[#2185] Remove useless warning in reverse compiler

[baloo]

see #2185

GET     /dummy       controllers.Application.dummy()
GET     /dummy1      controllers.Application.dummy()

will not generate warning

GET     /dummy       controllers.Application.dummy(foo: String)
GET     /dummy1      controllers.Application.dummy(foo = "bar")

will still generate warning

GET     /dummy1      controllers.Application.dummy(foo = "bar")
GET     /dummy       controllers.Application.dummy(foo: String)

will not generate warning

[gmethvin]

I think we can rewrite this a bit to make it more clear:

val parametersConstraints = (route.call.parameters.getOrElse(Nil).collect {
  case p if localNames.contains(p.name) && p.fixed.isDefined => s"${p.name} == ${p.fixed.get}"
}) match {
  case Seq() => ""
  case nonEmpty => s"if ${nonEmpty.mkString(" && ")}"
}

[gmethvin]

Can we add a test for this in RoutesCompilerSpec?

[baloo]

I'm sorry but I'm unable to test this in RoutesCompilerSpec, the warning occurs during the second phase of compilation (converting scala code into bytecode using scalac). I do not know the scala compiler internals, I have no idea how to test the output of scalac :(

[jroper]

Nice.

It would be possible to implement such a test, we have code that invokes the Scala compiler in the templates compiler specs, but it is a lot of overhead and quite annoying to maintain across different Scala versions because that API changes all the time, so I won't make you port that code to the routes compiler.