Merge pull request #4716 from Ichoran/issue/9388

SI-9388  Fix Range behavior around Int.MaxValue

4 files changed, 55 insertions, 4 deletions

diff --git a/test/files/run/t4658.check b/test/files/run/t4658.check
index bb6405175e..3bc52daef3 100644
--- a/test/files/run/t4658.check
+++ b/test/files/run/t4658.check
@@ -1,5 +1,5 @@
 Ranges:
-1073741824
+-1073741824
 1073741824
 0
 0
@@ -20,7 +20,7 @@ Ranges:
 -10
 IntRanges:
 -1073741824
--1073741824
+1073741824
 0
 0
 55
@@ -78,3 +78,6 @@ BigIntRanges:
 -24
 -30
 -10
+BigInt agrees with Long: true
+Long agrees with Int when rounded: true
+Numeric Int agrees with Range: true
diff --git a/test/files/run/t4658.scala b/test/files/run/t4658.scala
index 8c07c50694..7fc6d4584c 100644
--- a/test/files/run/t4658.scala
+++ b/test/files/run/t4658.scala
@@ -2,6 +2,7 @@ import scala.collection.immutable.NumericRange
 //#4658
 object Test {
 
+  // Only works for Int values!  Need to rethink explicit otherwise.
   case class R(start: Int, end: Int, step: Int = 1, inclusive: Boolean = true)
 
   val rangeData = Array(
@@ -28,6 +29,14 @@ object Test {
     numericLongRanges.foreach{range => println(range.sum)}
     println("BigIntRanges:")
     numericBigIntRanges.foreach{range => println(range.sum)}
+    println("BigInt agrees with Long: " + 
+      (numericLongRanges zip numericBigIntRanges).forall{ case (lr, bir) => lr.sum == bir.sum }
+    )
+    println("Long agrees with Int when rounded: " + 
+      (numericLongRanges zip numericIntRanges).forall{ case (lr, ir) => lr.sum.toInt == ir.sum }
+    )
+    println("Numeric Int agrees with Range: " +
+      (numericIntRanges zip ranges).forall{ case (ir, r) => ir.sum == r.sum }
+    )
   }
-
 }
\ No newline at end of file
diff --git a/test/files/scalacheck/range.scala b/test/files/scalacheck/range.scala
index 493083a51f..ac24b52f8d 100644
--- a/test/files/scalacheck/range.scala
+++ b/test/files/scalacheck/range.scala
@@ -134,7 +134,22 @@ abstract class RangeTest(kind: String) extends Properties("Range "+kind) {
     val expected = r.length match {
       case 0 => 0
       case 1 => r.head
-      case _ => ((r.head + r.last).toLong * r.length  / 2).toInt
+      case x if x < 1000 => 
+        // Explicit sum, to guard against having the same mistake in both the
+        // range implementation and test implementation of sum formula.
+        // (Yes, this happened before.)
+        var i = r.head
+        var s = 0L
+        var n = x
+        while (n > 0) {
+          s += i
+          i += r.step
+          n -= 1
+        }
+        s.toInt
+      case _ =>
+        // Make sure head + last doesn't overflow!
+        ((r.head.toLong + r.last) * r.length  / 2).toInt
     }
 //   println("size: " + r.length)
 //   println("expected: " + expected)
diff --git a/test/junit/scala/collection/immutable/RangeConsistencyTest.scala b/test/junit/scala/collection/immutable/RangeConsistencyTest.scala
index 135796979d..760498c162 100644
--- a/test/junit/scala/collection/immutable/RangeConsistencyTest.scala
+++ b/test/junit/scala/collection/immutable/RangeConsistencyTest.scala
@@ -148,4 +148,28 @@ class RangeConsistencyTest {
     val bdRange = bd(-10.0) until bd(0.0) by bd(4.5)
     assert( bdRange sameElements List(bd(-10.0), bd(-5.5), bd(-1.0)) )
   }
+
+  @Test
+  def test_SI9388()  {
+    val possiblyNotDefaultNumeric = new scala.math.Numeric[Int] {
+      def fromInt(x: Int) = x
+      def minus(x: Int, y: Int): Int = x - y
+      def negate(x: Int): Int = -x
+      def plus(x: Int, y: Int): Int = x + y
+      def times(x: Int, y: Int): Int = x*y
+      def toDouble(x: Int): Double = x.toDouble
+      def toFloat(x: Int): Float = x.toFloat
+      def toInt(x: Int): Int = x
+      def toLong(x: Int): Long = x.toLong
+      def compare(x: Int, y: Int) = x compare y
+    }
+    val r = (Int.MinValue to Int.MaxValue by (1<<23))
+    val nr = NumericRange(Int.MinValue, Int.MaxValue, 1 << 23)
+    assert({ var i = 0; r.foreach(_ => i += 1); i } == 512)
+    assert({ var i = 0; nr.foreach(_ => i += 1); i } == 512)
+    assert(r.sum == Int.MinValue)
+    assert(nr.sum == Int.MinValue)
+    assert(r.sum(possiblyNotDefaultNumeric) == Int.MinValue)
+    assert(nr.sum(possiblyNotDefaultNumeric) == Int.MinValue)
+  }
 }