   ///
   /// Returns the fully-initialized buffer. `self` is reset to contain an
   /// empty buffer and cannot be used afterward.
+  @inline(__always) // For performance reasons.
   mutating func finish() -> _ContiguousArrayBuffer<Element> {
     // Adjust the initialized count of the buffer.
     result.count = result.capacity - remainingCapacity


  /// Initialize the buffer with an initial size of `initialCapacity`
  /// elements.
  init(initialCapacity: Int) {
    if initialCapacity == 0 {
      result = _ContiguousArrayBuffer()

  }

  /// Add an element to the buffer, which must have remaining capacity.
  @inline(__always) // For performance reasons.
  mutating func addWithExistingCapacity(element: Element) {
    _sanityCheck(remainingCapacity > 0,
      "_UnsafePartiallyInitializedContiguousArrayBuffer has no more capacity")
