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Structural types do not inspect bounds; unsoundness results #5378

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scabug opened this Issue Jan 16, 2012 · 8 comments

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scabug commented Jan 16, 2012

Ring the big bell.

class Coll[+T] {
  def contains = new { def apply[T1 <: T](value: T1) = ??? }
}

object Test {
  def main(args: Array[String]): Unit = {
    val xs = new Coll[List[String]]
    val ys: Coll[Traversable[String]] = xs
    
    println(ys contains Nil)
    // java.lang.NoSuchMethodException: Coll$$anon$1.apply(scala.collection.Traversable)
    //  at java.lang.Class.getMethod(Class.java:1605)
    //  at Test$.reflMethod$Method1(a.scala:14)
    //  at Test$.main(a.scala:14)
    //  at Test.main(a.scala)
  }
}

It should fail the way this does:

def contains = new { def apply(value: T) = ??? } 

./a.scala:2: error: Parameter type in structural refinement may not refer to an abstract type defined outside that refinement
  def contains = new { def apply(value: T) = ??? } 
                           ^
one error found
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scabug commented Jan 16, 2012

Imported From: https://issues.scala-lang.org/browse/SI-5378?orig=1
Reporter: @paulp
Affected Versions: 2.10.0
See #967, #5517

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scabug commented Jan 16, 2012

@paulp said:
You really want this one? It'll take me five minutes to fix it, I was just letting it age under scala reviewer for a minute.

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scabug commented Jan 16, 2012

@adriaanm said:
please, have at it!

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scabug commented May 9, 2012

@phaller said:
Added test in 71c17a649e.

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scabug commented Jan 2, 2013

@paulp said:
Patch pending.

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scabug commented Jan 22, 2013

@adriaanm said:
TODO: backport 31f073c0eb to 2.10.x

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scabug commented Jan 28, 2013

@adriaanm said (edited on Jan 28, 2013 11:07:14 PM UTC):
2.11: scala/scala#1873
2.10.1: scala/scala#2000

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scabug commented Feb 1, 2013

@paulp said:
110b54a575278

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