalidating caches does not help. In such case installing scalap.jar from issue SCL-8025 Standard scala library unrecognized on sbt project creation on 2.11.4 might help (the scala plugin location was %userprofile%\.IntelliJIdea14\config\plugins\Scala\lib on my computer).

Another issue SCL-7900 Scala import/auto-complete problem seems to suggest the problem shows when Idea uses JRE from Java 8 - uninstalling 1.8 JDK or setting a IDEA_JDK_64 variable to point to jdk7-64bit files is also supposed to fix the issue.