Conditional compilation for CountableRange variants of removeSubrange

These are no longer needed in Swift 4.2

Author: ole

Sources/SortedArray.swift

@@ -150,6 +150,18 @@ extension SortedArray {
         _elements.removeSubrange(bounds)
     }
 
+    // Starting with Swift 4.2, CountableRange and CountableClosedRange are typealiases for
+    // Range and ClosedRange, so these methods trigger "Invalid redeclaration" errors.
+    // Compile them only for older compiler versions.
+    // swift(3.1): Latest version of Swift 3 under the Swift 3 compiler.
+    // swift(3.2): Swift 4 compiler under Swift 3 mode.
+    // swift(3.3): Swift 4.1 compiler under Swift 3 mode.
+    // swift(3.4): Swift 4.2 compiler under Swift 3 mode.
+    // swift(4.0): Swift 4 compiler
+    // swift(4.1): Swift 4.1 compiler
+    // swift(4.1.50): Swift 4.2 compiler in Swift 4 mode
+    // swift(4.2): Swift 4.2 compiler
+    #if !swift(>=4.1.50)
     /// Removes the elements in the specified subrange from the array.
     ///
     /// - Parameter bounds: The range of the array to be removed. The
@@ -169,6 +181,7 @@ extension SortedArray {
     public mutating func removeSubrange(_ bounds: CountableClosedRange<Int>) {
         _elements.removeSubrange(bounds)
     }
+    #endif
 
     /// Removes the specified number of elements from the beginning of the
     /// array.

Tests/SortedArrayTests/SortedArrayTests.swift

@@ -273,6 +273,13 @@ class SortedArrayTests: XCTestCase {
         assertElementsEqual(sut, ["a","b"])
     }
 
+    func testRemoveCountableSubrange() {
+        var sut = SortedArray(unsorted: ["a","d","c","b"])
+        let countableRange: CountableRange<Int> = 2..<4
+        sut.removeSubrange(countableRange)
+        assertElementsEqual(sut, ["a","b"])
+    }
+
     func testRemoveFirst() {
         var sut = SortedArray(unsorted: [3,4,2,1])
         let removedElement = sut.removeFirst()
@@ -379,6 +386,7 @@ extension SortedArrayTests {
             ("testFilter", testFilter),
             ("testRemoveAtIndex", testRemoveAtIndex),
             ("testRemoveSubrange", testRemoveSubrange),
+            ("testRemoveCountableSubrange", testRemoveCountableSubrange),
             ("testRemoveFirst", testRemoveFirst),
             ("testRemoveFirstN", testRemoveFirstN),
             ("testRemoveLast", testRemoveLast),