[stdlib] Make protocol _NSArrayCore internal

These shadow protocols don’t add any real type safety, and exposing them in the ABI seems unnecessary.

stdlib/public/SDK/Foundation/NSArray.swift

@@ -43,9 +43,7 @@ extension Array : _ObjectiveCBridgeable {
     //
     // The bug is fixed in: OS X 10.11.0, iOS 9.0, all versions of tvOS
     // and watchOS.
-    self = Array(
-      _immutableCocoaArray:
-        unsafeBitCast(_cocoaArray.copy() as AnyObject, to: _NSArrayCore.self))
+    self = Array(_immutableCocoaArray: _cocoaArray.copy() as AnyObject)
   }
 
   @_semantics("convertToObjectiveC")

stdlib/public/core/Array.swift

@@ -1728,7 +1728,7 @@ extension Array {
 // to do the bridging in an ABI safe way. Even though this looks useless,
 // DO NOT DELETE!
 @usableFromInline internal
-func _bridgeCocoaArray<T>(_ _immutableCocoaArray: _NSArrayCore) -> Array<T> {
+func _bridgeCocoaArray<T>(_ _immutableCocoaArray: AnyObject) -> Array<T> {
   return Array(_buffer: _ArrayBuffer(nsArray: _immutableCocoaArray))
 }
 
@@ -1764,7 +1764,7 @@ extension Array {
   /// * `Element` is bridged verbatim to Objective-C (i.e.,
   ///   is a reference type).
   @inlinable
-  public init(_immutableCocoaArray: _NSArrayCore) {
+  public init(_immutableCocoaArray: AnyObject) {
     self = _bridgeCocoaArray(_immutableCocoaArray)
   }
 }

stdlib/public/core/ArrayBuffer.swift

@@ -20,7 +20,7 @@ import SwiftShims
 
 @usableFromInline
 internal typealias _ArrayBridgeStorage
-  = _BridgeStorage<__ContiguousArrayStorageBase, _NSArrayCore>
+  = _BridgeStorage<__ContiguousArrayStorageBase, AnyObject>
 
 @usableFromInline
 @_fixed_layout
@@ -33,7 +33,7 @@ internal struct _ArrayBuffer<Element> : _ArrayBufferProtocol {
   }
 
   @inlinable
-  internal init(nsArray: _NSArrayCore) {
+  internal init(nsArray: AnyObject) {
     _sanityCheck(_isClassOrObjCExistential(Element.self))
     _storage = _ArrayBridgeStorage(objC: nsArray)
   }
@@ -121,8 +121,8 @@ extension _ArrayBuffer {
   ///
   /// O(1) if the element type is bridged verbatim, O(*n*) otherwise.
   @inlinable
-  internal func _asCocoaArray() -> _NSArrayCore {
-    return _fastPath(_isNative) ? _native._asCocoaArray() : _nonNative
+  internal func _asCocoaArray() -> AnyObject {
+    return _fastPath(_isNative) ? _native._asCocoaArray() : _nonNative.buffer
   }
 
   /// If this buffer is backed by a uniquely-referenced mutable
@@ -175,8 +175,7 @@ extension _ArrayBuffer {
       )
     }
     else {
-      let ns = _nonNative
-      let element = ns.objectAt(index)
+      let element = _nonNative[index]
       precondition(
         element is Element,
         """
@@ -216,26 +215,12 @@ extension _ArrayBuffer {
     if _fastPath(_isNative) {
       return _native._copyContents(subRange: bounds, initializing: target)
     }
-
-    let nonNative = _nonNative
-
-    let nsSubRange = SwiftShims._SwiftNSRange(
-      location: bounds.lowerBound,
-      length: bounds.upperBound - bounds.lowerBound)
-
-    let buffer = UnsafeMutableRawPointer(target).assumingMemoryBound(
-      to: AnyObject.self)
-    
-    // Copies the references out of the NSArray without retaining them
-    nonNative.getObjects(buffer, range: nsSubRange)
-    
-    // Make another pass to retain the copied objects
-    var result = target
-    for _ in bounds {
-      result.initialize(to: result.pointee)
-      result += 1
-    }
-    return result
+    let buffer = UnsafeMutableRawPointer(target)
+      .assumingMemoryBound(to: AnyObject.self)
+    let result = _nonNative._copyContents(
+      subRange: bounds,
+      initializing: buffer)
+    return UnsafeMutableRawPointer(result).assumingMemoryBound(to: Element.self)
   }
 
