[stdlib] Restore a combination of 11 commits

...but remove all new uses of closures, to make things easier on the
optimizer.

Swift SVN r23183

stdlib/core/ArrayBuffer.swift

@@ -70,29 +70,28 @@ class _IndirectArrayBuffer {
     self.needsElementTypeCheck = false
   }
 
-  var buffer: AnyObject?
+  var buffer: AnyObject
   var isMutable: Bool
   var isCocoa: Bool
   var needsElementTypeCheck: Bool
   
   func getNativeBufferOf<T>(_: T.Type) -> _ContiguousArrayBuffer<T> {
     _sanityCheck(!isCocoa)
-    return _ContiguousArrayBuffer(
-      buffer != nil ? unsafeBitCast(buffer, _ContiguousArrayStorage<T>.self) : nil)
+    return _ContiguousArrayBuffer(unsafeDowncast(buffer))
   }
 
   func getCocoa() -> _NSArrayCoreType {
     _sanityCheck(isCocoa)
-    return unsafeBitCast(buffer!, _NSArrayCoreType.self)
+    return Builtin.bridgeFromRawPointer(Builtin.bridgeToRawPointer(buffer))
   }
 }
 
 public struct _ArrayBuffer<T> : _ArrayBufferType {
-  var storage: Builtin.NativeObject?
+  var storage: Builtin.NativeObject
 
   var indirect: _IndirectArrayBuffer {
     _sanityCheck(_isClassOrObjCExistential(T.self))
-    return Builtin.castFromNativeObject(storage!)
+    return Builtin.castFromNativeObject(storage)
   }
   
   public typealias Element = T
@@ -139,8 +138,7 @@ extension _ArrayBuffer {
   public
   init(_ source: NativeBuffer) {
     if !_isClassOrObjCExistential(T.self) {
-      self.storage
-        = (source._storage != nil) ? Builtin.castToNativeObject(source._storage!) : nil
+      self.storage = Builtin.castToNativeObject(source._storage)
     }
     else {
       self.storage = Builtin.castToNativeObject(
@@ -162,7 +160,7 @@ extension _ArrayBuffer {
       _isBridgedToObjectiveC(T.self),
       "Array element type is not bridged to ObjectiveC")
 
-    return _fastPath(_isNative) ? _native._asCocoaArray() : _nonNative!
+    return _fastPath(_isNative) ? _native._asCocoaArray() : _nonNative
   }
 
   var _hasMutableBuffer: Bool {
@@ -234,7 +232,7 @@ extension _ArrayBuffer {
         }
       }
       else if !subRange.isEmpty {
-        let ns = _nonNative!
+        let ns = _nonNative
         // Could be sped up, e.g. by using
         // enumerateObjectsAtIndexes:options:usingBlock:
         for i in subRange {
@@ -257,7 +255,7 @@ extension _ArrayBuffer {
       return _native._uninitializedCopy(subRange, target: target)
     }
 
-    let nonNative = _nonNative!
+    let nonNative = _nonNative
 
     let nsSubRange = SwiftShims._SwiftNSRange(
       location:subRange.startIndex,
@@ -292,7 +290,7 @@ extension _ArrayBuffer {
     let subRangeCount = Swift.count(subRange)
     
     // Look for contiguous storage in the NSArray
-    let cocoa = _CocoaArrayWrapper(nonNative!)
+    let cocoa = _CocoaArrayWrapper(nonNative)
     let start = cocoa.contiguousStorage(subRange)
     if start != nil {
       return _SliceBuffer(owner: nonNative, start: UnsafeMutablePointer(start),
@@ -326,7 +324,7 @@ extension _ArrayBuffer {
   public
   var count: Int {
     get {
-      return _fastPath(_isNative) ? _native.count : _nonNative!.count
+      return _fastPath(_isNative) ? _native.count : _nonNative.count
     }
     set {
       _sanityCheck(_isNative, "attempting to update count of Cocoa array")
@@ -348,7 +346,7 @@ extension _ArrayBuffer {
   /// How many elements the buffer can store without reallocation
   public
   var capacity: Int {
-    return _fastPath(_isNative) ? _native.capacity : _nonNative!.count
+    return _fastPath(_isNative) ? _native.capacity : _nonNative.count
   }
 
   /// Get/set the value of the ith element
@@ -361,7 +359,7 @@ extension _ArrayBuffer {
       if _fastPath(_isNative) {
         return _native[i]
       }
-      return unsafeBitCast(_nonNative!.objectAtIndex(i), T.self)
+      return unsafeBitCast(_nonNative.objectAtIndex(i), T.self)
     }
     
     nonmutating set {
@@ -383,7 +381,7 @@ extension _ArrayBuffer {
     body: (UnsafeBufferPointer<Element>)->R
   ) -> R {
     if _isClassOrObjCExistential(T.self) {
-      if _nonNative != nil {
+      if !_isNative {
         indirect.replaceStorage(_copyCollectionToNativeArrayBuffer(self))
       }
     }
@@ -411,8 +409,8 @@ extension _ArrayBuffer {
   
   /// An object that keeps the elements stored in this buffer alive
   public
-  var owner: AnyObject? {
-    return _fastPath(_isNative) ? _native._storage : _nonNative!
+  var owner: AnyObject {
+    return _fastPath(_isNative) ? _native._storage : _nonNative
   }
   
   /// A value that identifies the storage used by the buffer.  Two
@@ -422,11 +420,8 @@ extension _ArrayBuffer {
     if _isNative {
       return _native.identity
     }
-    else if let cocoa = _nonNative {
-      return unsafeAddressOf(cocoa)
-    }
     else {
-      return nil
+      return unsafeAddressOf(_nonNative)
     }
   }
   
@@ -474,11 +469,10 @@ extension _ArrayBuffer {
 
   /// Our native representation, if any.  If there's no native
   /// representation, the result is an empty buffer.
-  typealias _OptStorage = _ContiguousArrayStorage<T>?
   var _native: NativeBuffer {
     if !_isClassOrObjCExistential(T.self) {
-      return NativeBuffer(
-        unsafeBitCast(storage, _OptStorage.self))
+      let s: _ContiguousArrayStorageBase = Builtin.castFromNativeObject(storage)
+      return NativeBuffer(s)
     }
     else {
       let i = indirect
@@ -488,14 +482,11 @@ extension _ArrayBuffer {
     }
   }
 
-  var _nonNative: _NSArrayCoreType? {
-    if !_isClassOrObjCExistential(T.self) {
-      return nil
-    }
-    else {
-      let i = indirect
-      return _fastPath(!i.isCocoa) ? nil : i.getCocoa()
-    }
+  var _nonNative: _NSArrayCoreType {
+    _sanityCheck(_isClassOrObjCExistential(T.self))
+    let i = indirect
+    _sanityCheck(i.isCocoa)
+    return i.getCocoa()
   }
 }