Merge pull request swiftlang#1325 from odnoletkov/stdlib-interval-ove…

…rlaps [stdlib] Fixed IntervalType.overlaps for empty interval case
athas · Feb 16, 2016 · 532d36d · 532d36d
2 parents d7d87a1 + 9fffeda
commit 532d36d
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diff --git a/stdlib/public/core/Interval.swift.gyb b/stdlib/public/core/Interval.swift.gyb
@@ -167,12 +167,13 @@ extension ClosedInterval {
 }
 
 extension IntervalType {
-  /// Returns `true` if `lhs` and `rhs` have a non-empty intersection.
+  /// Returns `true` iff `lhs` and `rhs` have a non-empty intersection.
   @warn_unused_result
   public func overlaps<
     I: IntervalType where I.Bound == Bound
   >(other: I) -> Bool {
-    return contains(other.start) || other.contains(start)
+    return (!other.isEmpty && contains(other.start))
+      || (!isEmpty && other.contains(start))
   }
 }
 

diff --git a/test/1_stdlib/Interval.swift b/test/1_stdlib/Interval.swift
@@ -131,6 +131,11 @@ IntervalTestSuite.test("Overlaps") {
   expectOverlaps(true, 0..<20, 5...10)
   expectOverlaps(true, 0...20, 5..<10)
   expectOverlaps(true, 0...20, 5...10)
+
+  // 0-0, 0-5
+  expectOverlaps(false, 0..<0, 0..<5)
+  expectOverlaps(false, 0..<0, 0...5)
+
 }
 
 IntervalTestSuite.test("Emptiness") {