   /// Returns a `_SliceBuffer` containing the given sub-range of elements in
@@ -244,45 +229,10 @@ extension _ArrayBuffer {
   internal subscript(bounds: Range<Int>) -> _SliceBuffer<Element> {
     get {
       _typeCheck(bounds)
-
       if _fastPath(_isNative) {
         return _native[bounds]
       }
-
-      let boundsCount = bounds.count
-      if boundsCount == 0 {
-        return _SliceBuffer(
-          _buffer: _ContiguousArrayBuffer<Element>(),
-          shiftedToStartIndex: bounds.lowerBound)
-      }
-
-      // Look for contiguous storage in the NSArray
-      let nonNative = self._nonNative
-      let cocoa = _CocoaArrayWrapper(nonNative)
-      let cocoaStorageBaseAddress = cocoa.contiguousStorage(self.indices)
-
-      if let cocoaStorageBaseAddress = cocoaStorageBaseAddress {
-        let basePtr = UnsafeMutableRawPointer(cocoaStorageBaseAddress)
-          .assumingMemoryBound(to: Element.self)
-        return _SliceBuffer(
-          owner: nonNative,
-          subscriptBaseAddress: basePtr,
-          indices: bounds,
-          hasNativeBuffer: false)
-      }
-
-      // No contiguous storage found; we must allocate
-      let result = _ContiguousArrayBuffer<Element>(
-        _uninitializedCount: boundsCount, minimumCapacity: 0)
-
-      // Tell Cocoa to copy the objects into our storage
-      cocoa.buffer.getObjects(
-        UnsafeMutableRawPointer(result.firstElementAddress)
-          .assumingMemoryBound(to: AnyObject.self),
-        range: _SwiftNSRange(location: bounds.lowerBound, length: boundsCount))
-
-      return _SliceBuffer(
-        _buffer: result, shiftedToStartIndex: bounds.lowerBound)
+      return _nonNative[bounds].unsafeCastElements(to: Element.self)
     }
     set {
       fatalError("not implemented")
@@ -392,7 +342,7 @@ extension _ArrayBuffer {
       )
     } else {
       // ObjC arrays do their own subscript checking.
-      element = _nonNative.objectAt(i)
+      element = _nonNative[i]
       precondition(
         element is Element,
         """
@@ -460,7 +410,7 @@ extension _ArrayBuffer {
   /// An object that keeps the elements stored in this buffer alive.
   @inlinable
   internal var owner: AnyObject {
-    return _fastPath(_isNative) ? _native._storage : _nonNative
+    return _fastPath(_isNative) ? _native._storage : _nonNative.buffer
   }
   
   /// An object that keeps the elements stored in this buffer alive.
@@ -481,7 +431,8 @@ extension _ArrayBuffer {
       return _native.identity
     }
     else {
-      return UnsafeRawPointer(Unmanaged.passUnretained(_nonNative).toOpaque())
+      return UnsafeRawPointer(
+        Unmanaged.passUnretained(_nonNative.buffer).toOpaque())
     }
   }
   
@@ -550,11 +501,11 @@ extension _ArrayBuffer {
   }
 
   @inlinable
-  internal var _nonNative: _NSArrayCore {
+  internal var _nonNative: _CocoaArrayWrapper {
     @inline(__always)
     get {
       _sanityCheck(_isClassOrObjCExistential(Element.self))
-      return _storage.objCInstance
+      return _CocoaArrayWrapper(_storage.objCInstance)
     }
   }
 }

stdlib/public/core/CocoaArray.swift

@@ -21,29 +21,76 @@
 #if _runtime(_ObjC)
 import SwiftShims
 
-/// A wrapper around any `_NSArrayCore` that gives it
-/// `Collection` conformance.  Why not make
-/// `_NSArrayCore` conform directly?  It's a class, and I
-/// don't want to pay for the dynamic dispatch overhead.
+/// A wrapper around any `_NSArrayCore` (represented as AnyObject) that gives it
+/// `Collection` conformance.  Why not make `_NSArrayCore` conform directly?
+/// It's a class, and I don't want to pay for the dynamic dispatch overhead.
 @usableFromInline
 @_fixed_layout
 internal struct _CocoaArrayWrapper : RandomAccessCollection {
   @usableFromInline
   typealias Indices = Range<Int>
 
