     expectEqual(originalID, s.bufferID)
     s += "."
     expectNotEqual(originalID, s.bufferID)
+    unused += 0 // warning suppression
   }
 }
 

  var s = ""
  var s2 = s

  for i in 0..<20 {
    s += "x"
    s2 = s
  }
  expectLE(s.nativeCapacity, 34)
}


StringTests.test("COW/replaceSubrange/end") {
  // Check literal-to-heap reallocation.
  do {
    let str = "12345678"
    let literalIdentity = str.bufferID

    var slice = str[str.startIndex..<str.index(_nth: 7)]
