Range.contains is wrong

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scala> (Int.MinValue until 0).contains(4)
res18: Boolean = true

scala> (0 to Int.MaxValue).contains(4)
res21: Boolean = false

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Imported From: https://issues.scala-lang.org/browse/SI-6736?orig=1
Reporter: @Atry
Affected Versions: 2.10.0-RC3

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Daniel Vashchilenko (skydan) said:
Scala 2.9.2 is not affected as it won't evaluate:

java.lang.IllegalArgumentException: -2147483648 until 0 by 1: seqs cannot contain more than Int.MaxValue elements.

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@soc said:
It could be possible that the issue was introduced when Range was made more lazy to allow “too large” start/end inputs where by is used afterwards to make the size less than Int.MaxValue again, like {{{Int.MinValue to Int.MaxValue by 10}}}.

contains probably doesn't check the inputs, because it still assumes that an invalid Range would have thrown en exception earlier already as it has been the case in older versions.

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Daniel Vashchilenko (skydan) said (edited on Dec 1, 2012 4:52:32 PM UTC):
contains seems to be good to me. It uses step-aware isWithinBoundaries and then checks that the value is n*step away from the start.

final def contains(x: Int) = isWithinBoundaries(x) && ((x - start) % step == 0)

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@soc said:
I'm not sure that's the issue here. If not otherwise specified, step is always 1. In the given examples the range is ascending anyways, so the check just needs to get fixed properly. See also #6747. Or am I missing something?

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Sergii Zashchelkin (sergz72) said:
Problem is in isWithinBoundaries function:

  // Tests whether a number is within the endpoints, without testing
  // whether it is a member of the sequence (i.e. when step > 1.)
  private def isWithinBoundaries(elem: Int) = !isEmpty && (
    (step > 0 && start <= elem && elem <= last ) ||
    (step < 0 &&  last <= elem && elem <= start)
  )
``

this function uses Range.last function which defined as follows:

```scala
  override def last = if (isEmpty) Nil.last else lastElement

and lastElement function have following definition:

  final val lastElement     = start + (numRangeElements - 1) * step

and numRangeElements have following definition:

  final val numRangeElements: Int = {
    if (step == 0) throw new IllegalArgumentException("step cannot be 0.")
    else if (isEmpty) 0
    else {
      val len = longLength
      if (len > scala.Int.MaxValue) -1
      else len.toInt
    }
  }

so if length of Range object > scala.Int.MaxValue it returns -1

and lastElement will be calculated as start + (-1 - 1) * step and this equals (step = 1) to start - 2

I propose to use Range.end instead of Range.last in the isWithinBoundaries function

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Daniel Vashchilenko (skydan) said:
isWithinBoundaries returns true if the number is between the start and the last element. It does not check that the number is a part of the Range. This is the expected behavior as far as I understand.

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@adriaanm said:
Alex, could you have a look?

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@JamesIry said:
2.10.2 is about to be cut. Kicking down the road and un-assigning to foster work stealing.

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@adriaanm said:
scala/scala#3437