+  @usableFromInline
+  internal var buffer: AnyObject
+
+  @usableFromInline @_transparent
+  internal init(_ buffer: AnyObject) {
+    self.buffer = buffer
+  }
+
+  internal var core: _NSArrayCore {
+    @inline(__always) get {
+      return unsafeBitCast(buffer, to: _NSArrayCore.self)
+    }
+  }
+
   @inlinable
   internal var startIndex: Int {
     return 0
   }
 
-  @inlinable
+  @usableFromInline
   internal var endIndex: Int {
-    return buffer.count
+    return core.count
   }
 
-  @inlinable
+  @usableFromInline
   internal subscript(i: Int) -> AnyObject {
-    return buffer.objectAt(i)
+    return core.objectAt(i)
+  }
+
+  @usableFromInline
+  internal subscript(bounds: Range<Int>) -> _SliceBuffer<AnyObject> {
+    let boundsCount = bounds.count
+    if boundsCount == 0 {
+      return _SliceBuffer(
+        _buffer: _ContiguousArrayBuffer<AnyObject>(),
+        shiftedToStartIndex: bounds.lowerBound)
+    }
+
+    // Look for contiguous storage in the NSArray
+    let cocoaStorageBaseAddress = self.contiguousStorage(self.indices)
+
+    if let cocoaStorageBaseAddress = cocoaStorageBaseAddress {
+      return _SliceBuffer(
+        owner: self.buffer,
+        subscriptBaseAddress: cocoaStorageBaseAddress,
+        indices: bounds,
+        hasNativeBuffer: false)
+    }
+
+    // No contiguous storage found; we must allocate
+    let result = _ContiguousArrayBuffer<AnyObject>(
+      _uninitializedCount: boundsCount,
+      minimumCapacity: 0)
+
+    // Tell Cocoa to copy the objects into our storage
+    core.getObjects(
+      UnsafeMutableRawPointer(result.firstElementAddress)
+      .assumingMemoryBound(to: AnyObject.self),
+      range: _SwiftNSRange(location: bounds.lowerBound, length: boundsCount))
+
+    return _SliceBuffer(_buffer: result, shiftedToStartIndex: bounds.lowerBound)
   }
 
   /// Returns a pointer to the first element in the given non-empty `subRange`
@@ -56,7 +103,6 @@ internal struct _CocoaArrayWrapper : RandomAccessCollection {
   ///   is sometimes conservative and may return `nil` even when
   ///   contiguous storage exists, e.g., if array doesn't have a smart
   /// implementation of countByEnumerating.
-  @inlinable
   internal func contiguousStorage(
     _ subRange: Range<Int>
   ) -> UnsafeMutablePointer<AnyObject>?
@@ -69,7 +115,7 @@ internal struct _CocoaArrayWrapper : RandomAccessCollection {
     // acceptable conservative behavior, but could potentially be
     // optimized for other cases.
     let contiguousCount = withUnsafeMutablePointer(to: &enumerationState) {
-      self.buffer.countByEnumerating(with: $0, objects: nil, count: 0)
+      core.countByEnumerating(with: $0, objects: nil, count: 0)
     }
 
     return contiguousCount >= subRange.upperBound
@@ -79,12 +125,25 @@ internal struct _CocoaArrayWrapper : RandomAccessCollection {
       : nil
   }
 
