pattern matching does not wlways check outer

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Aladdin: [http://scala-webapps.epfl.ch/bugtracking/bugs/displayItem.do?id=1159 bug 1159]

== Code ==

class Outer {
  case class Foo(x: int, y: int) {
    override def equals(other: Any) = other match {
      case Outer.this.Foo(`x`, `y`) => true
      case _ => false
    }
  }
}

object Test extends Application {
  val o1 = new Outer
  val o2 = new Outer
  val x: Any = o1.Foo(1, 2)
  val y: Any = o2.Foo(1, 2)
  println(x equals y)
  x match {
    case o2.Foo(x, y) => println("error 1")
    case o1.Foo(x, y) => println("OK")
    case _ => println("error 2")
  }
}

== What happened ==

true
OK

== What expected ==

false
OK

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Imported From: https://issues.scala-lang.org/browse/SI-2?orig=1
Reporter: @burakemir

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@burakemir said:
(meta) haha, if you don't assign to anybody, trac picks "dubochet" (/meta)

This ticket is from open aladdin bug #1159.

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@dubochet said:
When fixing this, it's tricky not too insert too many outer tests. For instance, if other' in equals' had type Outer.this.Foo' instead of Any', there should be no outer test, because we know statically that the outer pointers must be the same (if not, the types would not work out) [martin]

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@burakemir said:
I'd rather uniformly generate outer tests everywhere and have a later phase figure out which tests are necessary and which are not. There is already magic that translates isInstanceOf[A with B] to isInstanceOf[A]&&isInstanceOf[B], these things are independent of pattern matching.

Alternatively, I would like to have an API method to which I can give source and destination type as well as the context (in the form of the owner symbol), and it figures out what I have to do.

My present outer generation is hard to understand (for myself and others), because pattern matching happens at the same time as explicitouter. Putting additional logic in there is not going to make it simpler.

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@odersky said:
I have added a method needsOuterTest to Types.scala. If you call it from the pattern matcher, this should do the trick.

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@burakemir said:
fixed in tags R_2_6_0-RC2 in r12757
fixed in trunk, r12758

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@odersky said:
Milestone 2.6.0 deleted