CountableRange is deprecated, renamed to Range

- Replace NSRange.toCountableRange() with Range.init?(_:)

- Update Test cases.

Author: spevans

Foundation/Data.swift

@@ -1003,7 +1003,7 @@ public struct Data : ReferenceConvertible, Equatable, Hashable, RandomAccessColl
 
     public typealias Index = Int
     // FIXME: switch back to Range once swift 5.0 branch has PR #13342
-    public typealias Indices = CountableRange<Int>
+    public typealias Indices = Range<Int>
 
     @_versioned internal var _backing : _DataStorage
     @_versioned internal var _sliceRange: Range<Index>
@@ -1744,7 +1744,7 @@ public struct Data : ReferenceConvertible, Equatable, Hashable, RandomAccessColl
         return i + 1
     }
 
-    public var indices: CountableRange<Int> {
+    public var indices: Range<Int> {
         @inline(__always)
         get {
             return startIndex..<endIndex

Foundation/IndexSet.swift

@@ -105,7 +105,7 @@ public struct IndexSet : ReferenceConvertible, Equatable, BidirectionalCollectio
             return IndexingIterator(_elements: self)
         }
 
-        public subscript(index : Index) -> CountableRange<IndexSet.Element> {
+        public subscript(index : Index) -> Range<IndexSet.Element> {
             let indexSetRange = indexSet._range(at: index)
             if let intersectingRange = intersectingRange {
                 return Swift.max(intersectingRange.lowerBound, indexSetRange.lowerBound)..<Swift.min(intersectingRange.upperBound, indexSetRange.upperBound)
@@ -722,8 +722,8 @@ private struct IndexSetBoundaryIterator : IteratorProtocol {
 
     private var i1: IndexSet.RangeView.Iterator
     private var i2: IndexSet.RangeView.Iterator
-    private var i1Range: CountableRange<Element>?
-    private var i2Range: CountableRange<Element>?
+    private var i1Range: Range<Element>?
+    private var i2Range: Range<Element>?
     private var i1UsedLower: Bool
     private var i2UsedLower: Bool
 

Foundation/NSArray.swift

@@ -264,7 +264,7 @@ open class NSArray : NSObject, NSCopying, NSMutableCopying, NSSecureCoding, NSCo
             return
         }
 
-        objects += range.toCountableRange()!.map { self[$0] }
+        objects += Range(range)!.map { self[$0] }
     }
 
     open func index(of anObject: Any) -> Int {
@@ -874,7 +874,7 @@ open class NSMutableArray : NSArray {
         if type(of: self) === NSMutableArray.self {
             _storage.removeSubrange(Range(range)!)
         } else {
-            for idx in range.toCountableRange()!.reversed() {
+            for idx in Range(range)!.reversed() {
                 removeObject(at: idx)
             }
         }

Foundation/NSOrderedSet.swift

@@ -312,7 +312,7 @@ extension NSOrderedSet {
     public convenience init(array set: [Any], range: NSRange, copyItems flag: Bool) {
         var objects = set
 
-        if let range = range.toCountableRange(), range.count != set.count || flag {
+        if let range = Range(range), range.count != set.count || flag {
             objects = [Any]()
             for index in range.indices {
                 let object = set[index]
@@ -461,7 +461,7 @@ extension NSMutableOrderedSet {
     }
 
     open func replaceObjects(in range: NSRange, with objects: UnsafePointer<AnyObject>!, count: Int) {
-        if let range = range.toCountableRange() {
+        if let range = Range(range) {
             let buffer = UnsafeBufferPointer(start: objects, count: count)
             for (indexLocation, index) in range.indices.lazy.reversed().enumerated() {
                 let object = buffer[indexLocation]
@@ -478,7 +478,7 @@ extension NSMutableOrderedSet {
     }
 
     open func removeObjects(in range: NSRange) {
-        if let range = range.toCountableRange() {
+        if let range = Range(range) {
             for index in range.indices.lazy.reversed() {
                 removeObject(at: index)
             }

Foundation/NSRange.swift

@@ -352,11 +352,6 @@ extension NSRange {
         location = x.lowerBound
         length = x.count
     }
-    
-    internal func toCountableRange() -> CountableRange<Int>? {
-        if location == NSNotFound { return nil }
-        return location..<(location+length)
-    }
 }
 
 extension NSRange: NSSpecialValueCoding {