-  @usableFromInline @_transparent
-  internal init(_ buffer: _NSArrayCore) {
-    self.buffer = buffer
-  }
-
   @usableFromInline
-  internal var buffer: _NSArrayCore
+  __consuming internal func _copyContents(
+    subRange bounds: Range<Int>,
+    initializing target: UnsafeMutablePointer<AnyObject>
+  ) -> UnsafeMutablePointer<AnyObject> {
+    let nsSubRange = SwiftShims._SwiftNSRange(
+      location: bounds.lowerBound,
+      length: bounds.upperBound - bounds.lowerBound)
+
+    // Copies the references out of the NSArray without retaining them
+    core.getObjects(target, range: nsSubRange)
+
+    // Make another pass to retain the copied objects
+    var result = target
+    for _ in bounds {
+      result.initialize(to: result.pointee)
+      result += 1
+    }
+    return result
+  }
 }
 #endif

stdlib/public/core/ContiguousArrayBuffer.swift

@@ -431,7 +431,7 @@ internal struct _ContiguousArrayBuffer<Element> : _ArrayBufferProtocol {
   ///
   /// - Complexity: O(1).
   @inlinable
-  internal __consuming func _asCocoaArray() -> _NSArrayCore {
+  internal __consuming func _asCocoaArray() -> AnyObject {
     if count == 0 {
       return _emptyArrayStorage
     }

stdlib/public/core/ShadowProtocols.swift

@@ -58,8 +58,7 @@ public protocol _NSCopying : _ShadowProtocol {
 /// Covers a set of operations everyone needs to implement in order to
 /// be a useful `NSArray` subclass.
 @unsafe_no_objc_tagged_pointer @objc
-public protocol _NSArrayCore :
-    _NSCopying, _NSFastEnumeration {
+internal protocol _NSArrayCore: _NSCopying, _NSFastEnumeration {
 
   @objc(objectAtIndex:)
   func objectAt(_ index: Int) -> AnyObject
@@ -185,8 +184,4 @@ internal protocol _NSNumber {
   var objCType: UnsafePointer<Int8> { get }
 }
 
-#else
-
-public protocol _NSArrayCore {}
-
 #endif

test/SILOptimizer/dead_array_elim.sil

@@ -64,7 +64,7 @@ bb0(%0 : $TrivialDestructor):
   store %0 to %10 : $*TrivialDestructor
   %13 = struct_extract %5 : $Array<TrivialDestructor>, #Array._buffer
   %14 = struct_extract %13 : $_ArrayBuffer<TrivialDestructor>, #_ArrayBuffer._storage
-  %15 = struct_extract %14 : $_BridgeStorage<__ContiguousArrayStorageBase, _NSArrayCore>, #_BridgeStorage.rawValue
+  %15 = struct_extract %14 : $_BridgeStorage<__ContiguousArrayStorageBase, AnyObject>, #_BridgeStorage.rawValue
   strong_retain %0 : $TrivialDestructor
   strong_release %15 : $Builtin.BridgeObject
 // CHECK-NEXT: tuple ()
@@ -91,7 +91,7 @@ bb0(%0 : $TrivialDestructor):
   %7 = pointer_to_address %6 : $Builtin.RawPointer to [strict] $*TrivialDestructor
   %13 = struct_extract %5 : $Array<TrivialDestructor>, #Array._buffer
   %14 = struct_extract %13 : $_ArrayBuffer<TrivialDestructor>, #_ArrayBuffer._storage
-  %15 = struct_extract %14 : $_BridgeStorage<__ContiguousArrayStorageBase, _NSArrayCore>, #_BridgeStorage.rawValue
+  %15 = struct_extract %14 : $_BridgeStorage<__ContiguousArrayStorageBase, AnyObject>, #_BridgeStorage.rawValue
   strong_retain %0 : $TrivialDestructor
   strong_release %15 : $Builtin.BridgeObject
 
@@ -121,7 +121,7 @@ bb0(%0 : $TrivialDestructor):
   %6 = tuple_extract %4 : $(Array<TrivialDestructor>, Builtin.RawPointer), 1
   %13 = struct_extract %5 : $Array<TrivialDestructor>, #Array._buffer
   %14 = struct_extract %13 : $_ArrayBuffer<TrivialDestructor>, #_ArrayBuffer._storage
-  %15 = struct_extract %14 : $_BridgeStorage<__ContiguousArrayStorageBase, _NSArrayCore>, #_BridgeStorage.rawValue
+  %15 = struct_extract %14 : $_BridgeStorage<__ContiguousArrayStorageBase, AnyObject>, #_BridgeStorage.rawValue
   cond_br undef, bb1, bb2
 
