Remove lazy ObjC representation from String

Author: Alexis Beingessner

stdlib/public/core/Character.swift

@@ -183,7 +183,7 @@ public struct Character :
     }
     else {
       if let native = s._core.nativeBuffer,
-         native.start == s._core._baseAddress! {
+         native.start == s._core._baseAddress {
         _representation = .large(native._storage)
         return
       }

stdlib/public/core/String.swift

@@ -399,7 +399,6 @@ extension String : _ExpressibleByBuiltinUTF16StringLiteral {
         baseAddress: UnsafeMutableRawPointer(start),
         count: Int(utf16CodeUnitCount),
         elementShift: 1,
-        hasCocoaBuffer: false,
         owner: nil))
   }
 }
@@ -417,7 +416,6 @@ extension String : _ExpressibleByBuiltinStringLiteral {
           baseAddress: UnsafeMutableRawPointer(start),
           count: Int(utf8CodeUnitCount),
           elementShift: 0,
-          hasCocoaBuffer: false,
           owner: nil))
     }
     else {
@@ -753,7 +751,7 @@ extension String {
     }
 
 #if _runtime(_ObjC)
-    return _cocoaStringToSwiftString_NonASCII(
+    return String(_cocoaString:
       _stdlib_NSStringLowercaseString(self._bridgeToObjectiveCImpl()))
 #else
     return _nativeUnicodeLowercaseString(self)
@@ -792,7 +790,7 @@ extension String {
     }
 
 #if _runtime(_ObjC)
-    return _cocoaStringToSwiftString_NonASCII(
+    return String(_cocoaString:
       _stdlib_NSStringUppercaseString(self._bridgeToObjectiveCImpl()))
 #else
     return _nativeUnicodeUppercaseString(self)

stdlib/public/core/StringBridge.swift

@@ -77,9 +77,6 @@ public class _SwiftNativeNSString {}
 /// An `NSString` built around a slice of contiguous Swift `String` storage.
 public final class _NSContiguousString : _SwiftNativeNSString, _NSStringCore {
   public init(_ _core: _StringCore) {
-    _sanityCheck(
-      _core.hasContiguousStorage,
-      "_NSContiguousString requires contiguous storage")
     self._core = _core
     super.init()
   }
@@ -183,11 +180,6 @@ extension String {
   /// Same as `_bridgeToObjectiveC()`, but located inside the core standard
   /// library.
   public func _stdlib_binary_bridgeToObjectiveCImpl() -> AnyObject {
-    if let ns = _core.cocoaBuffer,
-        _swift_stdlib_CFStringGetLength(ns) == _core.count {
-      return ns
-    }
-    _sanityCheck(_core.hasContiguousStorage)
     return _NSContiguousString(_core)
   }
 

stdlib/public/core/StringComparable.swift

@@ -1,3 +1,4 @@
+
 //===----------------------------------------------------------------------===//
 //
 // This source file is part of the Swift.org open source project
@@ -73,17 +74,13 @@ extension String {
     // Note: this operation should be consistent with equality comparison of
     // Character.
 #if _runtime(_ObjC)
-    if self._core.hasContiguousStorage && rhs._core.hasContiguousStorage {
-      let lhsStr = _NSContiguousString(self._core)
-      let rhsStr = _NSContiguousString(rhs._core)
-      let res = lhsStr._unsafeWithNotEscapedSelfPointerPair(rhsStr) {
-        return Int(
-            _stdlib_compareNSStringDeterministicUnicodeCollationPointer($0, $1))
-      }
-      return res
+    let lhsStr = _NSContiguousString(self._core)
+    let rhsStr = _NSContiguousString(rhs._core)
+    let res = lhsStr._unsafeWithNotEscapedSelfPointerPair(rhsStr) {
+      return Int(
+          _stdlib_compareNSStringDeterministicUnicodeCollationPointer($0, $1))
     }
-    return Int(_stdlib_compareNSStringDeterministicUnicodeCollation(
-      _bridgeToObjectiveCImpl(), rhs._bridgeToObjectiveCImpl()))
+    return res
 #else
     switch (_core.isASCII, rhs._core.isASCII) {
     case (true, false):