A doozy of a compiler crash we saw at Egraphs

scala_compiler_crasher.scala

// This example produces a compiler error in Scala 2.9.1 and 2.9.2. It works fine in Scala 2.10M7.
// The error text is:  "java.lang.Error: symbol value blobKey does not exist in Crasher$$anonfun$1.apply"

object Crasher {
  def main(args: Array[String]) {
    println("This will never be printed because the compiler will crash")
  }
}

class Crasher { // this can be a trait, class, object, whatever
  
  def filter = new Filter // has to be a def

  // have to use the default args for first param list ---v
  def testForFailure(blobKey: String) = filter() {
    Result {
      // v-- this has to be an assignment. Do anything you want with blobKey and it will fail
      val thisAssignmentCrashes = if (blobKey == null) "herp" else "derp"  
      
      "herp derp" // return whatever you want
    }
  }
}

// The key here is that it's parameterized I think.
abstract class Result[+T] {
  def instance: T
}

object Result {
  // operation could be a by-name parameter or a function
  def apply[T](operation: => T): Result[T] = {
    new Result[T] {
      def instance = operation
    }
  }
}

class Filter() {
  // Has to have default args
  def apply[A](openDatabase: Boolean = false)(operation: Result[A]): Result[A] = {
    Result {
      operation.instance
    }
  }
}