 bb1:
@@ -159,7 +159,7 @@ bb1:
   %5 = tuple_extract %4 : $(Array<TrivialDestructor>, Builtin.RawPointer), 0
   %13 = struct_extract %5 : $Array<TrivialDestructor>, #Array._buffer
   %14 = struct_extract %13 : $_ArrayBuffer<TrivialDestructor>, #_ArrayBuffer._storage
-  %15 = struct_extract %14 : $_BridgeStorage<__ContiguousArrayStorageBase, _NSArrayCore>, #_BridgeStorage.rawValue
+  %15 = struct_extract %14 : $_BridgeStorage<__ContiguousArrayStorageBase, AnyObject>, #_BridgeStorage.rawValue
   strong_release %15 : $Builtin.BridgeObject
   %18 = tuple ()
   return %18 : $()
@@ -190,7 +190,7 @@ bb0(%0 : $TrivialDestructor):
   %12 = tuple_extract %4 : $(Array<TrivialDestructor>, Builtin.RawPointer), 0
   %13 = struct_extract %12 : $Array<TrivialDestructor>, #Array._buffer
   %14 = struct_extract %13 : $_ArrayBuffer<TrivialDestructor>, #_ArrayBuffer._storage
-  %15 = struct_extract %14 : $_BridgeStorage<__ContiguousArrayStorageBase, _NSArrayCore>, #_BridgeStorage.rawValue
+  %15 = struct_extract %14 : $_BridgeStorage<__ContiguousArrayStorageBase, AnyObject>, #_BridgeStorage.rawValue
   strong_release %15 : $Builtin.BridgeObject
 
   return %22 : $TrivialDestructor
@@ -217,7 +217,7 @@ bb0(%0 : $TrivialDestructor, %1 : $TrivialDestructor):
   %7 = pointer_to_address %6 : $Builtin.RawPointer to [strict] $*TrivialDestructor
   %13 = struct_extract %5 : $Array<TrivialDestructor>, #Array._buffer
   %14 = struct_extract %13 : $_ArrayBuffer<TrivialDestructor>, #_ArrayBuffer._storage
-  %15 = struct_extract %14 : $_BridgeStorage<__ContiguousArrayStorageBase, _NSArrayCore>, #_BridgeStorage.rawValue
+  %15 = struct_extract %14 : $_BridgeStorage<__ContiguousArrayStorageBase, AnyObject>, #_BridgeStorage.rawValue
   cond_br undef, bb1, bb2
 
 bb1:
@@ -260,7 +260,7 @@ bb1:
   %7 = pointer_to_address %6 : $Builtin.RawPointer to [strict] $*TrivialDestructor
   %13 = struct_extract %5 : $Array<TrivialDestructor>, #Array._buffer
   %14 = struct_extract %13 : $_ArrayBuffer<TrivialDestructor>, #_ArrayBuffer._storage
-  %15 = struct_extract %14 : $_BridgeStorage<__ContiguousArrayStorageBase, _NSArrayCore>, #_BridgeStorage.rawValue
+  %15 = struct_extract %14 : $_BridgeStorage<__ContiguousArrayStorageBase, AnyObject>, #_BridgeStorage.rawValue
   strong_retain %0 : $TrivialDestructor
   store %0 to %7 : $*TrivialDestructor
   strong_release %15 : $Builtin.BridgeObject

