Improve forward reference handling?

[liufengyun]

@cluelessjoe

btw another issue we spoke of recently in Better implicit search errors:

import org.scalatest.FunSuite
import play.api.libs.json.{Format, Json}

class ImplicitOrderingTest extends FunSuite {

  implicit val BarFormat: Format[Bar] = Json.format
  implicit val FooFormat: Format[Foo] = Json.format
  test("Writing Bar - right order: compile and crash at runtime") {

    assert(BarFormat.writes(Bar(Foo(1))).toString() === """{"f":{"i":1}}""")  //throws!!
  }

}

case class Foo(i: Int)

case class Bar(f: Foo)

This compiles but throws NPE at runtime.

Thanks for letting us know the case. Yes, the checker will be able to catch the bug and issue an error.