test/SILOptimizer/licm_multiend.sil

@@ -55,7 +55,7 @@ bb0:
   %1 = struct_element_addr %0 : $*ReversedCollection<Array<Int>>, #ReversedCollection._base
   %2 = struct_element_addr %1 : $*Array<Int>, #Array._buffer
   %3 = struct_element_addr %2 : $*_ArrayBuffer<Int>, #_ArrayBuffer._storage
-  %4 = struct_element_addr %3 : $*_BridgeStorage<__ContiguousArrayStorageBase, _NSArrayCore>, #_BridgeStorage.rawValue
+  %4 = struct_element_addr %3 : $*_BridgeStorage<__ContiguousArrayStorageBase, AnyObject>, #_BridgeStorage.rawValue
   %5 = load %4 : $*Builtin.BridgeObject
   %6 = unchecked_ref_cast %5 : $Builtin.BridgeObject to $__ContiguousArrayStorageBase
   %7 = ref_element_addr %6 : $__ContiguousArrayStorageBase, #__ContiguousArrayStorageBase.countAndCapacity
@@ -140,7 +140,7 @@ bb0:
   %1 = struct_element_addr %0 : $*ReversedCollection<Array<Int>>, #ReversedCollection._base
   %2 = struct_element_addr %1 : $*Array<Int>, #Array._buffer
   %3 = struct_element_addr %2 : $*_ArrayBuffer<Int>, #_ArrayBuffer._storage
-  %4 = struct_element_addr %3 : $*_BridgeStorage<__ContiguousArrayStorageBase, _NSArrayCore>, #_BridgeStorage.rawValue
+  %4 = struct_element_addr %3 : $*_BridgeStorage<__ContiguousArrayStorageBase, AnyObject>, #_BridgeStorage.rawValue
   %5 = load %4 : $*Builtin.BridgeObject
   %6 = unchecked_ref_cast %5 : $Builtin.BridgeObject to $__ContiguousArrayStorageBase
   %7 = ref_element_addr %6 : $__ContiguousArrayStorageBase, #__ContiguousArrayStorageBase.countAndCapacity

test/api-digester/Outputs/stability-stdlib-abi.swift.expected

@@ -305,3 +305,25 @@ Var Set._Variant.object has declared type change from _BridgeStorage<_RawSetStor
 Var _CocoaSet.object has declared type change from _NSSet to AnyObject
 
 Protocol _NSNumber has been removed
+
+Class _ContiguousArrayStorage has removed conformance to _NSArrayCore
+Class __ContiguousArrayStorageBase has removed conformance to _NSArrayCore
+Class __EmptyArrayStorage has removed conformance to _NSArrayCore
+Class __SwiftDeferredNSArray has removed conformance to _NSArrayCore
+Class __SwiftNativeNSArrayWithContiguousStorage has removed conformance to _NSArrayCore
+Constructor Array.init(_immutableCocoaArray:) has parameter 0 type change from _NSArrayCore to AnyObject
+Constructor _ArrayBuffer.init(nsArray:) has parameter 0 type change from _NSArrayCore to AnyObject
+Constructor _ArrayBuffer.init(storage:) has parameter 0 type change from _BridgeStorage<__ContiguousArrayStorageBase, _NSArrayCore> to _BridgeStorage<__ContiguousArrayStorageBase, AnyObject>
+Constructor _CocoaArrayWrapper.init(_:) has parameter 0 type change from _NSArrayCore to AnyObject
+Func _ArrayBuffer._asCocoaArray() has return type change from _NSArrayCore to AnyObject
+Func _CocoaArrayWrapper.contiguousStorage(_:) has been removed
+Func _ContiguousArrayBuffer._asCocoaArray() has return type change from _NSArrayCore to AnyObject
+Func _bridgeCocoaArray(_:) has parameter 0 type change from _NSArrayCore to AnyObject
+Protocol _NSArrayCore has been removed
+Struct _CocoaArrayWrapper has type witness type for BidirectionalCollection.SubSequence changing from Slice<_CocoaArrayWrapper> to _SliceBuffer<AnyObject>
+Struct _CocoaArrayWrapper has type witness type for Collection.SubSequence changing from Slice<_CocoaArrayWrapper> to _SliceBuffer<AnyObject>
+Struct _CocoaArrayWrapper has type witness type for RandomAccessCollection.SubSequence changing from Slice<_CocoaArrayWrapper> to _SliceBuffer<AnyObject>
+Struct _CocoaArrayWrapper has type witness type for Sequence.SubSequence changing from Slice<_CocoaArrayWrapper> to _SliceBuffer<AnyObject>
+Var _ArrayBuffer._nonNative has declared type change from _NSArrayCore to _CocoaArrayWrapper
+Var _ArrayBuffer._storage has declared type change from _BridgeStorage<__ContiguousArrayStorageBase, _NSArrayCore> to _BridgeStorage<__ContiguousArrayStorageBase, AnyObject>
+Var _CocoaArrayWrapper.buffer has declared type change from _NSArrayCore to AnyObject